Actron CP9015 Ford Code Scanner

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Car Computer Code ReaderDomestic Ford, Lincoln,Mercury with EEC-IV orMCU Engine ComputerControl Systems

Lector de Códigosde Computadorasde AutomóvilFord, Lincoln, Mercurynacionales de EE.UU. conSystemas MCU y EEC-IV (para EUA)

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CP9015

Instrucciónes en español - página 67

Lecteur de coded'ordinateurautomobileFord, Lincoln, Mercurydomestiques Étas-Unisavec Systèmes MCU ou EEC-IV

Instructions en français - page 133

FAVOR DE LEER INSTRUCTCTIVO ANTES DE USAR EL ARTICULO

Para Nombre, Domicilio y Telefono del Importador: Ver Empaque

Tensión: 16VHecho en: China

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Congratulations on purchasing yourActron Code Scanner for accessingengine trouble-codes required forrepairing vehicles equipped withcomputers. Your Actron Code Scanner ismade by Actron, the largest and mosttrusted name in automotive diagnosticequipment for the home mechanic. Youcan have confidence this productmaintains the highest quality inmanufacturing, and will provide youyears of reliable service.

This instruction manual is divided intoseveral key sections. You will finddetailed steps on using the CodeScanner and important information abouttrouble code meanings, how a computercontrols engine operation, and more!

Identifying the problem is the first step insolving that problem. Your Actron CodeScanner can help you determine byaccessing the engine computer troublecodes. Armed with that knowledge, youcan either refer to an appropriate servicemanual or discuss your problem with aknowledgeable service technician. Ineither event you can save yourself a lotof valuable time and money in autorepair. And feel confident that yourvehicle’s problem has been fixed!

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1 About Codes: Where do theycome from and what are they for? .. 3

2 Code Scanner Basics: When doyou use it and what does it do? ....... 5

3 Connector Location: Connectortype identifies the computer systemin your vehicle: EEC-IV or MCU. ..... 7

4 Using the Code Scanner – EEC-IVsystem: Complete description forreading and using service codes .... 8

5 Code Meanings – EEC-IV system:Service Code Definitions for FordEEC-IV engines ............................ 20

6 Other Features – EEC-IV system:Additional Code Scanner DiagnosticTests .............................................. 31

7 Using the Code Scanner – MCUsystem: Includes engine off andengine running tests. ..................... 37

8 Code Meanings – MCU system:Service Code Definitions for FordMCU engines ................................ 47

9 Computer Basics: What does theengine computer do?Learn more about how your enginecomputer operates and controlsvehicle functions. ........................... 49

10 Reference Glossary: Includescomponent descriptions and termdefinitions commonly used inreference to engine computersystems ......................................... 55

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• Always wear approved eye protection.

• Always operate the vehicle in a well ventilated area.Do not inhale exhaust gases – they are very poisonous!

• Always keep yourself, tools and test equipment away from allmoving or hot engine parts.

• Always make sure the vehicle is in park (Automatic transmis-sion) or neutral (manual transmission) and that the parkingbrake is firmly set. Block the drive wheels.

• Never leave vehicle unattended while running tests.

• Never lay tools on vehicle battery. You may short the terminalstogether causing harm to yourself, the tools or the battery.

• Never smoke or have open flames near vehicle.Vapors from gasoline and charging battery are highly flam-mable and explosive.

• Always keep a fire extinguisher suitable for gasoline/electrical/chemical fires handy.

• Always turn ignition key OFF when connecting or disconnect-ing electrical components, unless otherwise instructed.

• Always follow vehicle manufacturer’s warnings, cautions andservice procedures.

��Some vehicles are equipped with safety air bags.

You must follow vehicle service manual cautions when workingaround the air bag components or wiring. If the cautions are notfollowed, the air bag may open up unexpectedly, resulting inpersonal injury. Note that the air bag can still open up severalminutes after the ignition key is off (or even if the vehicle batteryis disconnected) because of a special energy reserve module.

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�� The computer system in today’s vehiclesdoes more than control engine operation– it can help you find problems, too!Special testing abilities are permanentlyprogrammed into the computer by factoryengineers. These tests check thecomponents connected to the computerwhich are used for (typically): fueldelivery, idle speed control, spark timingand emission systems. Mechanics haveused these tests for years. Now you cando the same thing by using the ActronCode Scanner tool!

�� The engine computer runs the specialtests. The type of testing varies withmanufacturer, engine, model year etc.There is no “universal” test that is thesame for all vehicles. The tests examineINPUTS (electrical signals going IN tothe computer) and OUTPUTS (electricalsignals coming OUT of the computer.)Input signals which have “wrong” valuesor output circuits which don’t behavecorrectly are noted by the test programand the results are stored in thecomputer’s memory. These tests areimportant. The computer can not controlthe engine properly if it has bad inputs oroutputs!

�� The test results are stored by using codenumbers, usually called “trouble codes”or “service codes.” For example, a code63 might mean “throttle position sensorsignal voltage is too low.” Code meaningsare listed in Sections 5 and 8. Specificcode definitions vary with manufacturer,engine and model year, so you may wantto refer to a vehicle service manual foradditional information. These manualsare available from the manufacturer,

other publishers or your local publiclibrary. (See manual listing on page 4.)

�� You obtain trouble codes from theengine computer memory by using theActron Code Scanner tool. Refer tosection 4 or 7 for details. After you getthe trouble codes, you can either:

• Have your vehicle professionallyserviced. Trouble codes indicateproblems found by the computer.

or,

• Repair the vehicle yourself usingtrouble codes to help pinpoint theproblem.

� �� To find the problem cause yourself, youneed perform special test procedurescalled “diagnostics”. These proceduresare in the vehicle service manual. Thereare many possible causes for anyproblem. For example, suppose youturned on a wall switch in your homeand the ceiling light did not turn on. Is ita bad bulb or light socket? Is the bulbinstalled correctly? Are there problemswith the wiring or wall switch? Maybethere is no power coming into thehouse! As you can see, there are manypossible causes. The diagnostics writtenfor servicing a particular trouble codetake into account all the possibilities. Ifyou follow these procedures, you shouldbe able to find the problem causing thecode and fix it if you want to “do-it-yourself.”

�� !�� Using the Actron Code Scanner toobtain trouble codes is fast and easy.

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Trouble codes give you valuableknowledge – whether you go forprofessional vehicle servicing or “do-it-yourself. ” Now that you know what

trouble codes are and where they comefrom, you are well on your way to fixingtoday’s computer controlled vehicles!

(��)��The following is a list of publishers who have manuals containing trouble code repairprocedures and related information. Some manuals may be available at auto partsstores or your local public library. For others, you need to write for availability andprices, specifying the make, style and model year of your vehicle.

Vehicle Service Manuals:

Chilton Book Co.Chilton WayRadnor, PA 19089

Haynes Publications861 Lawrence DriveNewbury Park, CA 91320

Cordura PublicationsMitchell Manuals, Inc.P. O. Box 26260San Diego, CA 92126

“Electronic Engine Controls”

“Fuel Injection and Feedback Carbure-tors”

“Fuel Injection and Electronic EngineControls”

“Emissions Control Manual”

...or similar titles

Vehicle Service Manuals from FordMotor Company: (Ford, Lincoln,Mercury)

Ford Publication DepartmentHelm IncorporatedP. O. Box 07150Detroit, MI 48207

1985 & Newer: “Emission DiagnosisEngine/Electronics”

1981-1984: “Engine/EmissionsDiagnosis”

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CP9015 – Ford, Lincoln & MercuryDomestic 1981& Newer

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"��#�� Use the Code Scanner:

• When you experience a driveabilityproblem with your vehicle.

• When the “Check Engine” light comeson (if used on vehicle).

• For a routine system check – even onvehicles with a “Check Engine” light.

"�� The Code Scanner makes the vehiclecomputer run special tests to check outvarious parts of the system. The CodeScanner plugs into vehicle wiring whichconnects directly into two enginecomputer circuits. One circuit is calledSelf-Test Input (STI). The Code Scanneruses this wire to tell the computer to runthe tests. The other circuit is called Self-Test Output (STO).

The computer sends test results back tothe Code Scanner by using a pulse typesignal on this wire.

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��$��%&'�(��This switch connects to the computer’sSelf-Test Input (STI) circuit.

• HOLD – The STI wire is unconnected.(Normal position – no testing.)

• TEST – The STI wire is connected tovehicle ground. (Computer startstesting procedure.)

��)��'*!��&#�+#��This light is connected to the STO circuitcoming from the computer.

• Light OFF – The STO signal is “high”(about 5 volts present).

• Light ON – The STO signal is “low”(near zero volts).

A pulse type signal on the STO wire willcause this light to blink. This is how thecomputer sends test results to the CodeScanner. See Section 4 or 7 for details.

Note: With the Code Scanner con-nected and ignition key OFF, the lightmay be ON or OFF – depends uponvehicle. This does not affect testingperformance.

�,��#�-&��• Switch ON – A tone sounds whenever

the Self-Test Output light is lit.

• Switch OFF – Tone is always OFF.

This feature is useful when the STO lightcan not be easily seen, such as whenperforming the “wiggle” test described inSection 6.

Note: With the Code Scanner con-nected, Audio switch ON and ignition keyOFF, the tone may be ON or OFF (nomatter what the light does) – dependsupon vehicle. This does not affect testingperformance.

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�� +�� A 9 volt transistor radio battery (NEDA1604) is required to power the CodeScanner. Either a regular or alkalinebattery may be used. The CodeScanner has an automatic battery shut-off when not in use. There is no “poweroff” switch because the unit uses nopower when the light is off and the toneis quiet. The battery must be installedbefore use.

)�� -��Do the following:

1) Remove two screws from the bottomside of the Code Scanner.

2) Separate the two halves of the CodeScanner.

3) Insert battery:

4) Reassemble Code Scanner caseand replace screws.

��%��-��Do the following:

1) Put the Hold/Test switch in TESTposition.

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2) Put the Audio switch in ON position.

3) Use a coin to touch the two side-by-side terminals on the bottom row (theone with three terminals) of the CodeScanner connector.

4) Both the STO light and the toneshould turn ON. Replace batterywhen the light or tone gets weak.

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�� The Code Scanner plugs into thevehicle “Self-Test” connector which islocated in the engine compartment.

• The EEC-IV computer system (most1984 & up vehicles) uses TWO testconnectors.

– A large six sided connector.

– A small single wire “pigtail”connector.

Both of these connectors must beplugged into the Code Scannerbefore use.

• The MCU system (most 1981 – 1983vehicles) uses ONE test connector.

– A large six sided connector,identical to the one used with EEC-IVsystems. This connector must beplugged into the Code Scannerbefore use. The MCU system doesNOT use the small “pigtail” connector.

�� You can tell which computer system is inyour vehicle by noting which connectortype is installed!

The connectors are located in one of sixgeneral areas.

• Near the fire wall (right or left side ofvehicle)

• Near the wheel well (right or left sideof vehicle)

• Near the front corner of the enginecompartment (right or left side ofvehicle)

The connectors are easy to miss – takeyour time looking! They are usually gray,or other dark color, and located close toa wiring harness. They may be cappedwith a plastic cover or shroud labeled“EEC TEST” or similar wording.

&�� Vehicles made after 1988 may haveadditional computer controlled systemsinstalled, such as Anti-Lock Brakes(ABS), active suspension and the like.These systems use a test connectoridentical to EEC-IV six sided one. Thesesystems do NOT use the extra “pigtail”connector! The Code Scanner iscompatible with most of these systems –refer to vehicle service manual forsystem description and test methods.

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Complete Description for Reading and Using Service Codes.

��*� ��This section shows you how to use theCode Scanner for:

• Running tests of the engine computersystem. (Engine off, ignition timingand engine running tests.)

• Reading service codes to pinpointproblem causes.

Before using this section:

– Read Sections 1 and 2 to learnabout service codes and the CodeScanner tool.

– Read Section 3 to find the locationof the Self-Test connector in yourvehicle. The connector type will tellyou whether you have an EEC-IVsystem or an MCU system.

– Read this section (4) if you have anEEC-IV system. Use Section 7 if youhave an MCU system.

��!�� The Self-Test procedure (also called“Quick Test”) involves engine off andengine running tests. The entireprocedure is summarized in the chart.Each part is fully explained on thefollowing pages.

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Part 1: Test Preparation.• Safety First! Follow all safety rules.

• Perform Visual Inspection. This oftenreveals the problem.

• Prepare Vehicle. Engine must bethoroughly warmed-up.

Part 2: To Key On Engine Off (KOEO)Self-Test.

• Get service codes to help pinpointproblems.

Part 3: Check Engine Timing.• Verify correct “base” timing (no

computercontrol) before doing next part.

Part 4: Do Key On Engine Running(KOER) Self-Test.• Get more service codes to pinpoint

problems found during engineoperating conditions.

Part 5: Evaluate/Erase “ContinuousMemory” Codes• Helps locate intermittent problems.• Removes service codes stored in

computer memory.

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1) Safety First!

• Set the parking brake.

• Put shift lever in PARK (automatictransmission) or NEUTRAL (manualtransmission).

• Block the drive wheels.

• Make sureignition keyis in OFFposition.

2) PerformVisual Inspection.

Doing a thorough visual and “hands-on” underhood inspection beforestarting any diagnostic procedure isessential!! You can find the cause ofmany drivability problems by justlooking, thereby saving yourself a lotof time.

• Has the vehicle been servicedrecently?Sometimes things get reconnectedin the wrong place, or not at all.

• Don’t take shortcuts. Inspect hosesand wiring which may be difficult tosee because of location beneath aircleaner housings, alternators andsimilar components.

• Inspect the air cleaner and ductworkfor defects.

• Check sensors and actuators fordamage.

• Inspect all vacuum hoses for:

– Correct routing. Refer to vehicleservice manual, or Vehicle EmissionControl Information (VECI) decallocated in the engine compartment.

– Pinches and kinks.

– Splits, cuts or breaks.

• Inspect wiring for:

– Contact with sharp edges. (Thishappens often.)

– Contact withhot surfaces,such asexhaustmanifolds.

– Pinched,burned orchafedinsulation.

– Proper routing and connections.

• Check Electrical Connectors for:

– Corrosion on pins.

– Bent or damaged pins.

– Contacts not properly seated inhousing.

– Bad wire crimps to terminals.

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Problems with connectors are commonin the engine control system. Inspectcarefully. Note that some connectors usea special grease on the contacts toprevent corrosion. Do not wipe off!Obtain extra grease, if needed, fromyour vehicle dealer. It is a special typefor this purpose.

3) Prepare Vehicle.

• Turn off all electrical equipment andaccessories in vehicle.

• Keep all vehicle doors closed duringtesting.

• Make sure radiator coolant andtransmission fluid are at properlevels.

• Start the engine and let it idle untilthe upper radiator hose is hot andpressurized and RPM has settled towarm engine idle speed.Check for leaks around hoseconnections.

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• Turn ignition key to OFF position.

WARNING: Always operate vehiclein a well ventilated area.Do NOT inhale exhaust gases – theyare very poisonous!

4) Check Code Scanner Battery.

• Refer to Section 2.

5) Plug the Code Scanner into theVehicle Self-Test Connectors.

• Refer to Section 3, “ConnectorLocation”.

• Connect the Code Scanner toBOTH test connectors: the small,single wire connector and the larger6-sided one.

Note: One Code Scanner pin plugsinto an unused position on large testconnector. This is normal. Also, largetest connector may have othercontacts not used by Code Scanner.

• The Code Scanner will not harm thevehicle engine computer.

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6) Have a Penciland PaperReady.

• This is forwriting downall the codes.

7) Go to SELF-TEST PART 2: Key OnEngine Off (KOEO) Self-Test.

• Do Self-Test Part 2 even if enginewill not start, stalls or runs rough.The service codes you get maypinpoint the problem. If not, refer tovehicle service manual fortroubleshooting charts related tothe vehicle symptom.

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IMPORTANT: You must complete all steps in Self-Test Part 1 beforeproceeding to Part 2.

Verify good battery in Code Scanner(Section 2).

1) VerifyIgnitionKey is inOFFPosition.

2) Put CodeScannerHOLD/TESTSwitch inHOLDPosition.

• Do the following also:

– For 4.9L only, depress clutch untilStep 5 (codes sent).

– For 7.3L diesel only, completelydepress throttle until Step 5 (codessent).

– For 2.3L turbo with octane switch,put switch in premium position.

3) Turn Ignition Key to ON Positionbut DO NOT START THE ENGINE.

4) Put Code Scanner HOLD/TESTSwitch in TEST Position.

• This starts the KOEO Self-Test.

• Testing takes anywhere from 10seconds to one minute before codesare sent.

• You may hear clicking sounds in theengine compartment as relays arebeing tested.

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5) Get Codes from the Flashing STOLight.

NOTE: If the light does not flash, goback and repeat SELF-TEST PART 2starting with Step 1. If the light stilldoes not flash, you have a problemwhich must be repaired beforeproceeding. Refer to the vehicleservice manual “No Codes” trouble-shooting chart.

• Pay no attention to the brief, rapidblinks which occur before the regularcodes are sent.

• Count flashes to get service codes.

Code 12 looks like:

❊ PAUSE ❊❊FLASH (pause) FLASH FLASH

(FLASH = 1, FLASH FLASH = 2.

Put 1 and 2 together = code 12.)

Code 23 looks like:

❊❊ PAUSE ❊❊❊FLASH FLASH (pause)FLASH FLASH FLASH

NOTE: Certain 1991 and newer vehiclesuse 3 digit codes (refer to vehicle servicemanual to determine whether yoursystem uses 2 or 3 digit codes).

These codes are sent as follows:

Code 123 looks like:

❊ PAUSE ❊❊ PAUSE ❊❊❊FLASH (pause) FLASH FLASH (pause)

FLASH FLASH FLASH

• Two groups of codes are sent at thistime. Each group is separated by a

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single flash (called a “separatorcode”)

• The first code group has KOEO(Key On Engine Off) codes – forproblems which are present now.Some service manuals call these“hard” or “on demand” codes.

– The KOEO group will alwayscontain at least one code. This willbe a “system pass” code (11 or 111)if no problems were seen.

– The KOEO code group is senttwice (so you can double check yourcode list).

• The second code group hasContinuous Memory codes – forproblems which occurred in the pastand have been “memorized” by thecomputer. These problems(sometimes called “intermittences”)may or may not be present now.

– The Continuous Memory groupwill always contain at least onecode. This will be a “system pass”code (11 or 111) if no problemswere seen.

– The Continuous Memory codegroup is sent twice (so you candouble check your code list).

• Code sequence example withKOEO codes = 21 and 32,Continuous Memory code =14:

❊❊ PAUSE ❊FLASH FLASH (pause) FLASH

(longer pause).

❊❊❊ PAUSE ❊❊FLASH FLASH FLASH (pause)

FLASH FLASH

(longer pause).


(longer pause).


FLASH FLASH

(very long pause)

❊ SEPARATOR CODE

FLASH (“separator code”)

(very long pause)

❊ PAUSE ❊❊❊❊FLASH (pause)

FLASH FLASH FLASH FLASH

(longer pause).

❊ PAUSE ❊❊❊❊FLASH (pause)

FLASH FLASH FLASH FLASH

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• Write down codes in the order they are sent.

6) Turn Ignition Key to OFF Position.

At this point you can either:

• Have your vehicle professionally serviced. Codes indicate problems found by thecomputer.or,

• Repair the vehicle yourself using service codes to help pinpoint the problem.Refer to Test Results Chart.

4�� 04��1��5��CONTINUOUS

KOEO SEPARATOR MEMORYCODES CODES CODES ACTION TO TAKE:

11 1 11 System pass. No problem found by computer during(or 111) (or 111) KOEO Self-Test. No codes stored in computer

memory. Go to SELF-TEST PART 3: Check EngineTiming. Note: If engine will not start, stalls or runsrough, refer to vehicle service manual fortroubleshooting charts related to the symptom.

Any 1 11 KOEO codes indicate system problems are presentCode(s) (or 111) now. Write down all codes. Make repairs based on

KOEO codes starting with the first code received.Refer to vehicle service manual for code trouble-shooting charts and repair procedures. RepeatKOEO Self-Test after every repair. (Sometimes arepair procedure will eliminate more than one code.)Do not proceed to SELF-TEST PART 3 until aKOEO pass code (11 or 111) is received.

Any 1 Any KOEO and Continuous Memory codes indicateCode(s) Code(s) system problems. Write down ALL codes. DO NOT

repair Continuous Memory codes at this time! (Butkeep them written down for later use in Self-TestStep 5.) First make repairs based on KOEO codesstarting with the first code received. Refer to vehicleservice manual for code troubleshooting charts andrepair procedures. Repeat KOEO Self-Test afterevery repair. (Sometimes a repair procedure willeliminate more than one code.) Do not proceed toSELF-TEST PART 3 until a KOEO pass code (11 or111) is received.

11 1 Any Code(s) Continuous Memory codes indicate system faults.(or 111) not in Write down ALL codes but DO NOT repair these

Exceptions List codes at this time! Keep them written down for lateruse in Self-Test Step 5. Continue the Self-Testprocedure: go to SELF-TEST PART 3.EXCEPTIONS: Some Continuous Memory codesmust be repaired before going to Part 3. These arelisted below. Refer to vehicle service manual forcode troubleshooting charts and repair procedures.Repeat KOEO Self-Test after every repair. Do notproceed to SELF-TEST PART 3 until all codeexceptions are eliminated.

CONTINUOUS MEMORY 15 1989 & olderCODE EXCEPTIONS 56, 66 1988-1989 5.0L SFI Mustang only

(REPAIR NOW) 45, 46, 48, 215, 216, 217, 232 and 238 vehicles withDIS (Distributorless Ignition System) only.

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This portion ofthe Self-Test procedure is where youcheck both the “base” engine timing (nocomputer adjustment ) and the ability ofthe computer to control spark advance.The correct value for base engine timingis printed on the Vehicle EmissionControl Information (VECI) decal, locatedin the engine compartment. (Base timingis 10° BTDC if not specified on the VECIdecal.) A timing light is required for thistest. Connect it to vehicle according tomanufacturers directions. (For 2.3L dualplug engines, use exhaust side plug.Refer to ignition system section in vehicleservice manual for specific instructions.)

*� �$66$�7�&�� 8��0(See page 15 for 1992 & newervehicles.)

1) Turn Ignition Key OFF.• Wait 10 seconds before proceeding.

2) Put Code Scanner HOLD/TESTSwitch in HOLD Position.

WARNING: The next step involvesstarting the engine. Observe safetyprecautions.

• Always operate vehicle in a wellventilated area. Do NOT inhaleexhaust gases – they are verypoisonous!

• Set the parking brake.• Put shift lever in PARK (automatic

transmission) or NEUTRAL (manualtransmission).

• Block the drive wheels.• Stay away from moving engine parts.

3) Start the Engine.• If engine will not start, stalls or runs

rough, refer to vehicle service

manual for troubleshooting chartsrelated to the symptom.

4) Put CodeScannerHOLD/TESTSwitch inTESTPosition.• The computer is now performing an

Engine Running Self-Test, but do notbe concerned with the test or theresulting codes at this time. It takesseveral seconds before codes aresent.

5) Wait For End of All Service CodeSignals.• STO light on Code Scanner stops

blinking.

6) Check Ignition Timing.• After the last code is sent, the

timing will remain fixed for 2minutes (unless Self-Test isdeactivated by moving Test/Holdswitch to HOLD position).

• Ignition timing (only during this 2minute period) should be 20degrees more than the base timingvalue (give or take 3 degrees).EXAMPLE: If base timing isspecified at 10°, the measuredvalue in this step should be10°+20°=30°±3°. That is, the timingshould be in the range of 27° to 33°BTDC.

• If measured timing does not meetthis specification, refer to vehicleservice manual for procedures tocheck base timing and computertiming advance circuits.

• If measured timing is OK, proceedto SELF-TEST PART 4: Key OnEngine Running (KOER) Self-Test.


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*� �$66)�7�/�� 8��0(See page 14 for 1991 & older vehicles.)

1) Turn Ignition Key OFF.

• Wait 10 seconds before proceeding.

2) Turn off Electrical Loads.

• This includes radio, headlights,blower fans, air conditioner, and thelike.

3) Disconnect the In-Line SPOUT orSAW Connector. (Depends uponignition system: SPOUT= SparkOutput; SAW = Spark AdvanceWord.)

• This disconnects the computeradvance timing signal from theignition system.

• The ignition system will now operateat “base engine” timing.

• The connector is located close to theignition module.

• There are 3 different stylesillustrated, depending upon yourvehicle type.






• Stay away from moving engineparts.

4) Start theEngine.

• Only use theignition key tostart engine –do not use aremote starter.

• If engine will not start, stalls or runsrough, refer to vehicle servicemanual for troubleshooting chartsrelated to the symptom.

5) Check Engine Timing.

• Base timing should be the same asthe VECI decal specification, give ortake 2°. Example: Specified timing is10° BTDC. Measured timing shouldbe in the range of 8° to 12°BTDC.

— Distributor System: If base timingnot correct, adjust or repair asnecessary before proceeding. Refer to ignition system section invehicle service manual forinstructions.

— Distributorless System: Basetiming is NOT adjustable. If timingnot correct, refer to ignition systemsection in vehicle service manual forpossible causes. Repair asnecessary before proceeding.

6) Reconnect the In-Line SPOUT orSAW Connector.

7) Check for Timing Advance (or RPMIncrease).

• Timing change (or RPM increase)should occur as soon as connectoris reconnected.

• If O.K. proceed to SELF-TESTPART 4.

• If not O.K. proceed to SELF-TESTPART 4, but repair Engine Runcodes 213 or 218 immediately, ifreceived.


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��.��72�4��5��04��51��.��IMPORTANT: You must complete all steps in Self-Test Parts 1,2 and 3 beforeproceeding to Part 4.

Verify good battery in Code Scanner (Section 2).

1) Verify Ignition Key is in OFFPosition.








3) Start the Engine.

• If engine will not start, stalls or runsrough, refer to vehicle servicemanual for troubleshooting chartsrelated to the symptom.

4) Run the Engine to Warm the EGOSensor.

• The EGO (Exhaust Gas Oxygen)sensor must be warmed-up tooperate for this test.

• Run engine at 2000 RPM for atleast 2 minutes.

5) Turn Engine OFF – Wait 10Seconds – Restart Engine.


• This starts the KOER (Key OnEngine Running) Self-Test.

7) Get Engine Identification (ID) Codefrom the Flashing STO Light.

NOTE: If the light does not flash, goback and repeat SELF-TEST PART 4starting with Step 5. If the light stilldoes not flash, you have a problemwhich must be repaired beforeproceeding. Refer to the vehicleservice manual “No Codes” trouble-shooting chart.

• An engine ID code is sent after afew seconds to signal the beginningof KOER Self-Test.

• Count flashes on the STO light.

– 4 cylinder: 2 Flashes.



– 7.3L Diesel: 5 Flashes.

IMPORTANT: Some actions may berequired at this time.

• Vehicles with PSPS (Power SteeringPressure Switch): Turn steeringwheel one half turn and releasewithin 1 or 2 seconds AFTERseeing engine ID code. (Thecomputer checks for switch action.)

• Vehicles with BOO (Brake On/Offswitch) when used by computer:Press and release the brake pedalAFTER seeing engine ID code. (Thecomputer checks for switch action.)

• Vehicles with OCS (OverdriveCancel Switch): Toggle the switchon and off AFTER seeing engine IDcode. (The computer checks forswitch action.)

8) Perform WOT Action After“Dynamic Response” Signal.

• The Dynamic Response signal is asingle flash on the STO lightoccurring 6 to 20 seconds after theengine ID code is sent.

❊ DYNAMIC RESPONSE

19

• Perform a brief Wide-Open-Throttle(WOT) action right after the DynamicResponsesignal.(Completelypress andreleasethrottle.)

• Somevehicles donot use this signal – no throttleaction is necessary.


• The KOER (Key On EngineRunning) codes are sent 4 to 15seconds after the DynamicResponse signal. There are no othercode groups or separator signalssent.

• Pay no attention to the brief, rapidblinks which occur before the regularcodes are sent.

• Count flashes to get service codes.This is done the same way as inSelf-Test Part 2.

Code 12 looks like:


(FLASH = 1, FLASH FLASH = 2.


Code 23 looks like:


NOTE: Certain 1991 and newer vehiclesuse 3 digit codes (refer to vehicle servicemanual to determine whether yoursystem uses 2 or 3 digit codes).

These codes are sent as follows:

Code 123 looks like:

❊ PAUSE ❊❊ PAUSE ❊❊❊FLASH (pause) FLASH FLASH (pause)

FLASH FLASH FLASH

• The KOER (Key On Engine

Running) codes are sent as agroup.

— The KOER group will alwayscontain at least one code. This willbe a “system pass” code (11 or 111)if no problems are seen.

— The KOER code group is senttwice (so you can double check yourcode list).

• Code sequence example withKOER codes = 21 and 32:


(longer pause).


FLASH FLASH

(longer pause).


(longer pause).


FLASH FLASH

• Write down codes in the order theyare sent.

• Code definitions are listed inSection 5, “Code Meanings (EEC-IVsystem).”


Refer to KOER Test Results chartfollowing.

20

4��5��04��51��5��DYNAMIC ENGINE

ENGINE RESPONSE RUNNINGID CODE CODE CODE ACTION TO TAKE:

2,3,4 or 5 1 11 No problems found by computer during KOER Self-(or 111) Test, however…

•If Continuous Memory codes were obtained inSelf-Test Part 2, go to SELF-TEST PART 5:Evaluate “Continuous Memory” codes.

•If Continuous Memory codes were NOT obtainedin Self-Test Part 2, BUT other vehicle symptoms arestill present, refer to Diagnosis by SymptomTroubleshooting Charts in vehicle service manual.(The faults are probably not related to the computersystem.)

•If Continuous Memory codes were NOT obtained inSelf-Test Part 2 and NO other vehicle symptoms arepresent, the Self-Test Diagnostic Procedure iscomplete.

2,3,4 or 5 1 Any Engine Running codes indicate system problemsCodes are present now. Write down all codes. Make repairs

based on Engine Running codes starting with thefirst code received. (Exception: Take care of code213 or 218 first, if received.) Refer to vehicle servicemanual for code troubleshooting charts and repairprocedures. Repeat KOER Self-Test after everyrepair. (Sometimes a repair procedure will eliminatemore than one code.)

98 Not sent Any Codes The Key On Engine Running Self-Test CANNOT be(or 998) performed. The computer has spotted system

problems which must be repaired before runningthis test. Go to Part 2: Key On Engine Off (KOEO)Self-Test and follow all steps.

21

��.��"2��8��9��

:��;��Do this Part if “Continuous Memory”codes (other than an 11 or 111 passcode) were received during SELF-TESTPART 2: Key On Engine Off (KOEO)and, all other Parts of the Self-Testprocedure have been completed.

• Continuous Memory codes comefrom faults which occurred in the past.The problem may still be present, or itmay have gone away. Regardless, thecodes will remain in stored incomputer memory (for retrieval duringSelf-Test Part 2) until:

• The codes are erased using theprocedure detailed later in this part.

or,

• Power is removed from the computerfor more than a few minutes. (NOTE:The KAPWR circuit supplies vehiclebattery power to the computermemory when the ignition key is off.)

or,

• The problem goes away and does notreappear. After at least 40 enginewarm-up cycles (depends uponvehicle) the code will automatically beerased from computer memory if theproblem stays away during that time.

"��01) Look at the list of Continuous

Memory codes obtained during Self-Test Part 2: Key On Engine Off(KOEO).

2) Previous repairs may have eliminatedthe causes of some (or all) of thesecodes!

3) Disregard codes which are related torepairs already made. For example, ifrepairs were made to the EngineCoolant Temperature (ECT) sensorcircuit as the result of a KOEO code,then a Continuous Memory code 21(ECT signal voltage too high) wouldbe disregarded.

4) If any codes remain, refer to vehicleservice manual for ContinuousMemory code troubleshooting chartsand repair procedures.

5) Erase Continuous Memory codesafter all repairs have been made.

��

1) Verify Ignition Key is in OFFPosition.


3) Turn Ignition Key to ON Positionbut DO NOT START THE ENGINE.

4) Put Code Scanner HOLD/TESTSwitch in TEST Position.• This starts the normal KOEO Self-

Test.

WARNING: Stay away from theradiator cooling fan! It may turn onmomentarily. (On certain vehicleswith electrically operated fans.)

5) Wait for the STO Light to StartBlinking (Codes are Being Sent).


• The switch must be moved duringthe time the STO light is blinking(the time period when codes arebeing sent).

7) The “Continuous Memory” Codesare Now Erased.


9) Disconnect Code Scanner.

22

��Code Definitions for FORD Engines with EEC-IV Computer System (Electronic

Engine Control system,version IV)

�� • If more than one

definition is listed,consult your vehicleservice manual to getthe specific meaningfor your vehicle.

• Code meanings canvary with vehicle,model year, enginetype, options and typeof test being per-formed.

• Many of the codeslisted may not apply toyour vehicle.

• Follow vehicle servicemanual procedures tofind the cause of thecode. Always start withthe first codedisplayed.

�� 01) Visual inspections are

important!

2) Problems with wiringand connectors arecommon, especially forintermittent faults.

3) Mechanical problems(vacuum leaks, bindingor sticking linkages,etc.) can make a goodsensor look bad to thecomputer.

4) Incorrect informationfrom a sensor maycause the computer tocontrol the engine inthe wrong way. Faultyengine operation mighteven make thecomputer show adifferent good sensoras being bad!

�� 0Certain 1991 and newervehicles use 3 digit codesto report the results of thesystem Self-Testprocedure. Refer to yourvehicle service manual todetermine if your systemuses 2 or 3 digit codes.The listing of 3 digit codemeanings begins onpage 24.

��System pass.� System cannot raise enginespeed above normal idle.��RPM out of specificationduring normal idleoperation.or,D.C. motor does not followdashpot.�!The Electronic ControlAssembly (ECA) hasdetected an intermittent lossof Profile Ignition Pick-up(PIP) signal during recentoperation.�"Failure in Electronic ControlAssembly (ECA) –problems with Keep AliveMemory.

��RPM too low during EngineRun Self-Test (lean fueltest).or,Idle Speed Control (ISC)RPM out of Self-Testspecification.or,Electronic DistributorlessIgnition System (EDIS)fault – Ignition DiagnosticMonitor (IDM) signal notreceived.or,Exhaust Gas Oxygen(EGO) sensor – signalvoltage indicates “rich”during Engine Run Self-Test (lean air/fuelconditions).��Exhaust Gas Oxygen(EGO) sensor - signalvoltage indicates “rich”during Engine Run Self-Test (lean air/fuelconditions).or,RPM too low during EngineRun Self-Test (rich fueltest).or,Idle Speed Control (ISC)RPM below Self-Testspecification.�#Loss of TACH signal toElectronic ControlAssembly (ECA).or,Distributorless IgnitionSystem (DIS) fault –primary circuit failure in coil1,2,3 or 4.or,Electronic DistributorlessIgnition System (EDIS) fault– failure in Spark AngleWord (SAW) circuit.�$Failure in Electronic ControlAssembly (ECA) –problems with internalvoltage regulator.or,RPM too low for EGRcheck during Engine RunSelf-Test.or,Cylinder Identification (CID)sensor input failure.

23

�Engine CoolantTemperature (ECT) sensorsignal voltage: out of range(Key On Engine Off Self-Test), not at normaloperating temperature(Engine Run Self-Test) orloss of signal (duringnormal engine operation).or,Electronic DistributorlessIgnition System (EDIS) fault– problems with CrankshaftPosition Sensor (CPS)circuit. Manifold Absolute Pressure(MAP) sensor or BarometricPressure (BP) sensor –signal voltage out ofspecification (engine off) ornot at normal vacuum levels(engine running). �Throttle Position (TP)sensor – signal voltage outof Self-Test specification. !Air Charge Temperature(ACT) sensor or Vane AirTemperature (VAT) sensor –signal voltage is out ofspecification (engine off) ornot at normal levels (enginerunning).or,Electronic DistributorlessIgnition System (EDIS) fault –failure in coil 1 primarycircuit. "Knock Sensor (KS) signalnot detected during EngineRun Self-Test (DynamicResponse test). �Vane Air Flow (VAF) sensoror Mass Air Flow (MAF)sensor – signal voltage outof Self-Test specifications.or,Transmission OilTemperature (TOT) sensor– signal voltage is out ofSelf-Test specification. �Vehicle Speed Sensor(VSS) – signal voltage istoo low.or,Electronic DistributorlessIgnition System (EDIS) fault– failure in coil 2 primarycircuit. #Vane Air Temperature(VAT) sensor – signalvoltage out of Self-Testspecification.

or,Electronic DistributorlessIgnition System (EDIS) fault– failure in coil 3 primarycircuit.or,Distributorless IgnitionSystem (DIS) fault – Loss ofright side TACH signal. $Vehicle Speed Sensor (VSS)– signal voltage is too low.��EGR Valve Position (EVP)sensor or PressureFeedback EGR (PFE)sensor – signal voltage isbelow minimumspecification.or,EGR Vacuum Regulator(EVR) solenoid circuitproblems.or,EGR valve is not in itsnormal closed position.� EGR Valve Position (EVP)sensor or PressureFeedback EGR (PFE)sensor – signal voltage isbelow closed limit or hasgone beyond set limits.or,Problems with EGR valvecontrolling.��EGR Valve Position (EVP)sensor or PressureFeedback EGR (PFE)sensor indicates EGR valveis not opening.or,EGR Valve Position (EVP)sensor or PressureFeedback EGR (PFE)sensor indicates EGR valvenot seated (closed) properly.�!EGR Valve Position (EVP)sensor or PressureFeedback EGR (PFE)sensor: signal voltage out ofSelf-Test specification limits,or,signal voltage above closedlimit during normal engine runoperation,or,signal indicates insufficientEGR flow.�"EGR Valve Position (EVP)sensor or PressureFeedback EGR (PFE)sensor: signal voltage aboveSelf-Test specification limits,or,

signal voltage too highduring normal engine runoperation.or,RPM too low to performEGR test (Engine Run Self-Test).�#Idle Tracking Switch (ITS)circuit open.�$Transaxle problem: lock-upfailed in torque convertor,or,convertor bypass clutch notapplying properly.!�Exhaust Gas Oxygen(EGO) sensor: voltagesignal always “lean” (lowvalue) – does not switch.! Exhaust Gas Oxygen (EGO)sensor: voltage signalalways “rich” (high value) –does not switch.!�Exhaust Gas Oxygen(EGO) sensor: voltagesignal “lean” (low value)during wide-open -throttledriving condition,or,sensor has cooled downand may not haveresponded properly duringEngine Run Self-Test.!!Problems in Thermactor AirControl system.!"Thermactor air flow isalways upstream duringEngine Run Self-Test.or,Distributorless IgnitionSystem (DIS) or ElectronicDistributorless IgnitionSystem (EDIS) problems –primary circuit failure in coil1, 2, 3 or 4.!�Thermactor Air Systemunable to bypass air (ventto atmosphere).or,Distributorless IgnitionSystem (DIS) or ElectronicDistributorless IgnitionSystem (EDIS) problems –primary circuit failure in coil2.!�Exhaust Gas Oxygen(EGO) sensor signalvoltage indicates “rich”during “lean” air/fuelconditions.or,

24

Vane AIr Flow (VAF)sensor – voltage signal istoo low.or,Transaxle problem – 4x4Lswitch is closed.!#Vane Air Flow (VAF)sensor – voltage signal toohigh.or,Distributorless IgnitionSystem (DIS) problems:Coil 3 circuit failure,or,Loss of left sideTACH signal.or,Exhaust Gas Oxygen(EGO) sensor – signalvoltage indicates oppositefrom fuel.!$Electronic DistributorlessIgnition System (EDIS) –Spark Advance Word(SAW) signal error.or,Spark Output (SPOUT)signal changed ignitiontiming to 10° BTDC (BeforeTop Dead Center).or,Transaxle problem: 1-2shift error."�Engine CoolantTemperature (ECT) sensor– signal voltage is too high." Power Steering PressureSwitch (PSPS) – circuit isopen or no changesdetected."�Throttle Position (TP)sensor – signal voltage istoo high (as if indicatingwide-open-throttlecondition)."!Air Charge Temperature(ACT) sensor or Vane AirTemperature (VAT) sensor– signal voltage is too high.""Open connection inKeypower circuit orelectrical charging voltagetoo low."�Mass Air Flow (MAF)sensor or Vane Air Flow(VAF) sensor – voltagesignal too high.or,

Electronic 4-SpeedOverdrive AutomaticTransaxle (E4OD):Transmission OilTemperature (TOT) sensor– signal voltage is too high."�Neutral Pressure Switch(NPS) – open circuit failure,or,Circuit failed in Neutralposition.or,Octane adjust service pininstalled."#Vane Air Temperature (VAT)sensor – signal voltage toohigh (open connection incircuit).or,Crank fuel delay service pin inuse – circuit connected toground.or,Idle Tracking Switch (ITS)circuit failure – incorrect switchsignal indications during Self-Test."$Transaxle problem – failurein 4/3 pressure switchcircuit (open connection).or,Low speed fuel pump circuitfailure.or,Idle speed adjust servicepin in use – circuitconnected to ground.��Engine CoolantTemperature (ECT) sensor– signal voltage is too low.or,Indicates that the IdleTracking Switch is open (incontact with the throttlelever) with the Idle SpeedControl Motor fullyretracted.� Transaxle problem – 4/3 or3/2 pressure switch circuitfailed closed,or,convertor clutch failure.��Throttle Position (TP)sensor – signal voltage istoo low.�!Air Charge Temperature(ACT) sensor or Vane AirTemperature (VAT) sensor– signal voltage is too low.�"Electrical charging systemproblem occurred – voltagetoo high (over 17.5 volts).

or,Engine control systemnever went into closed loopfuel operation.or,Transaxle problem –Overdrive Cancel Switch(OCS) was not cycledduring Engine Run Self-Test.��Mass Air Flow (MAF)sensor or Vane Air Flow(VAF) sensor – voltagesignal too low.or,Transmission OilTemperature (TOT) sensor– signal voltage is too low.��Improper signals are beingreceived from either theNeutral Drive Switch (NDS),Neutral Gear Switch (NGS),Neutral Pressure Switch(NPS), Clutch Switch (CS),Manual Lever Position(MLP) sensor or AirConditioner Clutch (ACC).or,Air Conditioner (A/C) onduring Self-Test.�#Vane Air Temperature(VAT) sensor – signalvoltage is too low.or,Transmission TemperatureSwitch (TTS) – open circuitfailure.or,Idle Tracking Switch (ITS)circuit failure – incorrectswitch signal indicationsduring Self-Test.�$Transaxle problem – Opencircuit failures with 3/2pressure switch or 3/4pressure switch,or,3-4 switch error.�%Problem with ElectronicControl Assembly (ECA) –failure in DataCommunications Link(DCL).��Problem with ElectronicControl Assembly (ECA) –software reset detected.or,Problem with MessageCenter Control Assembly(MCCA) – failure in DataCommunications Link(DCL).

25

� Insufficient manifoldvacuum change detectedduring Dynamic Responseportion of Engine Run Self-Test.or,Problem with MessageCenter Control Assembly(MCCA) – failure in DataCommunications Link(DCL).or,Power interrupt detected.��Insufficient throttle positionchange detected duringDynamic Response portionof Engine Run Self-Test.�!Brake ON/OFF (BOO)switch action not detectedduring Dynamic Responseportionof Engine Run Self-Test.�"Brake ON/OFF (BOO)switch always closedcircuit.��Insufficient Vane Air Flow(VAF) sensor changedetected during DynamicResponse portion of EngineRun Self-Test.��Operator error duringDynamic Response portionof Engine Run Self-Test.�#Power interrupt detected.or,Flexible fuel sensor circuitfailure.�$Air Conditioner (A/C) onduring Self-Test.#�Thermactor Air Diverter(TAD or AM-2) solenoid:circuit failure.or,Electro-Drive Fan: circuitfailure.or,Intake Air Control (IAC)valve: circuit failure.or,Boost solenoid – circuitfailure.# Thermactor Air Bypass(TAB or AM-1) solenoid:circuit failure.or,Electro-Drive Fan: circuitfailure.or,

Supercharger BypassSolenoid (SBS): circuitfailure.#�High Speed Electro-DriveFan (HEDF) – circuit failure.or,EGR Control (EGR-C)solenoid–open circuit failure.or,Low speed fuel pump relay –open circuit failure.#!EGR Vacuum (EGR-V)solenoid – circuit failure.or,EGR Vacuum Regulator(EVR) solenoid–circuit failure.or,EGR Shut-Off (EGR S/O)solenoid – circuit failure.#"Cannister Purge (CANP)solenoid – circuit failure.or,Transaxle problem – 3/4 shiftsolenoid circuit failure.or,Electronic Control Assembly(ECA) status – adaptive“lean” limit reached in fuelcontrol program.#�Transaxle problem – 3/4 shiftsolenoid circuit failure.or,Electronic Control Assembly(ECA) status – adaptive“rich” limit reached in fuelcontrol program.or,Wide-open-throttle Airconditioner Clutch (WAC)solenoid – circuit failure.#�Fuel Pump (FP) relay –circuit failure.##Electro-Drive Fan (EDF)relay – circuit failure.or,Converter Clutch Override(CCO) solenoid – circuitfailure.or,Distributorless IgnitionSystem (DIS) problems –loss of dual plug control.or,Throttle Kicker (TK) solenoid– circuit failure.#$Lock-Up Solenoid (LUS) –circuit failure.or,Converter Clutch Override(CCO) solenoid – circuitfailure.or,

Exhaust Heat Control(EHC) solenoid – circuitfailure.$�Exhaust Gas Oxygen (EGO)sensor – signal voltagealways indicates “lean”either during Engine RunSelf-Test (“rich” air/fuelconditions) or normalengine operatingconditions.or,Transaxle problem – ShiftSolenoid 1 (SS1) circuitfailure.$ Right side Exhaust GasOxygen (EGO) sensor –signal voltage alwaysindicates “rich” duringEngine Run Self-Test(“lean” air/fuel conditions).or,Transaxle problem – ShiftSolenoid 2 (SS2) circuitfailure.$�Throttle Position (TP)sensor – signal voltage toolow during Self-Test (atmaximum extension of idlespeed control motor).or,Right side Exhaust GasOxygen (EGO) sensor –cool down occurred.or,Transaxle problem – CoastClutch Solenoid (CCS)circuit failure.$!Thermactor Air System –problem on the right bank(passenger side).or,Transaxle problem – ShiftSolenoid 1 (SS1) circuitfailure.$"Thermactor Air Systemproblem – right (passenger)side air flow alwaysupstream.or,Fuel Pump Monitor (FPM)signal – indicates circuitproblem.$�Thermactor Air Systemproblem – right (passenger)side air flow will not bypass.or,Fuel Pump (FP) circuitfailure.or,High speed fuel pump relaycircuit failure.

26

$�Right side Exhaust GasOxygen (EGO) sensor –signal voltage indicates“rich” during “lean” air/fuelconditions.or,Overdrive Cancel IndicatorLight (OCIL) – circuitfailure.$#A system problem is presentcausing the ElectronicControl Assembly (ECA) tooperate in FailureManagement and EffectsMode (FMEM).or,Right side Exhaust GasOxygen (EGO) sensor –signal voltage indicates“lean” during “rich” air/fuelconditions.or,Electronic Pressure Control(EPC) solenoid – circuitfailure.$$The Electronic ControlAssembly (ECA) has notlearned to control engineidle speed (ignore code 12or 13).or,Electronic Pressure Control(EPC) solenoid – circuitfailure.

�� Certain 1991 and newervehicles use 3 digit codesto report the results ofthe system Self-Testprocedure. Refer to yourvehicle service manual todetermine if your systemuses 2 or 3 digit codes.

• Code meanings canvary with vehicle, modelyear, engine type,options and type of testbeing performed.

• Many of the codeslisted may not apply toyour vehicle.

• Follow vehicle servicemanual procedures tofind the cause of thecode. Always start withthe first code displayed.

�� 01) Visual inspections are

important!



4) Incorrect informationfrom a sensor maycause the computer tocontrol the engine inthe wrong way. Faultyengine operation mighteven make thecomputer show adifferent good sensoras being bad!

��System pass.�� Air Charge Temperature(ACT) sensor – signalvoltage is too low.

��Air Charge Temperature(ACT) sensor – signalvoltage is too high.��!Air Charge Temperature(ACT) sensor – signalvoltage is higher or lowerthan expected.��Engine CoolantTemperature (ECT) sensor– signal voltage is higher orlower than expected.��Engine CoolantTemperature (ECT) sensor– signal voltage is too low.��#Engine CoolantTemperature (ECT) sensor– signal voltage is too high.� �Throttle Position (TP)sensor– signal voltage ishigher or lower thanexpected.or,Throttle Position (TP)sensor– signal voltageinconsistent with engineintake air flow.� Throttle Position (TP)sensor – signal voltage istoo low.� �Throttle Position (TP)sensor – signal voltage istoo high.� !Throttle Position (TP)sensor – signal voltage ishigher than expected.� "Throttle Position (TP)sensor – signal voltage islower than expected.� �Manifold Absolute Pressure(MAP) or BarometricPressure (BP) – signalvalues higher or lower thanexpected.� #Manifold Absolute Pressure(MAP) sensor – vacuumhose disconnected ordamaged.� $Manifold Absolute Pressure(MAP) sensor or Mass AirFlow (MAF) sensor –insufficient signal valuechange during DynamicResponse test (Engine RunSelf-Test).

27

��Heated Exhaust GasOxygen (HEGO) sensor –voltage signal not switchingduring Engine Run Self-Test. Indicates “lean” (Bank#2).��Heated Exhaust GasOxygen (HEGO) sensor –voltage signal not switchingduring Engine Run Self-Test. Indicates “rich” (Bank#2).��#Cold Start Injector (CSI) –insufficient flow duringEngine Run Self-Test.��$Exhaust Gas Oxygen(EGO) sensor – noswitching detected (Bank#2).�!�Fuel system indicates“lean” with high flowdemand.�!!Exhaust Gas Oxygen(EGO) sensor – noswitching detected (Bank#1).�"�Mass Air Flow (MAF)sensor – signal voltage istoo low�"#Mass Air Flow (MAF)sensor – signal voltage istoo high�"$Mass Air Flow (MAF)sensor – signal voltage ishigher or lower thanexpected.��"“Downstream” HeatedExhaust Gas Oxygen(HEGO) sensor – voltagesignal indicates “lean”(Bank #1).��“Downstream” HeatedExhaust Gas Oxygen(HEGO) sensor – voltagesignal indicates “rich”(Bank #1).��Throttle Position (TP)sensor – insufficient signalvoltage change duringDynamic Response test(Engine Run Self-Test).��#“Downstream” HeatedExhaust Gas Oxygen(HEGO) sensor – signalvoltage too high.

��$“Downstream” HeatedExhaust Gas Oxygen(HEGO) sensor – signalvoltage too low.��Heated Exhaust GasOxygen (HEGO) sensor –voltage signal not switching(Bank #1).�� Heated Exhaust GasOxygen (HEGO) sensor –voltage signal indicates“lean” (Bank #1).��Heated Exhaust GasOxygen (HEGO) sensor –voltage signal indicates“rich” (Bank #1).��"Heated Exhaust GasOxygen (HEGO) sensor –voltage signal not switching(Bank #2).��Heated Exhaust GasOxygen (HEGO) sensor –voltage signal indicates“lean” (Bank #2).��Heated Exhaust GasOxygen (HEGO) sensor –voltage signal indicates“rich” (Bank #2).��$Heated Exhaust GasOxygen (HEGO) sensor –voltage signal notswitching: indicates “rich”during part throttle engineoperation (Bank #1).�#�Heated Exhaust GasOxygen (HEGO) sensor –voltage signal notswitching: indicates “lean”during part throttle engineoperation (Bank #1).�# Electronic ControlAssembly (ECA) status –adaptive “rich” limit reachedin fuel control program(engine idle, Bank #1).�#�Electronic ControlAssembly (ECA) status –adaptive “lean” limitreached in fuel controlprogram (engine idle, Bank#1).�#!Mass Air Flow (MAF)sensor – signal voltage ishigher than expected.

�#"Mass Air Flow (MAF)sensor – signal voltage islower than expected.�#�Injector pulsewidth higherthan expected or Mass AirFlow (MAF) sensor signalvoltage is lower thanexpected.�#�Injector pulsewidth lowerthan expected or Mass AirFlow (MAF) sensor signalvoltage is higher thanexpected.�##Heated Exhaust GasOxygen (HEGO) sensor –voltage signal notswitching: indicates “rich”during part throttle engineoperation (Bank #2).�#$Heated Exhaust GasOxygen (HEGO) sensor –voltage signal notswitching: indicates “lean”during part throttle engineoperation (Bank #2).�$�Electronic ControlAssembly (ECA) status –adaptive “rich” limit reachedin fuel control program(engine idle, Bank #2).�$ Electronic ControlAssembly (ECA) status –adaptive “lean” limitreached in fuel controlprogram (engine idle, Bank#2).�$�Flexible Fuel Sensor –circuit failure. ��Profile Ignition Pick-Up(PIP) sensor – circuitfailure. � Loss of Ignition DiagnosticMonitor (IDM) signal –shortto ground in Spark Output(SPOUT) circuit. ��Spark Output (SPOUT)circuit – open connectionfailure. �!Cylinder Identification (CID)sensor – circuit failure. �"Ignition system (distributor-less) problem – Coil #1primary side circuit failure.

28

��Ignition system (distributor-less) problem – Coil #2primary side circuit failure. ��Ignition system (distributor-less) problem – Coil #3primary side circuit failure. �#Ignition system (distributor-less) problem – Loss of leftside Ignition DiagnosticMonitor (IDM) signal. �$Ignition system problem –Spark Output (SPOUT)signal open circuit (nospark advance timing). �Distributorless IgnitionSystem (DIS) problem –Spark timing error. Distributorless IgnitionSystem (DIS) problem –Loss of right side IgnitionDiagnostic Monitor (IDM)signal. �Distributorless IgnitionSystem (DIS) problem –Loss of Dual Plug Inhibit(DPI) control. !Distributorless IgnitionSystem (DIS) problem –Primary circuit failure inCoil #1, 2, 3 or 4. "Knock Sensor (KS) signalnot detected duringDynamic Response Test(Engine Run Self-Test). �Electronic DistributorlessIgnition System (EDIS)problem – IgnitionDiagnostic Monitor (IDM)signal not received. �Electronic DistributorlessIgnition System (EDIS)problem – CrankshaftPosition Sensor (CPS)error. � Electronic DistributorlessIgnition System (EDIS)problem – Coil #1, 2, 3 or 4circuit failure. ��Electronic DistributorlessIgnition System (EDIS)problem – Spark AdvanceWord (SAW) signal error.

�#Ignition system(distributorless) problem –Coil #4 primary side circuitfailure. �$Electronic DistributorlessIgnition System (EDIS)problem – CrankshaftPosition Sensor (CPS)signal received with engineoff. !�Ignition Diagnostic Monitor(IDM) signal problem –pulsewidth error betweenElectronic DistributorlessIgnition System (EDIS) andElectronic ControlAssembly (ECA). ! Distributorless IgnitionSystem (DIS) problem –operating in failure mode. !�Electronic DistributorlessIgnition System (EDIS)problem – Secondarycircuit failure in Coil #1, 2, 3or 4. !!Cylinder Identification (CID)circuit failure duringCylinder Balance Test.��Thermactor Air Systemproblem – no operationduring Engine Run Self-Test (Bank #1).�� Thermactor Air Systemproblem – air flowmisdirected during EngineRun Self-Test.��Thermactor Air Systemproblem – air flow notbypassed (vented toatmosphere) during EngineRun Self-Test.��!Thermactor Air Systeminoperative during EngineRun Self-Test (Bank #2with dual oxygen sensors).��"Thermactor Air Systemproblem – inadequate airflow during cold start.��Thermactor Air Systemproblem – inadequate airflow during hot engine lowRPM.

��Thermactor Air Systemproblem – air flow notbypassed (vented toatmosphere) during EngineRun Self-Test.��#Engine Air Management(EAM) System problem –monitor circuit signalvoltage is high whencommanded off.��$Engine Air Management(EAM) System problem –monitor circuit signalvoltage is low whencommanded on.� �Pressure Feedback EGR(PFE) sensor or EGRPressure Transducer (EPT)– signal voltage lower thanexpected.� �EGR Valve Position (EVP)sensor, Pressure FeedbackEGR (PFE) sensor or EGRPressure Transducer (EPT)– signal voltage too low.� #EGR Valve Position (EVP)sensor – signal voltagelower than expected(closed valve position).�� Insufficient EGR flowdetected.��!EGR Valve Position (EVP)sensor – signal voltagehigher than expected(closed valve position).��"Pressure Feedback EGR(PFE) sensor or EGRPressure Transducer (EPT)– signal voltage higher orlower than expected (KeyOn Engine Off Self-Test).��Pressure Feedback EGR(PFE) sensor or EGRPressure Transducer (EPT)– signal voltage higher thanexpected (exhaust pressurehigh).��EGR Valve Position (EVP)sensor, Pressure FeedbackEGR (PFE) sensor or EGRPressure Transducer (EPT)– signal voltage too high.��#Engine CoolantTemperature (ECT) sensor– signal voltage lower thanexpected.

29

��$Engine CoolantTemperature (ECT) sensor– signal voltage higher thanexpected.�!�Octane Adjust service pinin use.�#�Air Conditioner (A/C) clutchis cycling frequently.!��Cannot control RPM duringEngine Run Self-Test – lowRPM check.!� Cannot control RPM duringEngine Run Self-Test –high RPM check.!��Idle Speed Control actuator– operating at minimumlimit.!�!Idle Speed Control actuator– operating at maximumlimit.!�"Idle Speed Control system– minimum learning limitreached.!��Idle Speed Control system– maximum learning limitreached.!" Vehicle Speed Sensor(VSS) – signal too small.!��RPM or Vehicle SpeedSensor (VSS) limit reached.NO REPAIR REQUIRED."��Electronic ControlAssembly (ECA) problem –Read-Only Memory (ROM)test failure."� Electronic ControlAssembly (ECA) problem –Keep Alive Memory testfailure."��Electronic ControlAssembly (ECA) problem –internal voltage test failure."�$Power Steering PressureSwitch (PSPS) – openconnection circuit failure." �Power Steering PressureSwitch (PSPS) – circuitswitching not detected.

" Vehicle transmission not inPARK during Key OnEngine Off Self-Test." !Low Speed Fuel Pump –open circuit failure betweenbattery and ElectronicControl Assembly (ECA)." "Vehicle transmission ingear or air conditioner on." �Neutral Position Switch(NPS) open circuit failure orAir Conditioner on duringEngine Off Self-Test." #Clutch Switch (CS) – circuitfailure." $Data Communication Link(DCL) or Electronic EngineControl (EEC) system –circuit failure."� Cluster Control Assembly(CCA) – circuit failure."��Electronic InstrumentCluster (EIC) – circuitfailure in DataCommunication Link (DCL)."��Brake On-Off (BOO) switch– circuit failure or notactivated during EngineRun Self-Test."�#Insufficient RPM changeduring Dynamic ResponseTest (Engine Run Self-Test).or,Invalid cylinder balance test– throttle positionmovement.or,Invalid cylinder balance test– cylinder identificationproblems."�$Air conditioner or defrosteron."! Fuel Pump (FP) circuitopen connection –Electronic ControlAssembly (ECA) to motorground."!�Fuel Pump (FP) circuitopen connection –Electronic ControlAssembly (ECA) to battery.

""�Idle Air Control (IAC)solenoid – circuit failure."" Thermactor Air Bypass(TAB or AM-1) solenoid:circuit failure.""�Thermactor Air Diverter(TAD or AM-2) solenoid:circuit failure.""!Fuel Pressure RegulatorControl (FPRC) – circuitfailure."""SBS circuit failure.""�Fuel Pump (FP) relay –primary circuit failure.""�Low Speed Fuel Pump –primary circuit failure.""#EGR Valve Regulator(EVR) solenoid – circuitfailure.""$Air Conditioner Clutch(ACC) relay – circuit failure."��Turbocharger ControlSolenoid (TCS) – outputcircuit failure."� Auxiliary Electro-Drive Fan(AEDF) – circuit failure."��High Speed Electro-DriveFan (HEDF) – circuit failure."�!Electro-Drive Fan (EDF) –circuit failure."�"Cannister Purge (CANP)solenoid – circuit failure."��3/4 Shift solenoid – circuitfailure."�$Auxiliary Cannister Purge(AUX-CANP) – circuitfailure."��EGR vacuum solenoid –circuit failure."� EGR vent solenoid – circuitfailure."��Electro-Drive Fan (EDF) –operation not detectedduring Key On Engine OffSelf Test.

30

"�!High Speed Electro-DriveFan (HEDF) – operationnot detected during Key OnEngine Off Self-Test."�#Variable Control RelayModule (VCRM) – AirConditioner Pressuresensor circuit shorted."�$Variable Control RelayModule (VCRM) –insufficient Air ConditionerPressure change."#�Variable Control RelayModule (VCRM) –excessive current flow infan circuit."# Variable Control RelayModule (VCRM) – opencircuit failure in fan circuit."#�Variable Control RelayModule (VCRM) –excessive current flow infuel pump circuit."#!Variable Control RelayModule (VCRM) – opencircuit failure in modulepower ground circuit."#"Variable Control RelayModule (VCRM) –excessive current flow inAir Conditioner Clutchcircuit."#�Variable Control RelayModule (VCRM) – opencircuit failure in AirConditioner Clutch circuit."#�Variable Control RelayModule (VCRM) –communication failure.��Transmission problem: 1-2shift error.��#Transmission problem: 2-3shift error.��$Transmission problem: 3-4shift error.� �Transmission problem –Shift Solenoid 1 (SS1)circuit failure.� Transmission problem –Shift Solenoid 2 (SS2)circuit failure.

� !Electronic Pressure Control(EPC) solenoid – circuitfailure.� "Electronic Pressure Control(EPC) solenoid – circuitdriver problem in ElectronicControl Assembly (ECA).� �Coast Clutch Solenoid(CCS) – circuit failure.� �Converter Clutch Solenoid(CCC) – circuit failure.� #Excessive converter clutchslippage.� $Converter Clutch Solenoid(CCC), Converter ClutchOverride (CCO) solenoid,Lock-Up Solenoid (LUS) orMLUS – circuit failure.��Overdrive Cancel IndicatorLight (OCIL) – circuitfailure.�� Overdrive Cancel Switch(OCS) – no switch actiondetected during EngineRun Self-Test.��4x4L switch closed duringKey On Engine Off Self-Test.��!Manual Lever Position(MLP) sensor – signalvoltage higher or lower thanexpected.��"Transmission TemperatureSwitch (TTS) – open circuitfailure.��Transmission OilTemperature (TOT) sensor– signal voltage higher orlower than expected.��Transmission OilTemperature (TOT) sensor– signal voltagetoo high.��#Transmission OilTemperature (TOT) sensor– signal voltage too low.��$Turbine Speed Sensor(TSS) – insufficient signallevel.

�!�Shift Solenoid 3 (SS3) –circuit failure.�!�Shift Solenoid #4 (SS4) –circuit failure.�!"Transmission problem –incorrect gear ratioobtained for first gear.�!�Transmission problem –incorrect gear ratioobtained for second gear.�!�Transmission problem –incorrect gear ratioobtained for third gear.�!#Transmission problem –incorrect gear ratioobtained for fourth gear.�!$Electronic Pressure Control(EPC) – signal higher orlower than expected.�"�Electronic Pressure Control(EPC) solenoid – circuitfailure.�" Modulated Lock-UpSolenoid (MLUS) – circuitfailure.�"�Transmission ControlSwitch (TCS) – did notswitch during Key OnEngine Run Self-Test.�"!Manual Lever Position(MLP) sensor – notindicating PARK positionduring Key On Engine OffSelf-Test.�""Manual Lever Position(MLP) sensor – notindicating NEUTRALposition during Key OnEngine Off Self Test.�"�Converter Clutch Control –continuous slip error.�"�Excessively hottransmission oiltemperature detectedduring engine operation.�"$High vehicle speeddetected while shift leverindicating PARK position.

31

��Manual Lever Position(MLP) sensor – signalvoltage too low.��#Manual Lever Position(MLP) sensor – signalvoltage too high.��"Manual Lever Position(MLP) sensor – signalvoltage out of range.��Transmission problem –mechanical failure in firstgear and reverse.��Transmission problem –mechanical failure in firstgear and second gear.��#Transmission problem –third gear to second geardownshift error.��$Transmission problem –second gear to first geardownshift error.�$�4x4 low circuit failure.#��Fuel injector Pump Lever(FIPL) – signal voltagehigher or lower thanexpected.#� Fuel Injector Pump Lever(FIPL) – signal voltage toohigh.#��Fuel Injector Pump Lever(FIPL) – signal voltage toolow.$$#Engine control systemoperating in Failure Modeand Effects Management(FMEM) programmingstrategy.

32

33

�� !��" �� &�� ' !�� (� ��"

�� !2�5��

Service manuals call this the “OutputState Check.” You can turn on most ofthe computer controlled relays andsolenoids except the fuel pump relay andfuel injectors. This is helpful for checkingvoltages, relay operation, etc. The“output state check” is automaticallyactivated at the end of the normal KeyOn Engine Off Self-Test procedure(explained in Section 4).

��01) Safety First!




2) Make SureIgnition Keyis in OFFPosition

3) Check CodeScannerBattery

• Refer toSection 2.

4) Connect Code Scanner


• Plug BOTH test connectors into theCode Scanner!

TM

TEST

HOLD

SELF

TEST

OUTPUT

ord,

Linc

oln &

Merc

ury

1981

& New

erAU

DIO

ON

5) Put Hold/Test Switch in HOLDPosition

6) Turn IgnitionKey to ONPosition but DONOT STARTENGINE

7) Put Hold/TestSwitch in TESTPosition

• Computer isnow runningnormal KeyOn Engine Off Self-Test.

WARNING: Stay away from electricmotor driven radiator fan. It mayturn on during this procedure.

8) Wait For End of All Service CodeSignals

• STO light on Code Scanner stopsblinking.

9) “Output State Check” is NowActivated

• Fully depressand release thethrottle. At thistime most of thecomputercontrolled relaysand solenoids(except fuel pump and fuel injectors)will be energized.NOTE: The STO circuit is alsoenergized, so the STO light on theCode Scanner will turn on too!

• Repeat the action of depressing andreleasing the throttle. This will de-energize the components (STO lightwill turn off, also).

OFF

AUDIO

ON


TM

®

TEST

ST0

HOLD

SELF

TEST OUTPUT

34

• Throttle action may repeated asoften as desired to turn theactuators on and off.NOTE: If vehicle is equipped withIntegrated Vehicle Speed Control(IVSC), disconnect vacuum supplyhose from the Speed Control Servo(to release stored vacuum).Otherwise, the Speed ControlSolenoids will energize the firsttime the throttle is depressedcausing the servo to hold thethrottle wide open! Reconnect thevacuum hose after testing.

10)TurnIgnitionKey toOFFPosition

11)Disconnect Code Scanner

35

�� 32��-��

This test is only used on vehicles withSequential electronic Fuel Injection(SFI) engines. (Where the injectors arefired individually in the same sequenceas the spark plug firing sequence.) Thetest turns each injector on and off andchecks for an RPM decrease. Codesindicate cylinders which are weak or notcontributing due to problems such asdamaged injectors, spark plugs andwiring. The test must be run at the endof the normal Key On Engine RunningSelf-Test procedure (explained inSection 4) and may be repeated asoften as desired.

Warning: The following procedureinvolves starting the engine.

Always operate vehicle in a wellventilated area.

Exhaust gases are very poisonous!

1) Safety First!




2) Make Sure Ignition Key is in OFFPosition

3) Check Code Scanner Battery





5) Put Hold/Test Switch in HOLDPosition

6) Have a Pencil and Paper Ready

• This is for writing down the codes.

7) Start the Engine

• Stay away from moving parts.

8) Put Hold/Test Switch in TESTPosition

• Computer is now running normalKey On Engine Running Self-Test.

9) Wait For End of All Service CodeSignals

• STO light on Code Scanner stopsblinking.

29�� 9��2

10) Lightly Press and Release Throttleabout 10 seconds after STO Lightstops blinking

• Do NOT press throttle all the waydown!

Exception: Do brief wide-open-throttle for 1986 only.

• Test time is less than 3 minutes.

• Do not move throttle until test isover.

11) Get Codes from Flashing STOLight

• Count flashes to get codes.

NOTE: This test can give singledigit codes.

Code 3 looks like:

❊❊❊FLASH FLASH FLASH

Code 12 looks like:


(FLASH=1, FLASH FLASH=2.


• Testing is complete

36

12) Optional Retest - 1987 & Newer

• Lightly press and release throttlewithin 2 minutes after the last codeis sent. This will repeat the entirecylinder balance test.

• IMPORTANT: (Some 1987 and all1988 & newer) Repeating the test

can tell you how weak a badcylinder is. (The computer altersinspection during retest.) Testresults will be different for a good,weak or “dead” cylinder. See chartsbelow using cylinder #7 as anexample.

Example: All cylinders equal

$�� )�� , ��Code #9 (pass) Not necessary Not necessary

Example: Cylinder 7 is weak

$�� )�� , ��Code #7 Code #9 (pass) Not necessary

Example: Cylinder 7 is very weak

$�� )�� , ��Code #7 Code #7 Code #9 (pass)

Example: Cylinder 7 is extremely weak or dead

$�� )�� , ��Code #7 Code #7 Code #7

��

9 System PASS

1 #1 Cylinder / Injector problem2 #2 Cylinder / Injector problem3 #3 Cylinder / Injector problem

4 #4 Cylinder / Injector problem5 #5 Cylinder / Injector problem6 #6 Cylinder / Injector problem

7 #7 Cylinder / Injector problem8 #8 Cylinder / Injector problem

77 Throttle was moved during test. Testing could not becompleted. Repeat test procedure starting from step 1.

13) Turn Ignition Key to Off Position

14) Disconnect Code Scanner

37

�� 62� � 9&��;��

• This test can help locate intermittentfaults in SOME circuits (see chart onpage 36).

• When Wiggle test is activated, theCode Scanner STO light and Audiotone will turn on if a problem isdetected.

• The STO light and tone are onlyenergized as long as the fault ispresent. If the problem goes away,the light and tone will turn off.

• If the STO light and tone come on asyou wiggle a sensor, connector orwiring, that’s where the problem is!

1) Safety First!




2) Make SureIgnition Keyis in OFFPosition

3) Check Code Scanner Battery





5) Put HOLD/TEST Switch in HOLDPosition

6) Put AUDIO Switch in ON Position

7) Turn Ignition Key to ON Positionbut DO NOT START ENGINE

8) Depending upon Vehicle ModelYear....

• 1986 & Older: “Wiggle Test” is nowactivated! Go to Step 9.

• 1987 & Newer:

—Without pausing, move HOLD/TEST switch to TEST then toHOLD and then back to TEST.

—“Wiggle Test” is now activated!Go to Step 9.

9) Perform “Wiggle Test” onSuspected Circuit

• Lightly tap sensor.

• Wiggle sensor connector.

• Twist and shake wiring betweensensor and computer.

• If the aboveactions recreatean intermittentfault, the STOlight will lightand a tone willsound for aslong as the faultis present. Thiscan help locate the area of anintermittent problem!

NOTE: If a fault is recreated this way,a service code will be stored incomputer memory. Be sure to erasethis code from memory after makingall repairs. Refer to Section 4 (Self-Test Part 5: Erasing “ContinuousMemory” codes).

10) Move Switches:

• HOLD/TEST switch to HOLD.

• AUDIO switch to OFF.

11) Turn Ignition Key to Off Position

12) Disconnect Code Scanner

TM

TEST

HOLD

CP 90

15 -

Ford

, Linc

oln &

Mer

cury

AUDIO

ON

OFF

38

�� :��;�� <

ACT ..............1984 & upBP ................1984 & upECT .............1984 & upEGO .............1990 & upEVP .............1984 & upIDM ..............1990 & up(DIS or dual plug DIS only)ITS ...............1990 & upMAF .............1990 & upMAP .............1984 & upPFE ..............1986 & up TP ...............1984 & upVAF ..............1985 & upVAT ..............1984 & up

39

��"��#��#�� .;�#��5

�� #��

��*� ��This section shows you how to use theCode Scanner for:

• Running tests of the engine computersystem.

• Reading service codes to pinpointproblem causes.

9�� 0— Read Sections 1 and 2 to learn about

service codes and the Code Scannertool.

— Read Section 3 to find the location ofthe Self- Test connector in yourvehicle. The connector type will tellyou whether you have an MCUsystem or an EEC-IV system.

— Read this section (7) if you have anMCU system. Use Section 4 if youhave an EEC-IV system.

��!�� The Self-Test procedure (also called“Quick Test”) involves engine off andengine running tests.

The entire procedure is summarizedbelow. Each part is fully explained onthe following pages. IMPORTANT: Allparts must be performed as shown foraccurate test results!

��.�� +� ��$0��+ �� • Safety First! Follow all safety rules.

• Perform Visual Inspection. This oftenreveals the problem.

• Prepare Vehicle. Check choke voltageand warm-up engine.

+� ��)0��=��&��&��.=&�&5��!��• Get service codes to help pinpoint

problems.

+� ��,0 ��=��&��.=&��5��!��• Get more service codes to pinpoint

problems found during engineoperating conditions.

��.�� !2��

1) Safety First!




• Make sure ignition key is in OFFposition.

2) Perform Visual Inspection.

Doing a thorough visual and “hands-on” underhood inspection beforestarting any diagnostic procedure isessential!! You can find the cause ofmany drivability problems by justlooking, thereby saving yourself a lotof time.

• Has the vehicle been serviced

40

recently? Sometimes things getreconnected in the wrong place, ornot at all.

• Don’t take shortcuts. Inspect hosesand wiring which may be difficult tosee because of location beneath aircleaner housings, alternators andsimilar components.

• Inspect the air cleaner and ductworkfor defects.

• Check sensors and actuators fordamage.

• Inspect all vacuum hoses for:– Correct routing. Refer to vehicleservice manual, or Vehicle EmissionControlInformation(VECI) decallocated in theenginecompart-ment.– Pinches and kinks.– Splits, cuts or breaks.

• Inspect wiring for:– Contactwith sharpedges. (Thishappensoften.)– Contactwith hotsurfaces, such as exhaust manifolds.– Pinched, burned or chafedinsulation.– Proper routing and connections.

• Check electrical connectors for:– Corrosion on pins.– Bent or damaged pins.– Contacts not properly seated inhousing.– Bad wire crimps to terminals.

HVAC/CRUISE

BRAKE BOOSTER

FUELPRESS

REG

EGRVACREG

EGRVACREG

TO TRANSMODE. ..

9RAC2LAB

FRONTOF CAR

GAP

.S.A.

STER

E M

S T

Bent Pins Corrosion

Problems with connectors arecommon in the engine control system.Inspect carefully. Note that someconnectors use a special grease onthe contacts to prevent corrosion. Do

not wipe off! Obtain extra grease, ifneeded, from your vehicle dealer. It isa special type for this purpose. Repairany problems found during the visualinspection and retest the vehicle. Ifthe original symptom is still present,continue the test. Go to Step 3,“Prepare Vehicle.”

3) Prepare Vehicle.

• Turn off all electrical equipment andaccessories in vehicle.

• Keep all vehicle doors closed duringtesting.

• Make sure radiator coolant andtransmission fluid are at properlevels.

• If the air cleaner must be removed(for example to measure the chokevoltage), leave all vacuum hosesattached to the air cleaner housing.

• Start the engine and allow it to idle.If the engine does not start, refer tothe “No Start” diagnostic procedurein the vehicle service manual.

WARNING: Always operate vehiclein a well ventilated area.

Do NOT inhale exhaust gases –they are very poisonous! Stay awayfrom moving parts!

• Check for power at the choke whilethe engine is running. Use avoltmeter to measure the voltagebetween the choke cap terminal andengine ground.

— Battery Powered Choke: voltageshould be about 12 volts.

— Alternator Powered Choke:voltage should be about 7.5 volts. Ifany problems are found in the chokepower circuit, make necessaryrepairs and re-do the Self-Testprocess starting with Step 1.Continue this procedure if noproblems are found.

• Allow the engine to idle until theupper radiator hose is hot andpressurized and RPM has settled towarm engine idle speed. Check forleaks around hose connections.

• Turn ignition key to OFF position.

41

4) Plug the Code Scanner into theVehicle Self-Test Connector.

• Refer to Section 3, “ConnectorLocation”. (The Self-Test connectoris near the MCU computer module.)

TM

TEST

HOLD

SELF

TEST

OUTPUT

ord,

Linc

oln &

Merc

ury

1981

& New

erAU

DIO

ON

Not used inMCU

systems

• Connect the Code Scanner to the 6-sided test connector only. The CodeScanner has a spot for a secondsmall connector, which is NOTUSED in MCU systems. Do notconnect anything to this unusedlocation.

• The Code Scanner will not harm thevehicle engine computer.

5) Do Special Set-Up Procedures.

The engine types listed requireadditional preparation beforecontinuing with the Self-Test.

In-Line 4 and 6 cylinder engineswith a canister control valve

Remove hose from connection port B.(This hose runs between the canistercontrol valve and the carbon canister.)Do NOT plug the hose for the remainderof the test procedure. Be sure toreconnect the hose after testing andservicing is completed!

V-6 and V-8 engines.

Remove PCV valve from breather capon valve cover. Be sure to replace PCVvalve after testing and servicing iscompleted!

2.3L engines with the GK code.

Remove the cap from the anti-backfirevacuum switch tee during testing. Theswitch is located behind the MCUmodule. Be sure to replace the cap aftertesting and servicing is complete!

2.3L engines with an EGR vacuum loadcontrol (wide open throttle) valve.

Cover the atmospheric vent holes with apiece of tape. Be sure to remove thetape after testing and servicing iscompleted!

Manifold Vacuum

Anti-backfirevacuum switch

Removecap

42

4.2L and 5.8L engines with a vacuumdelay valve.

There is a tee with a restrictor in theThermactor Vacuum control line. Therestrictor must be uncapped during thetest. Replace the cap after testing. Referto drawing for location of restrictor onthe TAD vacuum line (4.2L engines) orthe TAB vacuum line (5.8L engines).

6) Have a Pencil and Paper Ready.

• This is for writing down all thecodes.

7) Go to SELF-TEST PART 2: Key OnEngine Off (KOEO) Self-Test.

43

��.��324��04��1��.��

-;+&��/�0�>��!��+� ��$�� +� ��)�

1) Verify:

Ignition Key is in OFF Position andCode Scanner is Connected.


• Optional: Turn the AUDIO switch ON tohear “beeps” when the codes are sent.

3) Turn Ignition Key to ON Position butDO NOT START THE ENGINE.

• This starts the KOEO Self-Test.

• Codes are sent after 5 seconds.

• Pay no attention to a brief blink whichmay occur after ignition key is turnedto ON position.


Note: If the light does not flash, goback and repeat SELF-TEST PART 2starting with Step 1.

If the light still does not flash, you havea problem which must be repairedbefore proceeding. Refer to the vehicleservice manual “Self-Test NotFunctional” (or similar title) trouble-shooting chart.

• Count flashes to get service codes.(Each flash lasts 1/2 second.)

Code 12 looks like:


(FLASH = 1, FLASH FLASH = 2.(Put 1 and 2 together = code 12.)

Code 23 looks like:


• All codes are 2 digits long.

• The pause between each digit is 2seconds.

• After all codes are sent, the wholegroup is sent again just one moretime (so you can double check yourcode list).

• The longer pause between eachcode is 4 seconds.

Example of code 12 only:


(longer pause)


Example of code series 12 and 42:


(longer pause)

❊❊❊❊ PAUSE ❊❊FLASH FLASH FLASH FLASH (pause)

FLASH FLASH

(longer pause)


(longer pause)


FLASH FLASH



44

• Have your vehicle professionallyserviced. Codes indicate problemsfound by the computer.

or,

• Repair the vehicle yourself usingservice codes to help pinpoint theproblem. Refer to Test ResultsChart.

4��04��1��5��KOEO

CODES ACTION TO TAKE:

11* System pass. No problem found by computer during KOEO Self-(all except Test. Go to SELF-TEST PART 3: Key On Engine Running

high altitude) (KOER) Self-Test.

62* System pass. No problem found by computer during KOEO Self-(high altitude V-6 Test. Go to SELF-TEST PART 3: Key On Engine Running

or V-8 ONLY) (KOER) Self-Test.

65* System pass. No problem found by computer during KOEO Self-(high altitude Test. Go to SELF-TEST PART 3: Key On Engine Running

I-4 ONLY) (KOER) Self-Test.

Any Code(s) Codes indicate system problems are present now. Write down allcodes. Refer to vehicle service manual for code troubleshootingcharts and repair procedures. Repeat PART 2: Key On EngineOff (KOEO) Self-Test after every repair. Do not proceed to SELF-TEST PART 3 until a system pass code is received.

No Codes You have a problem which must be repaired before proceeding.Received Refer to the vehicle service manual “Self-Test Not Functional” (or(STO light similar title) troubleshooting chart.

alwayson or off)

*Note: “High Altitude” refers to vehicles with computer adjusted for operation at highelevations such as in Denver, Colorado.

45

��.�� 624��5�� 04��51��.��

-;+&��/�0�>��!��+� ��$��)�� +� ��,�

*� �8��"��-!4�7�-!?��0(Refer to page 44 for V-6 & V-8engines.)

1) Verify:

• Ignition Key is in OFF Position.

• Code Scanner is Connected.

• HOLD/TEST Switch is in TESTPosition.

WARNING: The next step involvesstarting the engine.

Observe safety precautions.

• Always operate vehicle in a wellventilated area.

Do NOT inhale exhaust gases –they are very poisonous!






3) Increase and Hold Engine Speed at3000 RPM Within 20 Seconds ofStart.

• Maintain engine speed at 3000RPM until service codes are sent(end of Step 5).


• Maintain engine speed at 3000RPM.


• Count flashes on the STO light.(Ignore any flashes lasting longerthan 1 second.)



Note: If the light does not flash orflashes the wrong number, go backand repeat SELF-TEST PART 3starting with Step 1. If the light stilldoes not flash correctly, you have aproblem which must be repairedbefore proceeding. Refer to thevehicle service manual “Self-Test NotFunctional” (or similar title) trouble-shooting chart.

5) Get Service Codes From theFlashing STO Light.

• Maintain engine speed at 3000RPM until codes are sent, thenrelease throttle and return to idleRPM.

• Count flashes on the STO light.This is done the same way as inSelf-Test Part 2. (Ignore any flasheslasting longer than 1 second.)

Code 12 looks like:




• After all codes are sent, the wholeseries is sent again just one moretime (so you can double check yourcode list).

46



(longer pause)


FLASH FLASH

(longer pause)


(longer pause)


FLASH FLASH


7) Remove Code Scanner.

*� �8��"��8!?�7�8!@��0(Refer to page 43 for I-4 and I-6engines.)

1) Verify:

• Ignition Key is in OFF Position.

• Code Scanner is Connected.

• HOLD/TEST Switch is in TESTPosition.

WARNING: The next step involvesstarting the engine. Observesafety precautions.

• Always operate vehicle in a wellventilated area.

Do NOT inhale exhaust gases –they are very poisonous!


• Put shift lever in PARK (automatictransmission) or NEUTRAL(manual transmission).




3) Warm-Up Engine.

• Allow engine to idle until it reachesnormal operating temperature.Then...

• Run engine at 2000 RPM for 2minutes.

4) Turn Engine Off, Then ImmediatelyRestart Engine and Allow to Idle.

Note: Vehicles with Throttle Kickeractuator – the Throttle Kicker willextend (increasing RPM) and remainso throughout the test.



• Count flashes on the STO light.(Ignore any flashes lasting longerthan 1 second.)



Note: If the light does not flash orflashes the wrong number, go back andrepeat SELF-TEST PART 3 startingwith Step 1. If the light still does notflash correctly, you have a problemwhich must be repaired beforeproceeding. Refer to the vehicle servicemanual “Self-Test Not Functional” (orsimilar title) troubleshooting chart.

6) Test Knock Sensor (if used onvehicle).

• If vehicle does not use knock sensor,skip this step and go to Step 7.

• Do the following immediately afterengine ID code is sent:

– Simulate spark knock by placing a3/8 inch socket extension (or similartool) on manifold near base of knocksensor.

47

– Tap onend ofexten-sionwith alight (4oz.)hammer for 15 seconds.

– DO NOT TAP SENSOR!

7) Get Service Codes From theFlashing STO Light.

• Count flashes on the STO light. Thisis done the same way as in Self-TestPart 2. (Ignore any flashes lastinglonger than 1 second.)

Code 12 looks like:




• After all codes are sent, the wholegroup is sent again just one moretime (so you can double check yourcode list).



(longer pause)


FLASH FLASH

(longer pause)


(longer pause)


FLASH FLASH


9) Remove Code Scanner.


• Have your vehicle professionallyserviced. Codes indicate problemsfound by the computer.

or,

• Repair the vehicle yourself usingservice codes to help pinpoint theproblem. Refer to Test Results Chart.Code definitions are listed in Section8, “Code Meanings (MCU system).”

48

4��5�� 04��51��5��KOER

CODES ACTION TO TAKE:

11* System pass. No problem found by computer during KOER Self-(all except Test. The Self-Test Diagnostic Procedure is complete. If vehicle

high altitude) symptoms are still present, they are probably not related to thecomputer system.

62* System pass. No problem found by computer during KOER Self-(high altitude V-6 Test. The Self-Test Diagnostic Procedure is complete. If vehicle

or V-8 ONLY) symptoms are still present, they are probably not related to thecomputer system.

65* System pass. No problem found by computer during KOER Self-(high altitude Test. The Self-Test Diagnostic Procedure is complete. If vehicle

I-4 ONLY) symptoms are still present, they are probably not related to thecomputer system.

Any Code(s) Codes indicate system problems are present now. Write down allcodes. Refer to vehicle service manual for code troubleshootingcharts and repair procedures. Repeat PART 3: Key On EngineRunning (KOER) Self-Test after every repair.

No Codes You have a problem which must be repaired before proceeding.Received Refer to the vehicle service manual “Self-Test Not Functional” (or(STO light similar title) troubleshooting chart.

alwayson or off)

*Note: “High Altitude” refers to vehicles with computer adjusted for operation at highelevations such as in Denver, Colorado.

49

�� *&��;�#�� .;�� #��5

�� • Many of the codes

listed may not apply toyour vehicle.

• Use the definition thatapplies to your enginetype: In-Line 4 or 6cylinder (I-4, I-6) or V-6or V-8.

• Follow vehicle servicemanual procedures tofind the cause of thecode.

Remember:

1) Visual inspections areimportant!



��“High Altitude” computeradjusted for operation athigh elevations such as inDenver, Colorado.��(All except HighAltitude): System pass.��(High Altitude only):Altitude (ALT) circuit isopen.��System pass.��(All except High Altitude):System pass.��(High Altitude only):Altitude (ALT) circuit isopen.��(All except High Altitude):System pass.��(High Altitude only):Altitude (ALT) circuit isopen.� ��RPM out ofspecification – ThrottleKicker (TK) system. "��Knock Sensor (KS)signal not detected duringKey On Engine Run(KOER) Self-Test.�� Key OnEngine Run (KOER) Self-Test not initiated.!�� ExhaustGas Oxygen (EGO)sensor: voltage signalalways “lean” (low value) –does not switch.! �� ExhaustGas Oxygen (EGO)sensor: voltage signalalways “rich” (high value) –does not switch.!!�� ExhaustGas Oxygen (EGO)sensor: signal voltageindicates “rich” (high value)with Thermactor airswitched upstream to theexhaust manifold (a “lean”air/fuel condition).!"�� Thermactorair flow is always upstream(going to exhaust

manifold).!�� ThermactorAir System unable tobypass air (vent toatmosphere)."��Low or MidTemperature Switch circuitis open when engine is hot.��Low TemperatureVacuum Switch circuit isopen when engine is hot.�� Hi or Hi/Low VacuumSwitch circuit is alwaysopen.�� Hi or Hi/Low VacuumSwitch circuit is alwaysopen." ��(car): Idle TrackingSwitch (ITS) – voltage doesnot change from closed toopen throttle. (Closedthrottle checked during KeyOn Engine Off condition.Open throttle checkedduring Engine Runningconditions.)I-4 (truck): Idle/DecelVacuum Switch circuitalways open.�� Wide Open Throttle(WOT) Vacuum Switchcircuit is always open."�� Wide Open Throttle(WOT) Vacuum Switchcircuit is always open.�� CROWD VacuumSwitch circuit is alwaysopen.�� Dual TemperatureSwitch circuit is alwaysopen.�� Dual TemperatureSwitch circuit is alwaysopen."!�� Mid TemperatureSwitch circuit is alwaysopen.�� Mid TemperatureSwitch circuit is alwaysopen.""�� Road Load VacuumSwitch circuit is alwaysopen.

50

�� Mid Vacuum Switchcircuit is always open.�� Mid Vacuum Switchcircuit is always open."�� Closed ThrottleVacuum Switch circuit isalways open.�� Hi/Low VacuumSwitch circuit is alwaysclosed.�� Hi/Low VacuumSwitch circuit is alwaysclosed.� �� “High Altitude”refers to vehicles withcomputer adjusted foroperation at high elevationssuch as in Denver,Colorado.��(car): Idle TrackingSwitch (ITS) circuit isclosed at idle.��(truck): Idle/DecelVacuum Switch circuit isalways closed.�� Wide Open Throttle(WOT) Vacuum Switchcircuit is always closed.��(All except High Altitude):Altitude (ALT) circuit isopen.��(High Altitude only):System pass.��(All except HighAltitude): Altitude (ALT)

circuit is open.��(High Altitude only):System pass.�� Wide Open Throttle(WOT) Vacuum Switchcircuit is always closed.�� CROWD VacuumSwitch circuit is alwaysclosed.�"�� “High Altitude” refersto vehicles with computeradjusted for operation athigh elevations such as inDenver, Colorado.��(All except High Altitude):Altitude (ALT) circuit isopen.��(High Altitude only):System pass.��Mid Vacuum Switchcircuit is always closed.��Mid Vacuum Switchcircuit is always closed.�� Closed ThrottleVacuum Switch circuit isalways closed.

51

��$"�� )� ��*�! ��&��&��+

��!-8��;�#This section explains the EEC-IV enginecomputer control system, the types ofsensors and how the computer controlsfuel delivery, idle speed, spark timingand emission devices. The MCU systemis described later, but this entire sectionmust still be read for complete under-standing.

The following is an introduction tocomputer controlled engine systems.Additional information may be found inbooks dealing with this subject availableat your local library or auto parts store.The more you know about the computersystem, the better and faster you cantroubleshoot and fix problems.

"�� AComputer controls were installed invehicles to meet Federal Governmentregulations for lower emissions andbetter fuel economy. This all began in theearly 1980’s when purely mechanicalcontrol systems just were not goodenough anymore. A computer could beprogrammed to precisely control theengine under various operatingconditions and eliminate some mechani-cal parts making the engine morereliable.

"�� The main control areas of the computerare:

• Fuel delivery

• Idle speed

• Spark advance timing

• Emission devices (EGR valve, carboncannister, etc.)

The changes made to the basic engineto allow a computer to control thesetasks are the only differences betweenan older engine and a computerized one.A little later we will discuss just how thecomputer handles these tasks.

"��/&��AA computer controlled engine is basicallythe same as earlier types. It is still aninternal combustion engine with pistons,spark plugs, valves and cams. Theignition, charging, starting, and exhaustsystems are almost the same, as well.You test and repair these systems thesame way as before, using familiar tools.The instruction manuals for these toolsshow you how to perform the tests. Yourcompression gauge, vacuum pump,dwell-tach meter, engine analyzer, timinglight, etc., are still valuable!

�� The computer module is the “heart” ofthe system. It is sealed in a metal boxand linked to the rest of the system by awiring harness. The computer module islocated in the passenger compartment,usually behind the dashboard or frontkick panels. This protects the electronicsfrom moisture, extreme temperaturesand excess vibration, which are commonin the engine compartment.

The computer is permanently pro-grammed by factory engineers. Theprogram is a complex list of instructionstelling the computer how to control theengine under various driving conditions.To do its job, the computer needs toknow what is happening and then itneeds devices to control things.

�� The computer can only work withelectrical signals The job of the sensor isto take something the computer needs toknow, such as engine temperature, andconvert it to an electrical signal which thecomputer can understand. You can thinkof sensors as “high tech” senders thedevices found in older vehicles forgauges and dashboard message lights

52

(oil pressure, fuel level, etc.)Signals running into the computerare referred to as “inputs.”

Sensors monitor such things as:

• Engine temperature

• Intake manifold vacuum

• Throttle position

• RPM

• Incoming air (temperature, amount)

• Exhaust gas oxygen content

• EGR Valve flow

Most engine computer systems will usethe sensor types listed above.Additional sensors may be useddepending upon the engine, vehicletype or other tasks the computer mustdo. Note that information from onesensor may be used by the computerfor many different tasks. For example,engine temperature is something thecomputer needs to know whencontrolling fuel delivery, spark timing,idle speed and emission systems. Thesensor information may be veryimportant for one engine controlfunction, but only used to “fine tune” asecond one.

�� • Thermistor – This is a resistor whose

resistance changes with temperature.It is used to measure temperatures ofcoolant or incoming air. It has twowires connected to it.

• Potentiometer – This signals aposition, such as throttle position orEGR valve position. It connects tothree wires: one for power, one forground and one to carry the positionsignal back to the computer.

• Switches – These are either ON(voltage signal to the computer) or

OFF (no voltage signal to thecomputer). Switches connect to twowires and tell the computer simplethings, such as whether or not the air

conditioner is running.

• Signal Generator – These createtheir own signal to tell thecomputer of some condition, suchas exhaust gas oxygen content,camshaft position, or intakemanifold vacuum. They may have

one, two or three wires connected tothem.

�� The computer can only send outelectrical signals (referred to as“outputs”). Devices called actuators arepowered by the computer to controlthings. Actuator types include:

• Solenoids – These are used to controla vacuum signal, bleed air, control fuelflow, etc.

• Relays – These switch high amperagepower devices on and off, such aselectric fuel pumps or electric coolingfans.

• Motors – Small motors are often usedto control idle speed.

&�� Not all of the computer outgoing signalsgo to actuators. Sometimes information issent to electronic modules, such asignition or trip computer.

%�� *�� Operation and emission performancedepend upon precise fuel control. Earlycomputer controlled vehicles usedelectronically adjustable carburetors, butfuel injectors were soon introduced.

The job of the computer is to provide theoptimum mixture of air and fuel (air/fuelratio) to the engine for best performanceunder all operating conditions.

The computer needs to know:

• ...what the engine operating condition

OUTP

UT

ACTU

ATORS

SENSORS INPUT

ECA BRAINS OF THE

COMPUTER

53

is. Sensors used: coolant tempera-ture, throttle position, manifoldabsolute pressure, mass air flow,RPM.

• ...how much air is coming into theengine. Sensors used: mass air flowor a combination of manifold absolutepressure, manifold air temperature,RPM.

• ...how much fuel is being delivered. Thecomputer knows this by how long itturns on the fuel injectors. (Thecomputer uses a “feedback control” or“duty cycle” solenoid on electroniccontrolled carburetors.)

• ...that everything is working the way itshould. Sensor used: exhaust gasoxygen sensor.

Note: Not all engines use every sensorlisted above.

�� !��“Open Loop” operation

The coolant temperature sensor tells thecomputer how warm the engine is.Factory engineers know what the bestair/fuel mixture is for the engine atvarious operating temperatures. (Morefuel is needed for a cold engine.) Thisinformation is permanently programmedinto the computer. After the computerknows the engine temperature, itdetermines the amount of air coming in,then it will look at its programming to findout how much fuel to deliver and operatethe fuel injectors accordingly. (Engineswith feedback carburetors don’t do anyof this. They use a “Variable VoltageChoke.” The computer controls theamount of choke opening.)

This is an example of “Open Loop”operation by the computer. The controlsystem performs an action (expecting acertain result), but has no way ofverifying if the desired results wereachieved. In this case, the computerpulses a fuel injector expecting a certainamount of fuel to be delivered. (Thecomputer assumes everything in the fuelsystem is operating as expected.) Inopen loop operation, the computer hasno way of checking the actual amount offuel delivered. Thus, a faulty injector orincorrect fuel pressure can change the

amount of fuel delivered and thecomputer would not know it.

%�� “Closed Loop” operation

The computer watches the coolanttemperature and throttle position sensorsto tell when the engine is all warmed upand cruising. As before, the computerdetermines the amount of air coming intothe engine, then delivers the amount offuel that should provide the optimum air/fuel mixture. The big difference is thatthis time the computer uses the oxygensensor to check how well it’s doing andreadjust things, if needed, to make surethe fuel delivery is correct.

This is an example of “Closed Loop”operation. The control system performsan action (expecting a certain result),then checks the results and corrects itsactions (if necessary) until the desiredresults are achieved.

The oxygen sensor only works when it isvery hot. Also, it can only monitor the“hot engine” air/fuel mixture value andsend back a signal to the computer. Thesensor can not monitor the other air/fuelmixture values used during enginewarm-up, so the computer must operate“open loop” at that time.

�� B�� 7�-��As long as the engine and oxygensensor are hot, the computer canoperate “closed loop” for best economyand least emissions. During the driveconditions listed above, the computermay have to ignore the sensor and run“open loop,” relying on internal program-ming for fuel delivery instructions. Duringidle, for example, the oxygen sensor maycool down and stop sending a signal. Adifferent situation can occur during wide-open-throttle acceleration. The computersometimes adds additional fuel (onpurpose) for temporary accelerationpower. The computer knows it is running“rich” so it ignores the sensor signal untilthe wide-open-throttle condition is over.

54

%�� -��Throttle position and RPM sensors tellthe computer when the vehicle is idling.(Sometimes an idle position switch on thethrottle is used.) The computer merelywatches RPM and adjusts an idle speedcontrol device on the vehicle to maintainthe desired idle condition. Note that thisis another example of “closed loop”operation. The computer performs anaction (activating an idle control device),then watches the results of its action(engine RPM) and readjusts asnecessary until the desired idle speed isachieved.

There are two types of idle speedcontrol devices. The first is an adjust-able throttle stop that can be positionedby a computer controlled motor. Thesecond method allows the throttle toclose completely, then has a computercontrolled solenoid to pass air aroundthe closed throttle to set the idle speed.

Smaller engines can stumble or stall atidle when the air conditioner compres-sor turns on or the power steering isused. To prevent this, switches tell thecomputer when these demands arecoming so it can increase the idleaccordingly.

A simple form of idle speed adjustmentusing a “throttle kicker” actuator is usedon early EEC-IV V-8 engines. Thisdevice is described later in the MCUsection.

%�� You set spark timing in a non-computerengine by using a timing light andadjusting the distributor at idle RPM.During vehicle operation, timing ischanged by either engine vacuum(vacuum advance function) or by engineRPM (centrifugal advance function.)These spark timing changes are donemechanically inside the distributor.

Computer controlled vehicles using adistributor still have you set spark timingby using a timing light and adjusting thedistributor at idle RPM. The timingchanges which occur during vehicleoperation, however, are controlledelectronically. The computer looks at

sensors to determine vehicle speed,engine load and temperature. (RPM,throttle position, coolant temperatureand manifold pressure or mass air flowsensors are used.) Then, the computeradjusts timing according to factoryprogrammed instructions. Some vehicleshave a “knock” sensor. The computercan “fine tune” the spark timing if thissensor signals an engine knockcondition. A timing advance signal issent by the computer to an ignitionmodule which eventually creates thespark.

�� • EGR Valve – The EGR valve lets

exhaust gases re-enter the intakemanifold and mix with the incoming air/fuel. The presence of exhaust gasesreduces combustion temperatures inthe cylinders and this reducespoisonous NOx emissions. Thecomputer controls the flow of gasesthrough the EGR valve. The EGRsystem is only used during warmengine cruise conditions. A partiallyopen EGR valve at other times cancause stalling.

• Thermactor Air System – This systemworks with the catalytic convertor. Thecomputer takes outside air from an airpump and directs it to the exhaustmanifold or catalytic convertor asnecessary for best emissionperformance. Refer to “Thermactor AirSystem” in Reference Glossary formore explanation.

• Fuel Evaporation Recovery System –A special canister collects vaporsevaporating from the fuel tank,preventing them from escaping intothe atmosphere and causing pollution.During warm engine cruise conditions,the computer draws the trappedvapors into the engine for burning.(See “CANP” in Reference Glossary.)

&�� The computer controls other odd jobslike handling “speed control” andtransmission torque convertor lock-upand shifting functions. Detailedexplanations may be found in yourvehicle service manual.

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;� �� The Reference Glossary describes thevarious sensors and actuators used inthe EEC-IV and MCU systems. You canlearn more by reading these definitions.

�<��:�,��+��:.;� �� C5The MCU system is similar (but simpler)than the EEC-IV version just described.The MCU computer module is located inthe engine compartment. The MCU usessensors to monitor engine operation andactuators to control things.

"��;�#�� The original MCU just controls fueldelivery (Air/Fuel ratio) and theThermactor Air System. Features addedlater included limited control of idlespeed, spark timing retard and fuelevaporation canister. To do these tasks,the MCU needs information aboutengine temperature, throttle position,tach signal and knock conditions.

How MCU measures Engine Tempera-ture

• Some MCU systems use a singleelectrical switch (“Low TemperatureSwitch”). The switch is activated byvacuum. The vacuum comes from a“Ported Vacuum Switch” which istemperature controlled. When enginetemperature reaches a certain value,the Ported Vacuum Switch sendsvacuum to the Low TemperatureSwitch, which toggles and sends asignal to the MCU computer. The LowTemperature and Ported Vacuumswitches may be separate units orcombined into one assembly.

• Other MCU systems use twoswitches: Mid and Dual Temperature.The Mid Temperature Switch is similarto the Low Temperature Switch. TheDual Temperature Switch sends asignal when engine temperature iseither cold OR very hot.

How MCU measures Throttle Position

• Some MCU systems use an IdleTracking Switch. This is an electricalswitch mounted near the throttlelinkage on the carburetor. The switchis open when the throttle is resting inidle position. The switch closes assoon as the throttle is moved off idle.A Wide-Open-Throttle (WOT) VacuumSwitch is also used. Weak manifoldvacuum due to WOT operation causesthe WOT Vacuum Switch to send asignal to the MCU computer.

• Other versions of MCU monitorengine vacuum to sense idle (highvacuum), cruise (moderate vacuum)or WOT (low vacuum) conditions.Vacuum operated electrical switchesare used. The switches toggle atvarious vacuum levels and sendsignals to the MCU computer. Theseparts are sometimes called “Low”,“Mid” and “High” vacuum switches (a“Zone Vacuum Switch” assembly).Other names are “Wide-Open-Throttle”, “Crowd” and “ClosedThrottle” vacuum switches.

�� The MCU system monitors this ignitionsignal to measure engine RPM. A wireconnects the computer to the Tachterminal on the ignition coil. Thecomputer watches RPM to insuresmooth operation when the air/fuelmixture is changed.

=�� Some MCU systems have a KnockSensor which sends a pulse signal to thecomputer when an engine knockcondition occurs.

%��;�#�� *�� The MCU computer controls air/fueldelivery using a “Feedback Carburetor”.The choke and idle cam mechanismsare similar to those on a conventionalcarburetor.

• One version has the computercontrolling a fuel metering rod insidethe carburetor. The computer controls

56

an electric motor (“FeedbackCarburetor Actuator”) to position thisrod.

• Another method uses a fuel meteringrod positioned by vacuum. Thecomputer controls vacuum to this rodby using a “Vacuum RegulatorSolenoid”. The computer sends aduty cycle signal (see definition inReference Glossary) to the solenoidto vary vacuum.

• A third version has the computercontrolling air into the carburetor idleand main system vacuum passages.A “Feedback Control Solenoid” isused to control air entry. A duty cyclesignal from the computer controls thissolenoid to vary air flow.

%�� “Closed Loop” operation

The computer uses the enginetemperature and throttle positioninformation to tell when the engine is allwarmed up and cruising. At this time thecomputer will use the Exhaust GasOxygen sensor to run the engine in a“closed loop” mode for minimumemissions and best fuel economy.

�� B�� B�� -��“Open Loop” operation

The computer runs the engine in an“open loop” mode when sensorinformation signals one of the drivingconditions listed above. The computerrelies on factory programmed instruc-tions to determine the proper air/fuel

mixture to deliver.

;�#��D��The MCU system does not control idlespeed – a standard mechanical idle cammechanism is used. However, someMCU systems have a vacuum operated“Throttle Kicker” actuator. The computeruses this device to push the throttlelinkage off idle position when additionalidle RPM is required. This happenswhen sensors indicate a cold start orengine overheat condition. Thecomputer energizes a “Throttle KickerSolenoid” to apply vacuum to theactuator.

;�#�� The MCU system does not control sparktiming – a standard distributor is used.However, some MCU systems can senda signal to retard timing if the knocksensor indicates an engine knockcondition. The computer energizes a“Spark Retard Solenoid” to bleed controlvacuum from the distributor advance toretard the ignition timing.

;�#�� • Thermactor Air System – All MCU

vehicles have this system which issimilar to the one discussed earlier inthis section. The MCU uses enginetemperature throttle positioninformation to determine properoperation of the thermactor system.

• Fuel Evaporation Recovery System –This system is similar to the onediscussed earlier in this section. It isonly used on some MCU vehicles.The MCU uses engine temperatureand throttle position information todetermine proper operation of thissystem.

57

�!� �� #&'�Air conditioner&��Air Conditioner Clutchsignal. This tells the ECAthat either the A/Ccompressor is running orthat A/C operation is beingrequested (depends uponvehicle).&�(Air Charge Temperaturesensor. This sensor is athermistor – a resistorwhose resistancedecreases withtemperature. It is threadedinto the intake manifold sothe ECA can determine thetemperature of theincoming air. This is usedfor fuel deliverycalculations.&�� Devices which are poweredby the ECA to controlthings. Actuator typesinclude relays, solenoidsand motors. Actuators allowthe ECA to control engineoperation.&')Air/fuel.&�*�Air Management solenoid#1. Also called TABsolenoid. (See TAB forexplanation.)&�* Air Management solenoid#2. Also called TADsolenoid.(See TAD definition.)&+,-Automatic Transaxle withOverdrive gear..,,Brake On-Off switch signal.Tells the ECA when thebrakes are being applied../Barometric Pressuresensor. (See MAPdefinition.)

�&0/Canister Purge solenoid.This device controls theflow of fuel vapors from thecanister to the intakemanifold. The canistercollects vapors evaporatingfrom the fuel tank,preventing them fromescaping into theatmosphere. During warmengine cruise conditions,the ECA energizes CANPso the trapped vapors aredrawn into the engine andburned.��Converter Clutch solenoid.Located in certainelectronically controlledtransmissions. The ECAuses this solenoid tocontrol the lock-up clutch inthe torque converter. TheECA will engage or releaselock-up depending uponengine operation.��1Coast Clutch Solenoid.Located in certainelectronically controlledtransmissions. The ECAuses this solenoid to permitengine braking duringdeceleration when in thirdgear (with gear shift lever inDrive).��,Converter Clutch Overridesolenoid. Located insidetransmission havingmechanically controlledlock-up torque converter.The ECA uses this solenoidto disable lock-up undercertain engine operatingconditions.�)�Central Fuel Injection. Afuel injection system havingone (or two) injectorsmounted in a centrallylocated throttle body, asopposed to positioning theinjectors close to an intakevalve port.

��-Cylinder Identification signal.This is a frequency typesignal coming from acamshaft mounted sensor.The ECA uses this signal toreference fuel injectoroperation and synchronizespark plug firing ondistributorless ignitions.��2��3�'24This is when a controlsystem performs an action(expecting a certain result),then checks the results andcorrects its actions (ifnecessary) until the desiredresults are achieved.Example: The ECA pulses afuel injector expecting acertain amount of fuel to bedelivered. In closed loopoperation, the ECA uses asensor to check the actualamount of fuel delivered.The ECA will correct theinjector pulse width asnecessary to obtain thedesired fuel delivery.��An unbroken, continuouscircuit through which anelectric current can flow.�� (�� 15��6�Used on MCU systems.These are vacuum controlledelectrical switches whichsignal various engineoperating temperatures tothe MCU module. A portedvacuum switch is used alongwith the temperatureswitches. The normallyclosed ported vacuumswitches open at a specifictemperature and allowvacuum to pass. Thisvacuum then causes thetemperature switches toswitch and send a signal tothe MCU module. SomeMCU systems use a singleLow Temperature Switch totell the MCU module whenthe engine has warmed up.Other MCU systems use twoswitches: one for midtemperature and a secondfor high/low temperatures(the switch will signal whenthe temperature is either toohigh or too low). The MCUmodule uses temperature

58

information when controllingfuel delivery, Thermactor AirSystem, spark retard,throttle kicker and canisterpurge.�/1Crankshaft PositionSensor. This crankshaftmounted sensor sends afrequency signal to theECA. (See PIP signaldefinition.) It is used toreference fuel injectoroperation and synchronizespark plug firing ondistributorless ignitions.�1Clutch switch.��. � ��(��A diagnostic Self-Test onlyused on SequentialElectronic Fuel Injector(SEFI) engines. The testturns each injector on andoff to check if they areclosed or damaged.-�2Data Communication Link.A two wire circuit used bythe ECA to exchangeinformation with othercomputer controlledmodules.-�� 1�� An electronic signal whichhas only two (2) voltagevalues: a “low” value (closeto zero) and a “high” value(usually 5 volts or greater).Sometimes the low voltagecondition is called “Off” andthe high voltage conditionis called “On”. Signalswhich can have anyvoltage value are called“analog” signals.-�1Distributorless IgnitionSystem. In general use,this refers to a systemwhich produces the ignitionspark without the use of adistributor. Ford technicalmanuals use DIS whenreferring to a particulardistributorless ignitionsystem where the ECAdirectly controls timing ofspark firing. (Compare toEDIS definition.)-��7�A transistor “switch” insidethe ECA used to applypower to an externaldevice. This allows theECA to control relays,solenoids and smallmotors.

-��A term applied to frequencysignals – those which areconstantly switchingbetween a small voltagevalue (close to zero) and alarger value (usually 5 voltsor greater). Duty cycle isthe percentage of time thesignal has a large voltagevalue. For example, if thesignal is “high” (largevoltage) half of the timethen the duty cycle is 50%.If the signal is “high” onlyone fourth of the time, thenthe duty cycle is 25%. Aduty cycle of 0% means thesignal is always at a “low”value and not changing. Aduty cycle of 100% meansthe signal is always at a“high” value and notchanging. The enginecontrol computer uses dutycycle type signals when itwants more than just “on-off” control of an actuator.This is how it works: A 50%duty cycle signal going to avacuum switching solenoidmeans the solenoid will be“on” (passing full vacuum)half the time and “off”(passing no vacuum) halfthe time. The averageamount of vacuum passingthrough the solenoid will beone half of the full valuebecause the solenoid isonly “on” for one half of thetime. (The signal switchesat a rapid rate, such as tentimes a second.) Thus, thecomputer can get avacuum controlled actuatorto move half way between“no vacuum” position and“full vacuum” position.Other positions can beachieved by changing theduty cycle of the controlsignal which in turnchanges the averageamount of control vacuum.

-8�Digital Volt Meter. An instru-ment using a numeric read-out to display measuredvoltage values as opposedto a moving needle on agauge face. Usually theinstrument has other mea-suring capabilities, such asresistance and current, andmay be called a DMM(Digital Multi-Meter). MostDVM’s have 10 Megohminput impedance. This meansthe circuit under test will notbe electronically disturbedwhen the DVM is connectedfor a measurement.-�� 9��A user action expected bythe ECA during the courseof a diagnostic Self-Test.Normally, this meansperforming a brief wide-open-throttle action duringthe Engine Running Self-Test. The ECA sends asingle voltage pulse throughthe STO circuit (making ablink on the Code ScannerLED) signaling the user toperform the DynamicResponse action.��&Electronic ControlAssembly. The “brains” ofthe engine control system. Itis a computer housed in ametal box with a number ofsensors and actuatorsconnected with a wiringharness. Its job is to controlfuel delivery, idle speed,spark advance timing andemission systems. The ECAreceives information fromsensors, then energizesvarious actuators to controlthe engine. Sometimesvehicles have additionalcomputers controlling otherfunctions. These includeanti-lock brake and activesuspension systems.��(Engine Coolant Temperaturesensor. This sensor is athermistor – a resistor whoseresistance decreases withincreases in temperature.The sensor is threaded intothe engine block andcontacts the engine coolant.The ECA uses this signal forcontrol of fuel delivery, sparkadvance, EGR flow andother emission controldevices.

59

�-)Electro-Drive Fan relay.The ECA energizes thisrelay to apply power to theElectro-Drive Fan (mountedin frontof the radiator) for enginecooling purposes. The fanis only turned on when theECA determines cooling isnecessary.�-�1Electronic DistributorlessIgnition System. Fordtechnical manuals useEDIS when referring to aparticular distributorlessignition system where aseparate module (EDISmodule) directly controlsspark firing andsynchronization. All theECA does is send a signalrequesting a particularspark timing based onengine operation. (Refer toSAW definition.) The EDISmodule and associatedsensors take care of allother aspects of ignitionsystem operation.��*�8Electronic Engine Controlsystem, version 4. Thename for Ford’scomputerized enginecontrol system used onvehicles starting in 1983.The system consists of acontrol module (ECA)containing a computer, andseveral different sensorsand actuators. The systemcontrols fuel delivery, idlespeed, ignition timing andvarious emission devices.�)�Electronic Fuel Injection. Incommon usage, this termapplied to any systemwhere a computer controlsfuel delivery to an engineby using fuel injectors. InFord vehicle usage, an EFIsystem is one using oneinjector for each cylinder.The injectors are mountedin the intake manifold. Theinjectors are fired in groups(“banks”). Usually allinjectors on one side of theengine are fired together.Injectors are firedindividually in SFI engines(see SFI definition).

�:,Exhaust Gas Oxygensensor. The EGO sensor isthreaded into the exhaustmanifold, directly into thestream of the exhaustgases. The ECA uses thesensor to “fine tune” fueldelivery. The sensorgenerates a voltage of 0.6to 1.1 volts when theexhaust gas is rich (lowoxygen content). Thevoltage changes to 0.4volts or less when theexhaust gas is lean (highoxygen content). Thesensor only operates afterit reaches a temperature of349°C (660°F).�:9Exhaust Gas Recirculation.The EGR systemrecirculates exhaust gasesback into the intakemanifold to reduce NOxemissions. Various types ofsystems are in use ondifferent vehicles. Usuallythe ECA directly controlsEGR flow, but on somevehicles it may just activatea system controlled by non-electronic means. Vacuumcontrolled EGR valves arenormally closed. Applyingvacuum opens the valve.�:9*�EGR Control solenoid. Usedin certain EGR systems.The ECA energizes thisactuator to apply vacuum(and thus open) the EGRvalve. Used along with theEGR-V solenoid.�:9�1',EGR valve Shut-Offsolenoid. Used inmechanically operatedEGR systems where theECA does not control EGRflow. The ECA cancompletely stop flow byenergizing this solenoid, ifengine operating conditionsrequire this.�:9*8EGR Vent solenoid. Usedin certain EGR systems.The ECA energizes thisactuator to vent vacuum(and thus close) the EGRvalve. Used along with theEGR-C solenoid.

�;�Exhaust Heat Controlsolenoid. The ECAenergizes this solenoid toapply vacuum (and thusactivate) the EHC valve.When activated, this valvediverts hot gases from theexhaust manifold to theintake manifold heat riserpad. Heat is transferredfrom the exhaust gas to theriser pad, which in turnheats the incoming air. Thisaids in fuel atomization forbetter combustion efficiencyduring engine warm-up.��Electronic InstrumentCluster. A vehicle instrumentpanel using electronicdisplays (numbers or bargraph type) in place ofstandard gauges. Receivesinformation from the ECA byusing the DataCommunications Link (DCL).��ElectromagneticInterference. Undesiredsignals interfering with aneeded signal. Forexample: static on a radiobrought about by lightningflashes or closeness tohigh voltage power lines.�/�Electronic Pressure Controlsolenoid. Located in certainelectronically controlledtransmissions. Used by theECA to set hydraulic linepressures inside thetransmission – for soft orfirm shifting (dependingupon vehicle acceleration).�8/EGR Valve Position sensor.This sensor is mounted ontop of the EGR valve. Itmonitors the position of theEGR valve stem (that is,how far the valve is open).This signal allows the ECAto calculate EGR flow atany time.�89EGR Vacuum Regulatorsolenoid. This solenoid iscontrolled by a duty cyclesignal from the ECA and isused to vary the amount ofvacuum applied to the EGRvalve. The solenoid notonly controls the vacuum, italso functions as a vent toallow the EGR valve toclose. The ECA controlsthe amount of EGR valveopening by adjusting thevacuum being applied.(See Duty Cycle definition.)

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).�Feedback Carburetor. Thisis used on early versions ofcomputer controlledengines. It is a carburetorwhich can have its air/fueldelivery modified by anelectronic signal from theECA. Three versions areused. See definitions forFBCA, FCS and VRS.).�&Feedback CarburetorActuator. Used onfeedback carburetors –those where the enginecomputer controls the air/fuel ratio.The FBCA is a steppermotor (see Stepper Motordefinition). It controls ametering assembly in thecarburetor which can varythe amount of air enteringthe main discharge area.The computer uses FBCAto vary this metered air andcontrol air/fuel mixturesanywhere from “rich” to“lean”.)�1Feedback Control Solenoid.Used on feedbackcarburetors – those wherethe engine computercontrols the air/fuel ratio.This solenoid receives aduty cycle signal from thecomputer. (See Duty Cycledefinition.) The solenoidintroduces fresh air fromthe air cleaner into the idleand main system vacuumpassages. A low duty cyclesignal reduces air passingthrough the solenoid for“rich” operation. A high dutycycle signal increases airpassing through thesolenoid for “lean”operation.)��Failure Management andEffects Mode. The namegiven to the way the ECAoperates when failures aredetected in sensor or actuatorcircuits and normal operationis no longer possible. TheECA runs the engine the bestway it can until the vehicledriver can get the problemrepaired. The effect on engineperformance can be slight orsevere.

)�<��The frequency of anelectronic signal is ameasure of how often thesignal repeats a voltagepattern in a one secondtime span. For example:suppose a signal starts atzero volts, goes to fivevolts then returns to zeroagain. If this patternrepeats itself 100 times inone second, then the signalfrequency is 100 cycles persecond – or 100 Hertz.)��=��An electronically controlledflow valve. Fuel injectorsare connected to apressurized fuel supply.(The pressure is created bya fuel pump.) No flowoccurs when the injector isoff (not energized). Whenthe injector is powered, itopens fully allowing the fuelto flow. The ECA controlsfuel delivery by varying theamount of time the injectorsare turned on.)/Fuel Pump relay. The ECAenergizes this relay toapply power to the vehiclefuel pump. For safetyreasons, the ECA removespower from the fuel pumpwhen ignition signals arenot present.)/�Fuel Pump Monitor signal.This is a wire between theECA and the fuel pumpmotor power terminal. TheECA uses this signal toverify when voltage is atthe fuel pump (fordiagnosing fuel systemproblems).:��The return path for currentto flow back to its source.(Usually the negativebattery terminal.) It is alsothe reference point fromwhich voltagemeasurements are made.That is, it is the connectionplace for the minus (-) testlead from the voltmeter.

;�-)High-speed Electro-DriveFan relay. The ECAenergizes this relay when itdetermines extra enginecooling (more than thatprovided by EDF) isnecessary. Dependingupon the vehicle, the HEDFrelay will either speed-upthe same fan used by EDF,or it will turn on a secondfan mounted in front of theradiator.;�:,Heated Exhaust GasOxygen sensor. An EGOsensor (see EGOdefinition) having a built-inelectric heating element.The heater reduces sensorwarm-up time.;��>�3;>4A term for frequency –cycles per second.�&�Intake Air Control.�-�Ignition Diagnostic Monitor.A wire between the ECAand the switched side(Tach terminal) of theignition coil. The ECA usesthis circuit to check for thepresence of ignition pulses.��Electrical signals runninginto the ECA. Thesesignals come from sensors,switches or other electronicmodules. They give theECA information aboutvehicle operation.�� 9� ��3�9��4A single module containingseveral relays and someother circuitry. The ECAuses these relays forcontrol of functions such asfuel pump, air conditionerclutch, electric cooling fanand EEC-IV system power.

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�1�Idle Speed Control. Thisrefers to a small electricstepper motor mounted onthe throttle body andcontrolled by the ECA. (SeeStepper Motor definition.)The ISC motor moves aspindle back and forth.When the throttle isreleased during idle, it restson this spindle. The ECAcan control idle speed byadjusting this spindleposition. The ECAdetermines the desired idlespeed by looking at coolanttemperature, engine loadand RPM. The IdleTracking Switch (see ITSdefinition) is built-into thetip of the spindle. The ISCmotor also performsdashpot and anti-dieselingfunctions.�1�*./&Idle Speed Control By-PassAir valve. This is a solenoidtype actuator mounted onthe throttle body andcontrolled by the ECA witha duty cycle type signal.(See Duty Cycle definition.)It is used for idle speedcontrol. The valve operatesby regulating the amount ofincoming air bypassing theclosed throttle plate. Whenthe ECA increases controlsignal duty cycle, more airis bypassed through thevalve for faster idle speed.The ECA determines thedesired idle speed bylooking at coolanttemperature, engine loadand RPM. The ISC-BPAalso performs dashpot andanti-dieseling functions.�(1Idle Tracking Switch. Thisis a mechanical switchbuilt-into the tip of the IdleSpeed Control motorspindle. (See ISCdefinition.) The ECA usesthis switch to identifyclosed throttle condition.The switch is open whenthe throttle rests on it(closed throttle position).The MCU systems use asimilar acting ITS which ismounted on the carburetornear the throttle linkage.�81�Integrated Vehicle SpeedControl. The name given tothe speed control functionwhen it is built-into the ECAand not controlled by anoutside module.

?&/@9Keep Alive Power. A powerconnection running fromthe ECA directly to thevehicle battery. This poweris used energize the“learning memory” circuitsinside the ECA – evenwhen the ignition key is off.The memory storesadjustment information theECA uses to compensatefor aging sensors, and thelike. The information is lostwhen power isdisconnected, such aswhen the vehicle battery isremoved for service, butcan be “relearned” by theECA during normal engineoperation.?��5�The circuit which providespower to the engine controlsystem. Includes theignition key switch.?1Knock Sensor. The ECAuses this device to detectengine detonation(knocking). When sparkknock occurs, the sensorsends a pulsing signal. TheECA than retards sparkadvance until no detonationis sensed. The sensorcontains a piezoelectricelement and is threadedinto the engine block.Vibrating the elementgenerates the signal.Special construction makesthe element only sensitiveto the engine vibrationsassociated with knocking.2�-Light Emitting Diode. Asemiconductor devicewhich acts like a miniaturelight bulb. When a smallvoltage is applied, the LEDglows. LED’s may be red,orange or yellow or green.They are often used asindicators or in numericdisplays.2A1Lock-Up solenoid. Locatedin automatic transaxle. TheECA uses this solenoid tocontrol the lock-up clutch inthe torque converter. TheECAwill engage or release lock-up depending upon engineoperation.

�&)Mass Air Flow sensor. Thissensor measures theamount of air entering theengine and sends a voltagesignal to the ECA. Thesignal voltage increaseswhen the amount ofincoming air goes up. Thisgives the ECA informationrequired for control of fueldelivery, spark advanceand EGR flow.�&/Manifold Absolute Pressuresensor. This sensormeasures manifold vacuumand sends a frequencysignal to the ECA. Thisgives the ECA informationon engine load for controlof fuel delivery, sparkadvance and EGR flow.��&Message Center ControlAssembly. A dashboardmounted electronic displaygiving the driver tripcomputer and vehiclestatus information.Exchanges information withthe ECA by using the DataCommunications Link(DCL).��AMicroprocessor ControlUnit. A computerizedengine control module usedon many Ford vehiclesbetween 1980 and 1984.The MCU system consistsof a computerized controlmodule (MCU), sensorsand actuators. The systemcontrols fuel delivery andthermactor air flow. Laterversions of MCU alsocontrolled canister purge(see CANP definition),spark retard and idlespeed. The MCU systemwas eventually replaced byEEC-IV.�2/Manual Lever Positionsensor. Connected to gearshift lever. Sends a voltagesignal to the ECA indicatinglever position (P, R, N, D, 2or 1).��A type of operatingcondition, such as “idlemode” or “cruise mode.”

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0-1Neutral Drive Switch. Usedon vehicles with automatictransmissions. The ECAuses this switch todetermine when thetransmission is in or out ofgear. The ECA can adjustidle speed to compensatefor increased engineloading due to engagedtransmission.0:1Neutral Gear Switch. Usedon vehicles with manualtransmissions. The ECAuses this switch todetermine when thetransmission is in or out ofgear.0/1Neutral Pressure Switch.Located in automatictransaxle. The ECA usesthis switch to determinewhen the transaxle is in orout of gear.,�1Overdrive Cancel Switch.Used by vehicle operator.Signals ECA to preventshifting transmission intooverdrive (4th gear)regardless of operatingconditions.,��2Overdrive Cancel IndicatorLight. Located inpassenger compartment.Light turns on when vehicleoperator uses OverdriveCancel Switch to disable4th gear transmissionoperation.,��3��4A break in the continuity ofa circuit such that noelectrical current can flow.,��2��3,'24This is when a controlsystem performs an action(expecting a certain result),but has no way of verifyingif the desired results wereachieved. Example: TheECA pulses a fuel injectorexpecting a certain amountof fuel to be delivered. (TheECA assumes everythingin the fuel system isoperating as expected.) Inopen loop operation, theECA has no way ofchecking the actual amountof fuel delivered. Thus, afaulty injector or incorrectfuel pressure can changethe amount of fuel deliveredand the ECA would not

know it.,��Electrical signals sent fromthe ECA. These signalsmay activate relays orother actuators for controlpurposes around thevehicle. The signals canalso send information fromthe ECA to other electronicmodules, such as ignitionor trip computer./)�Pressure Feedback EGRsensor. The ECA uses thissensor to determine theamount EGR flow. The taskis involved. In this EGRsystem, a small openingseparates the exhaustmanifold from the EGRvalve input. All the gasesflowing through the EGRvalve must first passthrough this opening.Scientific principles allowthe ECA to calculate EGRflow providing it candetermine the pressure onboth sides of this opening(that is, both the EGR valveinput side and the manifoldside). The PFE sensormeasures the pressureseen at the EGR side. Thesensor sends a voltagesignal which increases aspressure is increased. Themanifold side pressure mustbe calculated by the ECAbased on RPM, exhaustsystem characteristics andother information. The ECAcan then finally calculateEGR flow. Note that withthis system, the PFE signalis NOT a direct measure ofEGR flow!/�/Profile Ignition Pick-Upsignal. It is a frequencytype, providing crankshaftposition and speedinformation. The ECA usesPIP as a reference tocreate properly timedignition system and fuelinjector signals. The PIPsignal comes from a sensormounted in the distributor(TFI-IV ignitions) or from aseparate crankshaftmounted sensor(Crankshaft PositionSensor) used ondistributorless ignitions.

/1/1Power Steering PressureSwitch. This tells the ECAwhen power steering isbeing used. The ECA canprevent stalling on a small,idling engine by watchingthis switch and increasingidle speed if power steeringis being used.B��C�(��Another name for Self-Test.(See Self-Test definition.)9� �A mechanical device forswitching high currentcircuits on and off. It iselectronically controlled bya low current circuit.Relays allows a low powerECA signal to control ahigh power device such asan electric cooling fan.9,�Read-Only Memory. This isinside the ECA. The ROMcontains permanentprogramming informationthe ECA needs to operatea specific vehicle model.Included are vehicleweight, engine andtransmission type, axleratio and other specifics.1&@Spark Advance Word.A signal used in someDistributorless IgnitionSystems. Sent from theECA to the DIS ignitionmodule to control sparkadvance timing. The SAWsignal is a series of voltagepulses. The width of thepulses is what tells the DISmodule what timing isdesired – wider pulsesmean less spark advance.An extra-wide pulse putsthe DIS modulein a “repetitive spark” modewhere several sparks aregenerated for everycylinder firing (used onsome vehicles at idle forlower emissions andsmoother performance).1��*(��Sometimes called “QuickTest”. A series of testsbuilt-into the ECA whichhelp locate vehicleproblems.The Code Scanner is usedto perform the tests and getthe results (in the form ofcode numbers).

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1��*(��The connector that theCode Scanner plugs intofor testing purposes. Theconnector is wired to theECA, and is located in theengine compartment. Testsare run and codes are readwith the Code Scannerconnected. Sometimes thisconnector is called VIP(Vehicle in Process).1��*(��31(�4A wire between the ECAand either the Self-Testconnector (MCU systems)or a separate connector(EEC-IV systems). Thewire is used to activate theSelf-Test procedures. TheCode Scanner connectsSTI to vehicle ground whenthe Test/Hold switch is inthe TEST position anddisconnects STI when theTest/Hold switch is in theHOLD position.1��*(��,��31(,4A wire between the ECAand the Self-Testconnector. Results ofvehicle diagnostic tests aresent along this circuit byusing a voltage pulsesignal. The signal switchesbetween “High” (+5 volts)and “Low” (close to zerovolts). The Code Scannerlight is OFF when STO is“High” and ON when STOis “Low”. Note: the lightmay be on or off when theignition key is off – dependsupon vehicle. The flashesrepresent code numbersused to locate problems.1��Device which give the ECAinformation. The ECA canonly work with electricalsignals. The job of thesensor is totake something the ECAneeds to know, such asengine temperature, andconvert it to an electricalsignal which the ECA canunderstand. The ECA usessensors to measure suchthings as throttle position,coolant temperature,engine speed, incoming air,etc.

1)��1�)�Sequential Fuel Injection orSequential Electronic FuelInjection. A fuel injectionsystem using one injectorfor each cylinder. Theinjectors are mounted in theintake manifold. Theinjectors are firedindividually in the samesequence as the spark plugfiring sequence.16��3��4A fault condition: anunwanted connection ofone electric circuit toanother causing a changein the normal current flowpath.1��A device to convert anelec- trical current tomechanical motion. Itconsists of a coil of wirewith a movable metal rod inthe center. When power isapplied to the coil, theresulting electromagnetismmoves the rod andperforms some mechanicalaction. The ECA often usessolenoids to switch vacuumlines on and off. This allowsthe ECA to control vacuumoperated devices such asan EGR valve. Fuelinjectors are another typeof solenoid.1� �C�9� ��1��Used on MCU systemshaving a knock sensor. TheMCU module energizes thissolenoid during engineknock conditions. Thesolenoid bleeds vacuumfrom the distributoradvance to retard sparktiming.1/,A(Spark Output signal fromthe ECA. Sent to TFI-IV orDIS ignition modules to firethe ignition coil(s) andcreate spark voltage.11�Shift Solenoid #1. Locatedin certain electronicallycontrolled transmissionsalong with Shift Solenoid#2. The ECA energizesthese solenoids (one orboth) to engage the desiredtransmission gear.

1��A special type of electricmotor with a shaft thatrotates in small “steps”instead of a continuousmotion. A certain sequenceof frequency type signals isrequired to step the motorshaft. A different signalsequence will step the shaftin the opposite direction.No signals keeps the shaftstill in position. A constantsignal drive willcontinuously rotate theshaft. The shaft is usuallyconnected to a threadedassembly which movesback and forth to controlthings such as throttleposition. The enginecomputer sends the correctsignals to the motor forcontrol.1(�Self-Test Input. (See Self-Test Input definition.)1(,Self-Test Output. (See Self-Test Output definition.)(&.Thermactor Air Bypasssolenoid. (Sometimescalled AM-1.) The ECAenergizes this solenoid toapply vacuum (and thusactivate) the TAB valve.Normally, this valve allowsincoming air to pass intothe rest of the system.When activated, the valvetakes the incoming air anddumps it back into theatmosphere. Refer toThermactor Air Systemdescription for more details.(&-Thermactor Air Divertersolenoid. (Sometimescalled AM-2.) The ECAenergizes this solenoid toapply vacuum (and thusactivate) the TAD valve.Normally, this valve directsincoming air to the catalyticconverter. When activated,the valve takes theincoming air and anddirects it to the exhaustmanifold. Refer toThermactor Air Systemdescription for more details.(-�Top Dead Center. When apiston is at its uppermostposition in the cylinder –maximum compression.

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()�*�8Thick Film Ignition system,version 4. An ignitionsystem consisting of adistributor, ignition coil andTFI-IV module. The ECAcontrols the spark advancetiming. A camshaft positionsensor in the distributorsends a reference signal(called PIP) to the ECA.The ECA sends a sparkadvance signal (calledSPOUT) to the TFI-IVmodule which fires thespark coil. The distributormechanically switches thespark voltage to the variousplugs in the usual manner.The ECA determinesoptimum spark timing fromsensor information – enginespeed and RPM, throttleposition, coolanttemperature, engine load,vehicle speed, gear leverposition and knock sensorcondition.(6�� &��1��An emission control systemconsisting of an air pump,air flow control valves (TAB& TAD) and a catalyticconverter. The converterremoves pollutants from theexhaust stream. An airpump brings outside air(when needed) and sendsit either to the exhaustmanifold (“upstream”) ordirectly into the converter(“downstream”). The ECAcontrols the air path forbest performance underdifferent engine operatingconditions. The air pumpalways runs when theengine runs. Usually theincoming air is directed tothe converter. Air is keptout during extended idling(prevent converteroverheat) or during verycold engine starting. Airgoes into the exhaustmanifold during normalengine warm-up. This helpsburn hot, unused fuelvapors in the exhauststream (reduces pollutants– speeds exhaust warm-up). The TAB and TADvalves may be separateunits, or combined into oneassembly.

(6��A resistor whose resistancechanges with temperature.Thermistors are used assensors for vehicle coolantand manifold airtemperature. Theresistance decreases astemperature goes up.(;1��' � ��(;1�!'�Transmission HydraulicSwitch. These are pressureswitches used in someautomatic transaxles. Theysend gear information tothe ECA as follows: THS 3/2 (only) signal means 2ndgear. Both THS 3/2 andTHS 4/3 signals means 3rdgear. THS 4/3 (only) signalmeans 4th gear.(?Throttle Kicker solenoid.The ECA uses this solenoidto apply vacuum (and thusactivate) the throttle kickeractuator. The actuatorincreases the amount ofidle position throttleopening by a fixed amount.TheECA activates TK whenoperating conditions requirefaster idle, such as whenthe A/C compressor is on,or during cold enginestart-up.(,(Transmission OilTemperature sensor. Thissensor is a thermistor – aresistor whose resistancedecreases with temp-erature. It lies within thetransmission housing incontact with the oil. TheECA uses this sensor tomonitor transmissionoperating temperature.(/Throttle Position sensor.This is a rotary typepotentiometer connected tothe throttle shaft. It has avoltage signal output whichincreases as the the throttleis opened. The ECA usesthis sensor to determine ifthe engine is in idle, partthrottle or wide-open-throttle operation. Then theECA can properly controlsystems such as idlespeed, spark advance, fueldelivery and emissioncontrols.

((1Transmission TemperatureSwitch. Sends atemperature status signalto the ECA.8 ��15��6A vacuum operatedelectrical switch. Theswitching action occurswhen applied vacuumreaches a certain level. Theswitches may either benormally closed or normallyopen. These are usedmainly in the MCU enginecontrol system. Theswitches send signals tothe MCU module.8&)Vane Air Flow sensor.This sensor is a rotary typepotentiometer connected toa moveable flap. It islocated inside the vanemeter assembly – ahousing between the aircleaner and throttle bodythrough which all incomingair passes. Flowing airpushes against the flap.The sensor sends a signalbased on the flap position.The voltage signalincreases when the flapmoves because ofincreased incoming airflow. The ECA determinesthe amount of incoming airwith this sensor. Thisinformation is used for forcontrol of fuel delivery,spark advance and EGRflow.8&(Vane Air Temperaturesensor. This sensor is athermistor – a resistorwhose resistancedecreases withtemperature. It is locatedinside the vane meterassembly – a housingbetween the air cleanerand throttle body throughwhich all incoming airpasses. The ECAmeasures incoming airtemperature with thissensor. This information isused for fuel deliverycalculations.

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8�9�Variable Control RelayModule. Containselectronic switches tocontrol power to A/C clutch,engine cooling fan, fuelpump, etc. ECA controlsmodule. A 2-wire DCLcircuit carries ECAinstruction signals to acomputer circuit insideVCRM. Power delivered byVCRM can be adjusted sothat, for example, enginefan can be slowly turned onor run at various speeds.891(EEC-IV systems): VariableReluctance Sensor. Asensor mounted on thecrankshaft which sends afrequency type signal to theECA. The ECA uses VRSto obtain information oncrankshaft position andspeed.(MCU systems):Vacuum RegulatorSolenoid. Used withfeedback carburetorshaving a vacuum controlledfuel metering system.(Feedback carburetors letthe engine computercontrol air/fuel ratios.) TheMCU module sends a dutycycle signal to VRS whichcontrols vacuum applied tothe fuel metering rod in thecarburetor. (See DutyCycle definition.) A low dutycycle signal reducescontrol vacuum for “rich”operation.A high duty cycle signalincreases control vacuumfor “lean” operation.811Vehicle Speed Sensor.This sensor, mounted inthe transmission, sends afrequency signal to theECA. The frequencyincreases as the vehiclemoves faster to give theECA vehicle speedinformation.88�Voltage Variable Chokeactuator. Used on feedbackcarburetors in MCUsystems. The MCU modulesends a duty cycle typesignal to this actuator inorder to control the amountof choke opening. (SeeDuty Cycle definition.)

@&�Wide-open-throttle Airconditioner Cut-off relay.Used by the ECA to turn offthe A/C clutch and thusreduce engine loading. Thisis desirable during heavyacceleration, engine crankingor engine overheatingconditions.@,(Wide Open Throttle. Thevehicle operating conditionbrought about when thethrottle is completely (ornearly so) open. The ECAtypically delivers extra fuel tothe engine at this time foracceleration purposes. TheECA uses the ThrottlePosition sensor to identify theWOT condition.@,(�8 ��15��6Wide Open ThrottleVacuum Switch. Used onMCU systems. The switchis closed when appliedvacuum is weak, and openwhen vacuum is strong. TheMCU module detects WOToperation when the weakmanifold vacuum presentduring WOT conditionscauses the vacuum switch toclose. The MCU moduleprovides extra fuel at thistime for accelerationpurposes.D��8 ��15��6�Used in someMicroprocessor Control Unit(MCU) systems. These threeswitches are used to detectlow, medium and highvacuum levels in the intakemanifold. They send electricalsignals to the MCU module.The MCU module can thencalculate throttle position andengine load.

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ONE (1) YEAR LIMITED WARRANTY

Actron Manufacturing Company (“Actron”) warrants to the original purchaser that this prod-uct will be free from defects in materials and workmanship for a period of one (1) year fromthe date of original purchase. Any unit that fails within this period will be replaced or repairedat Actron’s discretion without charge. If you need to return product, please follow the instruc-tions below. This warranty does not apply to damages (intentional or accidental), alterationsor improper or unreasonable use.

DISCLAIMER OF WARRANTYACTRON DISCLAIMS ALL EXPRESS WARRANTIES EXCEPT THOSE THAT APPEARABOVE. FURTHER, ACTRON DISCLAIMS ANY IMPLIED WARRANTY OF MERCHANT-ABILITY OF THE GOODS OR FITNESS OF THE GOODS FOR ANY PURPOSE. (TO THEEXTENT ALLOWED BY LAW, ANY IMPLIED WARRANTY OF MERCHANTABILITY OR OFFITNESS APPLICABLE TO ANY PRODUCT IS SUBJECT TO ALL THE TERMS AND CON-DITIONS OF THIS LIMITED WARRANTY. SOME STATES DO NOT ALLOW LIMITATIONSON HOW LONG AN IMPLIED WARRANTY LASTS, SO THIS LIMITATION MAY NOT APPLYTO A SPECIFIC BUYER.)

LIMITATION OF REMEDIESIN NO CASE SHALL ACTRON BE LIABLE FOR ANY SPECIAL, INCIDENTAL OR CONSE-QUENTIAL DAMAGES BASED UPON ANY LEGAL THEORY INCLUDING, BUT NOT LIM-ITED TO, DAMAGES FOR LOST PROFITS AND/OR INJURY TO PROPERTY. SOMESTATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF INCIDENTAL OR CON-SEQUENTIAL DAMAGES, SO THIS LIMITATION OR EXCLUSION MAY NOT APPLY TO ASPECIFIC BUYER. THIS WARRANTY GIVES YOU SPECIFIC LEGAL RIGHTS, AND YOUMAY ALSO HAVE OTHER RIGHTS WHICH VARY FROM STATE TO STATE.

TO USE YOUR WARRANTYIf you need to return the unit, please follow this procedure:1. Call Actron Tech Support at (800) 253-9880. Our Technical Service representatives aretrained to assist you.2. Proof of purchase is required for all warranty claims. Please retain your sales receipt.3. In the event that product needs to be returned, you will be given a Return MaterialAuthorization number.4. If possible, return the product in its original package with cables and accessories.5. Print the RMA number and your return address on the outside of the package and send tothe address provided by your Customer Service representative.6. You will be responsible for shipping charges in the event that your repair is not covered bywarranty.

OUT OF WARRANTY REPAIRIf you need product repair after your warranty has expired, please call Tech Support at (800)253-9880. You will be advised of the cost of repair and any freight charges.

All information, illustrations and specifications contained in this manual are based on the latest informationavailable from industry sources at the time of publication. No warranty (expressed or implied) can be madefor its accuracy or completeness, nor is any responsibility assumed by Actron or anyone connected with it forloss or damages suffered through reliance on any information contained in this manual or misuse ofaccompanying product. Actron reserves the right to make changes at any time to this manual oraccompanying product without obligation to notify any person or organization of such changes.

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Actron CP9015 Ford Code Scanner