1 BAR UPDATE 2007 Presented by LONG BEACH CITY COLLEGE ADVANCED TRANSPORTATION TECHNOLOGY CENTER Instructor - Pete Sparks/Cal Macy

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BAR UPDATE 2007

• Presented by

LONG BEACH CITY COLLEGEADVANCED

TRANSPORTATION TECHNOLOGY CENTER

Instructor - Pete Sparks/Cal Macy

The Bureau The Bureau of of

Automotive RepairAutomotive RepairPresents: Presents:

The 2007 The 2007

Smog Check Technician Smog Check Technician

Update CourseUpdate Course written by Wayne Brumettwritten by Wayne Brumett

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This course will provide an This course will provide an overviewoverview of the following: of the following:

Review of Computer Control Systems Review of Computer Control Systems Interaction and Advanced Fuel Trim Interaction and Advanced Fuel Trim DiagnosticsDiagnostics..

Networking and Controller Area Network Networking and Controller Area Network (CAN).(CAN).

OBD II - Mode 6 DiagnosticsOBD II - Mode 6 Diagnostics.. OBD II Evaporative Emission Control SystemsOBD II Evaporative Emission Control Systems. . Technical Service Bulletins and using Technical Service Bulletins and using

Manufacturers’ Internet sites.Manufacturers’ Internet sites. Computer Program Re-flashing.Computer Program Re-flashing. BAR Program Updates.BAR Program Updates.

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NOTICE TO TECHNICIANS:NOTICE TO TECHNICIANS:BAR update courses are designed to BAR update courses are designed to

provide Smog Check Technicians with provide Smog Check Technicians with Information on Program Changes and New Information on Program Changes and New

Technology that can Affect the Smog Check Technology that can Affect the Smog Check Program.Program.

This course is This course is notnot designed to teach you designed to teach you

in-depth information on a particular subject in-depth information on a particular subject area (e.g. Mode 6, EVAP Diagnostics, CAN, area (e.g. Mode 6, EVAP Diagnostics, CAN,

etc.). etc.).

As a professional automotive technician, As a professional automotive technician, you you are expected to are expected to educate yourselfeducate yourself (i.e. (i.e.

attend courses, read publications & training attend courses, read publications & training manuals, etc.) to complement your manuals, etc.) to complement your

understanding of this training course materialunderstanding of this training course material..

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To To passpass this course, you must this course, you must:• Read the Read the entireentire course textbook (prior to the course textbook (prior to the

course).course).• Read the two Motor Magazine articles (supplied Read the two Motor Magazine articles (supplied

by your school/instructor) on “CAN” and by your school/instructor) on “CAN” and evaporative (EVAP) system diagnosis.evaporative (EVAP) system diagnosis.

• Turn in for credit the Turn in for credit the 50 question50 question quiz in the quiz in the textbook on the first day of class.textbook on the first day of class.

• Successfully complete all the laboratory Successfully complete all the laboratory examinations.examinations.

• Attend all course hours.Attend all course hours.• Pass the written final examination (with a score Pass the written final examination (with a score

of 70% or better).of 70% or better).

Engine Control System Operating Strategy

- Overview -- Overview -The Input/Output

Relationship

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IntroductionIntroductionEngine Control System Operating Strategy is:Engine Control System Operating Strategy is:A programmed strategy in the Powertrain A programmed strategy in the Powertrain Control Module (PCM), that determines how Control Module (PCM), that determines how sensor input information will be calculated, sensor input information will be calculated, and what PCM output commands will be sent and what PCM output commands will be sent to the various actuators that control vehicle to the various actuators that control vehicle operation, based on those sensor inputs.operation, based on those sensor inputs.

As a technician, it is important for you to As a technician, it is important for you to understand the relationship between input understand the relationship between input values and output commands.values and output commands.

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IntroductionIntroductionIf the input signal to the PCM is If the input signal to the PCM is inaccurate, then the command from inaccurate, then the command from the PCM to the actuator(s) to control the PCM to the actuator(s) to control the vehicle will also be inaccurate.the vehicle will also be inaccurate.

Garbage In = Garbage OutGarbage In = Garbage Out

=

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SENSORSSENSORSAND AND

FUEL TRIM FUEL TRIM REVIEWREVIEW

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Review of Sensor/PCM Interaction

• The following information is the minimum needed for the engine controller to properly control the air/fuel mixture and ignition timing events:– Engine RPM– Engine Load (MAP / MAF)– Driver Demand (TPS)– Engine Coolant Temperature (ECT)– Barometric Pressure (BARO)– Intake Air Temperature (IAT)– Vehicle Speed (VSS)– Battery Voltage– Oxygen Sensor (O2 - used for fine tuning)

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Sensor/PCM Interaction - Review• Calculating basicbasic injector pulse width:

– Engine RPM– Engine Load (MAP / MAF)

• Sensor inputs used to modify basic pulse width:– Driver Demand (TPS) – Barometric Pressure (BARO)– Engine Coolant Temperature (ECT)– Intake Air Temperature (IAT)– Vehicle Speed (VSS)– Battery Voltage– Oxygen Sensor (used for fine tuning)

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Sensor/PCM Interaction - Review

• Injector pulse width is calculated based on sensor inputs, and fine tuned utilizing the oxygen sensor input(s).

• The computer compensates for variations in engine mechanical, electrical and sensor tolerances that develop over the vehicle life span, using Long Term Fuel Trim (LTFT) and Short Term Fuel Trim (STFT) values.

• LTFT corrections are made to move LTFT corrections are made to move STFT towardsSTFT towards the middle of the fuel the middle of the fuel correction scale.correction scale.

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Sensor/PCM Interaction - Review

The computer operates in either Open or Closed loop.• Open Loop:

– The oxygen sensor is ignored and signals from the other sensors, that are used to provide a basic pulse, are evaluated. The computer matches these conditions with values stored in memory (look-up tables) and issues commands to outputs devices (e.g. injector pulse width, timing advance, etc.).

• Closed Loop:– The computer now evaluates the oxygen sensor input

signal, and issues output commands to fine tune the fuel mixture.

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Fuel Trim OperationFuel Trim Operation

Subtracting Fuel

-40% -30% -20% -10% +10% +20% +30% +40%

Adding FuelAdding Fuel

Adaptive “Learned” Fuel Correction

= Long Term Fuel Trim (LTFT)= Long Term Fuel Trim (LTFT)

= Short Term Fuel Trim (STFT)= Short Term Fuel Trim (STFT)

Short Term and Long Term Fuel Trim Usually Operates

Within the 0 – 10%0 – 10% (+/-) Range, When There are No

Engine Performance Problems.

When the Engine Goes Rich, The STFT Subtracts Fuel. If it

Cannot Adust Enough, the LTFT Makes a (-) Adjustment

to Bring STFT Back into Operating Parameters

LTFT Subtracting Fuel

STFT Now Moves to MiddleLong Term Fuel Trim

0

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Fuel Trim DiagnosticsAn Excessive Increase in Fuel Trim May Be Due To:

Fuel starvation (restricted filter, low pump pressure, etc.)

Ignition system problems (i.e., misfires)

Vacuum leak

Mechanical problems

AIR System moving air up stream during closed loop

Upstream Exhaust leak

False Sensor Readings (MAF/MAP, O2, etc.)

An Excessive Decrease in Fuel Trim May Be Due To:

Excessive fuel Pressure

Restricted Air flow

Leaking Injectors

False Sensor Readings (MAF/MAP, O2, etc.)

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Sensor/PCM Interaction – Look Up Tables

So how does the PCM make the decision on how to adjust the fuel, ignition timing, and when to turn on/off the actuators?

The PCM is programmed from the factory with a series of mathematical algorithmic “look up tables.” These look up tables are similar to the multiplication tables you learned in grade school, only much more evolved.

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In this multiplication table, when you converge the outside numbers you want to multiply, you find the answer.

Example:

3 X 3 = 9

1 2 3 4 1 1 2 3 4 2 2 4 6 8 3 3 6 9 12 4 4 8 12 16 5 5 10 15 20


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Sensor/PCM Interaction – Load Cell

Load Cell:Load Cell: An embedded program in the Look Up Table that An embedded program in the Look Up Table that determines fuel delivery and timing from determines fuel delivery and timing from RPMRPM//load sensor inputsload sensor inputsUsing this multiplication table principle, lets build a simple load cell table, using just two inputs to determine the injector pulse width and ignition timing for a simple (theoretical) engine. As the throttle opens, more air enters the engine. The Mass Air Flow (MAF) sensor records the increase in air entering the engine. Based on the engine speed (RPM) and MAF readings (load), the look up table assigns preset commands for injector pulse width and ignition timing.

MAF = 7 Grams Per Second



750 RPM Inj. Pulse Width = 1.8 Timing = 8 degrees



Load Increase

CELL

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Of course, there are many sensor inputs that the PCM receives. The PCM, based on the inputs it receives, has to find a matching cell (as close as possible) in the ‘Look Up Table.” The PCM issues output commands (based on the selected cell) to operate the vehicle.

PCM Selects

Cell

PCM LOOK UP TABLESensor: Input Value

To PCM:ECT 0.5 volts

IAT 2.5 volts

MAP 1.0 volts

TPS 0.45 volts

RPM 750

HO2S .1-.9 volts

VSS 0 mph

B+ 14.0 volts

IAC 25%

Actuator: Actuator Output

Command:INJ. 3.01 ms

EVAP off

TCC off

EGR 0%

MIL off

Fan off

Loop closed

FP on

Timing 13 BTDC

PCM Receives Inputs

PCM Selects Closest Cell Match

PCM Sends Output PCM Sends Output Commands to ActuatorsCommands to Actuators

Based on the Cell Selected Based on the Cell Selected

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Have you ever heard of this situation Have you ever heard of this situation before?before?A technician diagnoses a bad throttle position sensor (shows 2 volts at idle) as the reason for high engine idle and engine performance/emission problems. He installs a new sensor, but the vehicle still runs poorly – why? Answer:Answer: The technician did not reset the

PCM’s adaptive strategy.

Sensor/PCM Interaction – Adaptive Strategy

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An “Adaptive Strategy” is programmed into a PCM’s “Keep Alive Memory” (KAM) to allow the computer to adapt to deteriorating component conditions (i.e., sensors, actuators, worn parts, etc.) and a driver’s driving habits. This programmed strategy allows the PCM to adapt (learn) to use abnormal inputs, and still allow the vehicle to operate within a normal vehicle performance range (within reason). The KAM will maintain this “learned” strategy as long as it is supplied battery voltage.


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In our scenario with the bad TPS, the technician, after completing the TPS repairs, did not clear the old TPS (adaptive strategy) information from the KAM (using the scan tool or

disconnecting the battery). The PCM was still using the stored (erroneous) information it learned (adapted) from the old defective part (2 volts at idle) to run the system. This is why the vehicle still performed poorly after the repair.


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Eventually, the PCM would have learned (adapted) to the new TPS input values

(after a series of drive cycles), and returned to normal operation. By not

resetting the PCM adaptive strategy, the customer would be upset when the

vehicle was returned to them as having been “repaired,” but still ran poorly.

Telling the customer to “just drive the car and it will get better” probably won’t set

too well with your customer.

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LTFT Adaptive Strategy

TIME BASE

The PCM has the ability to adjust to the driving habits of the driver. In this scenario, we

will see how the Long term Fuel Trim (LTFT) is adjusted

due to changes in the oxygen sensor and Short Term Fuel

Trim (STFT).1

Adaptive Strategy Program

Initially Assigns a +7 LTFT Value

2

O2 Sensor Reflects A Rich Condition

(high voltageSignal)

3 STFT Reacts to the High O2 Sensor

Voltage with a (-) 10 adjustment

4

LTFT Adjusts Down

To Bring STFT closer to “0”

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STFT is Now Within 5%

This Adaptive Cell has Now Been Corrected to This New LTFT Value

Speed Density Long Term Adaptive Cells

Let’s see this adaptive Let’s see this adaptive strategy in action. In the next strategy in action. In the next 5 scan tool screens, we will 5 scan tool screens, we will see the fuel trim cells for a see the fuel trim cells for a 2000 Dodge Intrepid with a 2000 Dodge Intrepid with a 3.5L engine, as viewed on a 3.5L engine, as viewed on a Chrysler DRB II scan tool.Chrysler DRB II scan tool.

Engine Speed isEngine Speed is795 RPM (Idle) 795 RPM (Idle) Trans in DriveTrans in Drive

Short TermShort TermFuel TrimFuel TrimIs at 0.0Is at 0.0

Open LoopOpen Loop

Injector Injector Pulse Width Pulse Width

is 2.8 mSis 2.8 mSLong Term Long Term Fuel Trim Fuel Trim is (–) 4.1 is (–) 4.1

(subtracting fuel)(subtracting fuel)

Based on inputs, the PCM selected Fuel Trim Cell #: C12. The cell is

commanding a negative (-) 4 % trim (adapted

strategy). On this vehicle, during openopen loop

operation, LTFT is used to establish injector pulse

width.Note that STFT is zero.


On this next screen, as the engine On this next screen, as the engine RPM increases above 1900, RPM increases above 1900,

LTFT moves into the upper row LTFT moves into the upper row of cells that have adapted to a of cells that have adapted to a previously learned condition.previously learned condition.

Note: Cells C4 & C5 are indicative Note: Cells C4 & C5 are indicative of the load and RPM that would of the load and RPM that would be used during an ASM test or be used during an ASM test or

Drive Cycle.Drive Cycle.

OO22 Reacts to engine conditions (high volts) Reacts to engine conditions (high volts)

STFT Responds to OSTFT Responds to O22 with – 6.2% with – 6.2%

With this load (MAP=11.6) and With this load (MAP=11.6) and RPM (1919)RPM (1919)

The PCM chose cell C5The PCM chose cell C5

If STFT goes too negative, If STFT goes too negative, LTFT will adopt a more LTFT will adopt a more

negative (-) strategy to subtract fuel for negative (-) strategy to subtract fuel for future use of this cellfuture use of this cell


In this next screen, we see the results of a major fuel trim correction. The

technician installed a new part, but did not reset the adaptive strategy. The

PCM is using a learned value from the bad part (+13%) in cell C8. Since the

problem has been corrected, the LTFT is now over fueling, and the STFT is making a major correction (-14%) to

adapt to the new situation.

LTFT Learned Value from Bad Part =

+ 12.7%

STFT Is trying desperately to

reduce fuel trim = - 14.1%

It will take a couple of drive cycles for the system to adapt to the newly installed part, but the

customer may complain about driveability problems.


In this next sceen, In this next sceen, the vehicle is the vehicle is

decelerating and all decelerating and all fuel trim has been cut fuel trim has been cut

to zeroto zero

With the throttle closed, the PCM

selects cell C15 to cut fuel delivery

(- 7%)

Note: Injector Pulse Width is

now zero

Resetting Long Term Fuel Trim Cells

In this next screen, we see that the In this next screen, we see that the technician has reset the adaptive fuel technician has reset the adaptive fuel

trim memory (via the scan tool). trim memory (via the scan tool). Note that all the fuel trim cells are now Note that all the fuel trim cells are now

set to zero. set to zero. With the system reset, the vehicle’s With the system reset, the vehicle’s driver may notice that the vehicle’s driver may notice that the vehicle’s

throttle response may now be sluggish, throttle response may now be sluggish, until the system has time to adapt.until the system has time to adapt.

Fuel Trim CellsReset to Zero

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- Review - As you can see, if sensor(s) input (e.g., MAF, TPS, As you can see, if sensor(s) input (e.g., MAF, TPS, IAT, ECT, etc.) is IAT, ECT, etc.) is incorrectincorrect, the PCM will still try to , the PCM will still try to match the (erroneous) inputs it receives to the match the (erroneous) inputs it receives to the closest matching cell. Due to the bad sensor closest matching cell. Due to the bad sensor input(s), the cell selected by the PCM will not be input(s), the cell selected by the PCM will not be appropriate appropriate for the actual operating conditions of for the actual operating conditions of the vehiclethe vehicle. The vehicle may now experience an . The vehicle may now experience an emission(s) failure/driveability problem. emission(s) failure/driveability problem.

Example:Example: If the wrong cell was selected by the If the wrong cell was selected by the PCM (e.g., using bad MAF info), that cell may not PCM (e.g., using bad MAF info), that cell may not allow EGR activation; thus the vehicle may fail for allow EGR activation; thus the vehicle may fail for NOx. If the correct cell were selected, the EGR NOx. If the correct cell were selected, the EGR would be activated, and the NOx problem would would be activated, and the NOx problem would not be present. not be present.

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- REMEMBER -- REMEMBER -• Garbage In = Garbage OutGarbage In = Garbage Out

=

- Review -

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NETWORK NETWORK AND AND

“CAN” “CAN” SYSTEMSSYSTEMS

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AUTOMOTIVE NETWORKSAUTOMOTIVE NETWORKSFor many years, as vehicle manufacturers added new features to their vehicles, they had to add more sensors, actuators, and wiring to accommodate these new features. These additions added more complexity to the vehicle, and required a larger and more expensive central computer.

For example, when electric cooling fans were first controlled by the OBD system, it was not uncommon for an engine to have three coolant temperature sensor/switches: one for the coolant temperature input to PCM, one for the electric cooling fan operation, and one for the coolant temperature warning light or gauge on the dash.

These extra sensors/switches were redundant, and added weight (less fuel economy) to the vehicle, and added more potential for system failure (shorts, opens, etc.).

To eliminate these problems, manufacturers changed to a network system.

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AUTOMOTIVE NETWORKSAUTOMOTIVE NETWORKS

When you use the internet, or use your ATM card at the bank or market, you are using a network system. This system shares information with other workstations (banks, internet providers, etc.) on a common carrier system (e.g. telephone or internet system).

A Local Area Network (LAN) is a network that is contained to one local area, like your home, shop, or car. Car manufacturers have been using LAN systems on cars for years.

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AUTOMOTIVE NETWORKSAUTOMOTIVE NETWORKS

The advantages to having a LAN system are:The advantages to having a LAN system are:• Eliminates hard wiring of sensors/actuators to every

component (e.g. PCM, warning lights, fans, etc.), which results in lower production costs.

• Eliminates redundant components and wiring, which reduces vehicle weight (better fuel economy).

• Reduces potential system failures (shorts, opens, etc.), since there is less wiring.

• Information transfer is faster between component systems.

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CONTROLLER AREA NETWORK CONTROLLER AREA NETWORK (CAN)(CAN)

NO, we are not talking about this kind of Can!

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Most vehicle manufacturers are moving to a network system called “Controller Area Network” (CAN). This system will be required on all light duty vehicles sold in California by model year (MY) 2008.The advantage of this system is that all vehicles will have a standardized communication protocol, so your scan tool will be able to communicate with this high speed network system.

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CONTROLLER AREA NETWORKCONTROLLER AREA NETWORKSo how does this “CAN” So how does this “CAN” system work?system work?In general, the system employs a “data bus” (bus) wire to carry individual information packets (sensor outputs, computer commands, etc.) throughout the network system.Think of this bus as a freewayfreeway, with on-ramps and off-ramps to cities (i.e., modules) that can exchange information. The cars are like information packets traveling the bus.

Trans Module

HVAC Module

Dash Module

Information Packet

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CONTROLLER AREA NETWORKCONTROLLER AREA NETWORK

The CAN bus wire is usually a two wire configuration, with a positive (+) and negative (-) wire. Each wire is capable of transmitting information.

The wire is twisted to reduce stray (induced voltage) signals coming into the bus wire from adjacent high voltage sources (e.g., secondary ignition wires, coils, etc.).

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Connected to the bus are modules (most are programmable). These modules are like small computers.

Most modules can receive information packets off of the bus (like sensor/actuator information –off-ramps), and also send information packets (like on-ramps) to travel on the bus, to be used by other modules.

Using these modules eliminates the need to have large and expensive centralized computers.

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CONTROLLER AREA NETWORKCONTROLLER AREA NETWORKModules can be placed at various locations on the vehicle, in close proximity to sensors, actuators, and components they serve. Since most modules are programmable, and use a standardized communication protocol, they can be programmed to accommodate any new sensor, actuator, or component the manufacturer chooses to add during updates - without extensive re-wiring.

Bus Wire

Module

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CONTROLLER AREA NETWORKCONTROLLER AREA NETWORKAt this point, you might be asking yourself:

““So how does all that information get transferred on a So how does all that information get transferred on a single (two wire) network?single (two wire) network?

Isn’t there going to be a traffic jam of information going Isn’t there going to be a traffic jam of information going to and from the modules?” to and from the modules?”

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Each module is programmed to emit it’s data, using an electronic code. This coded data packet is given a priority, based on how important it is to the operation of the vehicle.

The Engine Temp

Sensor Sends a

HOT ENGINE Signal to

the Module

The Module Converts the Analog Temp Signal into a

Digital Information Packet, to be Sent Out on the Bus. The

Information Packet is assigned a Priority Code. In this Case, it is

Given a High Priority Code

OK kid, You have got your priority code,

now get on that bus and tell everyone

who wants to know, that we have a big problem with the

engine!

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CONTROLLER AREA NETWORKCONTROLLER AREA NETWORKEach module, commonly referred to as a “Slave” module, is connected to a “Master” module. The Master module sorts the information packets on the bus, and decides the order in which an information packet should be sent (via priority) on the bus (like a traffic officer).Some of the Slave modules are in a sleep mode, and the Master module has to wake them up. The reason they are in the sleep mode is to reduce parasitic battery drain when the vehicle is not in use.

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The Master module will wake up a Slave module for the following reasons:

Another module is requesting information that the sleeping module can provide (e.g., sensor/actuator information).

Another module is sending information that the sleeping module needs (e.g., actuator commands, etc.).

The Master module determined that more computing ability is needed to operate the vehicle, so it uses the computing resources of the sleeping module to assist in carrying out difficult computing functions (an additional computer resource).

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There are three classes of CAN. The classes are defined by the Society of Automotive Engineers (SAE) based on data speed of the bus; measured in kilobits per second (kbpskbps):

CAN “A” – Has very slow data transference speed, at about 10 kbps. This class was used on early vehicle systems, but is seldom used today.

CAN “B” – Has medium data transference speed at about 83 - 125 kbps. This class is used for vehicle systems that don’t require exceptional data transference speed (e.g., body control module, HVAC module, etc.).

CAN “C” – Has high data transference speed, at about 500 - 1000 kbps. This class is used primarily on powertrain and chassis systems that require high data speed (e.g., electronically operated: throttle, steering, brakes, etc.). Usually, this system only has three modules (e.g., PCM, TCM, ABS).

0

200

400

600

800

1000

CAN "A"

CAN "B"

CAN "C"

CAN Bus Speed (in kbps)

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Most vehicles today employ the use of both CAN “B” and “C” bus systems to operate the vehicle.

To allow these two bus systems, of vastly different data rate speeds, to share information with each other, the CAN system employs a “Gateway” module.

The Gateway acts as an interface between the different buses (like an interpreter), which allows them to share information. Usually, the Master module and the Gateway module are incorporated into one unit.

GATEWAY/MASTERMODULE

SCAN TOOLINTERFACE

MODULE

PCM

TCM

ABS/ACTIVE

SUSPENSION

INSTRUMENTCLUSTER

DOOR/WINDOW

OPERATIONS

HVACCLIMATECONTROL

BODYCONTROL

CRUISECONTROL

STEERINGCOLUMN/IGNITION

CAN “B” BUS

CAN “C” BUS

CAN “B” CAN “C”

GATEWAY

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System Failure:System Failure:

If one of the two wires on the CAN “B”CAN “B” bus has a short/open, then the following maymay happen:

The system will still operate, but may not function as designed. The system may be slow in operation.

Depending on where the short/open is located, some part of the system may not operate at all.

If a sensor input from a defective section cannot get a signal to a good module needing that sensor input, then that good module may not operate as designed (e.g., bad module attached to speed sensor may cause problems with PCM outputs).

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System Failure (con’t):System Failure (con’t):

In a severe CAN “B”CAN “B” bus wire failure (both wires open/grounded), multiple system failures can occur.

Improper dashboard warning light operations may occur.

MIL will be illuminated.

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System Failure (con’t):System Failure (con’t):

The CAN “C”CAN “C” bus may be faster, but it is not as fault tolerant as the CAN “B”CAN “B” bus.

Any shorts or opens maymay make the system inoperable, and cause false dash readouts (e.g. engine temperature).

I GUESS THE BUS STOPS HERE!

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CONTROLLER AREA NETWORKCONTROLLER AREA NETWORKSystem Failure (con’t):System Failure (con’t):The Gateway/Master module is constantly polling all the modules to check their readiness status, and their ability to transmit/receive data.

If a module is operating incorrectly, the Gateway/Master module will advise all the other modules that this module is inoperative, and to ignore it. The Gateway/Master module will continue to poll that problem module to see if a correction was made while the vehicle is in operation. If the module returns to operational status, the Gateway/Master module will inform all the other modules that this module is now operational, and to accept that module’s information.

If a module continues to be faulty, or the bus wire is faulty, a “U” Code“U” Code (DTC) will be generated.

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NOTE:NOTE: For you to diagnose/repair a CAN vehicle, you need to have access to the appropriate diagnostic manuals, TSBs, and have a CAN compatible scan tool. Most scan tool manufacturers already have CAN compatible tools and upgrades available.

A Smog Check Test and Repair station must have a CAN compatible scan tool to inspect CAN vehicles.

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CANCAN CASE STUDY: CASE STUDY:To illustrate how the CAN system is a fully integrated/interactive system, here are two true stories:

One evening, a fleet maintenance technician changed a defective license plate bulb on a fully functional 2005 Ford truck. The next morning the truck would not start! What happened?It appears that the bulb he replaced was of a higher amperage rating than the original bulb. The multiplex system sensed the higher amperage draw during a system self test at start up, and shut down the fuel pump relay. The PCM did this so the bus system and components would not be damaged by the bulb’s high current draw while the vehicle was operational. This was not an easy one to figure out, since the repair This was not an easy one to figure out, since the repair technician was not aware that the bulb had been replaced the technician was not aware that the bulb had been replaced the night before!night before!

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CANCAN CASE STUDY (con’t): CASE STUDY (con’t):

CAN Arachnophobia: A 2004 Ford comes into the shop with the following complaints: The vehicle periodically slows down to a maximum speed of 25-35 mph for no reason (even at full throttle); and by the way, the “door ajar” light comes on occasionally, even though all doors are closed tight. What’s the problem?

After a lot of head scratching, it was found that baby spiders had made a nest in the rear door switch, causing an intermittent poor circuit problem (door ajar). The CAN system thought the door was open going down the highway; so to protect the passenger from an unscheduled bailout at fatal speeds, the PCM limited the vehicle to 35 mph. Who would of seen this one coming? Keep the door closed during an ASM test!

OBD II OBD II EVAPORATIVE EVAPORATIVE

EMISSION EMISSION CONTROL CONTROL SYSTEMSSYSTEMS

OBD II OBD II EVAPORATIVE EVAPORATIVE

VideoVideoLow Pressure Evap Low Pressure Evap

TestingTestingCA Dep. Consumer Affairs- Bur. Automotive Repair - Low Pressure Fuel Evaporative Testing.url

http://smogcheck.ca.gov/Consumer/lpfetvideo.htm

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Common Terms

• Back Door Back Door Canister Closed Valve or Canister Closed Valve or Vent Solenoid ValveVent Solenoid Valve

• Charcoal Canister Charcoal Canister Evaporative Emission Evaporative Emission CanisterCanister

• Front Door Front Door EVAP VSV, Purge VSV, EVAP VSV, Purge VSV, Purge SolenoidPurge Solenoid

• FTPSFTPS Fuel Tank Pressure Fuel Tank Pressure SensorSensor

Types of Evaporative Types of Evaporative Emission SystemsEmission Systems

• Pre-OBD II: These systems could not perform leak checks, but some systems could identify canister purge operation.

• OBD II: A variety of systems are in use today: Non-EnhancedNon-Enhanced systems can only detect purge flow.

These systems do not include a readiness monitor. EnhancedEnhanced systems can: detect a leak using vacuum

or pressure, monitor fuel vapor purge flow, and they include a readiness monitor. (Some systems test when the key is turned off)

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Identifying EVAP Systems

• The first source of information is the under-the-hood emission decal.– Keep in mind that the decal onlyonly shows

components located in the engine compartment.

• The second source is the component locator manual for the vehicle in question.

• The third source is the actual wiring diagram for the vehicle in question.

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OBD II OBD II Non-EnhancedNon-Enhanced

Evaporative Evaporative Control System Control System

OperationOperation

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Early OBD II Evaporative Early OBD II Evaporative Emission Control SystemsEmission Control Systems

• Early OBD II systems did Early OBD II systems did notnot require Enhanced require Enhanced Evaporative Emission Controls.Evaporative Emission Controls.– Non-Enhanced systems were in limited use from 1996 Non-Enhanced systems were in limited use from 1996

to 2000.to 2000.– This means the system This means the system could not detect a leakcould not detect a leak; a ; a

loose or missing gas cap would not be identified by loose or missing gas cap would not be identified by this systemthis system

– It can only detect vapor flow or purge vacuum by It can only detect vapor flow or purge vacuum by using a switch or fuel trim.using a switch or fuel trim.

• This system can be identified quickly by using the This system can be identified quickly by using the underhood vacuum diagram. The diagram will indicate underhood vacuum diagram. The diagram will indicate just a purge solenoid with a vapor or purge switch (no just a purge solenoid with a vapor or purge switch (no vent solenoid valve).vent solenoid valve).

63

A typical non-enhancednon-enhanced evaporative control system contains the following components:

1. Evaporative emission pressure control valve.2. Vented canister.3. Diagnostic switch.4. Purge solenoid.

4.

1.

2.

3.

64

PCM

EVAP Diagnostic Switch

Front door closedFront door openedopened

When the PCM energizes the system to purge the fuel vapors, it sends a duty cycle to the purge solenoid (front door openopen). At a purge solenoid duty cycle of approximately 25%, the normally closed vacuum switch contacts should open due to vacuumvacuum in the purge line. The PCM interprets this vacuum switch opening (i.e., 0.0 volts on the meter) as purge system flow.

Chassis Ground (-)

00.00V

When the purge valve is not activated by the PCM,

(front door closedclosed) there is no vacuum in the line to the EVAP canister. The

EVAP. Diagnostic (vacuum) Switch is closed.

HC

HC

Purge Solenoid(front door)

ON

Switch Closed

SwitchSwitch

OpenOpen

NonNon-Enhanced System

0 Volts = PurgeEngine

65

OBD II ENHANCED ENHANCED

EVAPORATIVE CONTROL SYSTEM

OPERATION

Overview of Enhanced Evaporative Overview of Enhanced Evaporative Emission Leak DetectionEmission Leak Detection

•Beginning in 1998, Enhanced EVAP systems appeared, that were capable of detecting a leak as small as .040 of an inch (.040”).•By 2000, all vehicles were required to phase in an Enhanced EVAP system capable of

detecting a leak as small as .020”.•Both systems include an EVAP Readiness

Monitor that runs once per “Trip” when the Enable Criteria is met.

•Some manufacturers included a diagnostic “Service Bay” test in their scan tools to assist with the verification of a repair.

67

Enhanced Evaporative Emission Enhanced Evaporative Emission Leak Detection SystemsLeak Detection Systems

Vacuum Decay: Uses engine vacuum to create a vacuum in the fuel tank, canister, and lines to identify leaks.

Fuel Tank Pressure/Canister Vacuum: Using engine vacuum, this system can isolate the fuel tank from the Charcoal Canister (via a solenoid valve) to pinpoint a leak.

Leak Detection Pump: Uses flow from a pump to pressurize the system to check for leaks.

Engine Off Natural Vacuum Leak: Uses the principle of gas/fluid expansion/contraction in a closed container. As temperature changes, the resultant increase/decrease in pressure or vacuum will identify if leaks are present.

68

PCM

Front Door Closed

Back Door Open

FTPE I I I FE I I I FE I I I FE I I I FE I I I F

The main difference between The main difference between the the non-enhancednon-enhanced system and system and the the enhancedenhanced system, is that system, is that the the enhancedenhanced system has the system has the

ability to check itself for ability to check itself for system leakage (in addition to system leakage (in addition to vapor purge operation). The vapor purge operation). The

leakage test is part of the OBD leakage test is part of the OBD II monitoring system.II monitoring system.

The enhanced system has the same components as the non-enhanced system, but also has:

A Canister Vent Solenoid (back door - usually open)

A Fuel Tank Pressure Sensor

Vent Solenoid(back door)Fuel Tank Pressure Sensor

When the system is at rest (no purging or monitor testing)

the vapors are stored in the

canister.

69

PCMFront door openedopened

FTPE I I I F

When the purge valve is activated, the

canister is purged of fuel vapors.

70

PCMFront Door

OpensOpens

Fuel Tank Pressure Sensor

FTP

When the EVAP EVAP Monitor runsMonitor runs, and the

system tests for leaks, it first opens the front

door to create a vacuum in the system. Back Door

OpenOpen

71

PCMFront Door OpenOpen

Back Door ClosedClosedFuel Tank Pressure Sensor

010203040506

Front Door ClosedClosed

FTP

Back Door OpenedOpened

As the vacuum is applied to the system,

the back door is closed. This seals the system so a vacuum is created from the gas

cap to the purge solenoid.

Once a specified vacuum reading is obtained, the PCM

closes the front door.

The PCM now monitors the Fuel

Tank Pressure Sensor for

vacuum loss (decay) over a period of time.

VACUUM

After the specified test time has passed, the back door is

opened, and the system returns to normal. If there was too much vacuum loss during the test period, the PCM will assume there is a leak and

set a DTC.

Vacuum Decay System

VACUUM

72

PCM

What does the PCM have to see before it can run the EVAP Monitor

and test the system?

First, ALL the criteria needsto be met before the PCM can run the EVAP monitor.

What does that mean?

Requirements to Run the EVAP Monitor:

•MIL must be off.•Elevation must be lower than 8000 feet.•At start-up, IAT & ECT are between 45°F & 85°F.•IAT is not more than 2°F greater than ECT.•ECT is not more than 12° greater than IAT.•Fuel tank level is between 26 & 74 % (approximately, depending on mfr. specifications).•The TPS is between 9 & 35% throttle angle.

A CLOSER A CLOSER LOOK AT LOOK AT

COMPONENT COMPONENT PARTSPARTS

Purge Solenoid (Front Door)1) A Normally Closed solenoid

that receives battery volts and is duty cycled on/off (to ground) by the PCM.

2) On a vacuum decay system, it is used to create a vacuum in the tank for the purpose of checking the system for leaks.

3) Purging occurs during closed loop. The PCM will adjust fuel delivery while the system is purging.

Vent Solenoid (Back Door)1) It is a Normally Open solenoid

that receives battery voltage. To close the valve, the PCM must ground the circuit.

2) It is open to atmospheric pressure when the solenoid is not grounded by the PCM.

3) The only time it is commanded closed (grounded by PCM), is when the EVAP Monitor is running.

4) Some systems use a fresh air filter for inlet air to the canister.

5) This system can suck in dirt, water, and cob webs, and can result in a failed solenoid.

Fresh Air Inlet

76

Fuel Tank Pressure (FTPS) Sensor

• The EVAP System Pressure Sensor is the primary sensor that identifies vacuum/pressure decay during the EVAP Monitor test.

• This sensor is extremely sensitive, and can accurately measure to less less than 0.01 PSI!than 0.01 PSI! The sensor can measures bothboth positive pressure and negative pressure (vacuum).

SensorSensor

77

Service PortService Port• Service Ports are provided for Service Ports are provided for

testing of the EVAP system.testing of the EVAP system.• They are usually located They are usually located

between the canister and purge between the canister and purge solenoid. solenoid.

• Although Although notnot required, some required, some OEMs provided an EVAP OEMs provided an EVAP service port on their vehicles.service port on their vehicles.

• The service port systems come The service port systems come in different hoses and Schrader in different hoses and Schrader valve sizes. Additionally, they valve sizes. Additionally, they can be part of a molded hose. can be part of a molded hose.

Service Port

Service Port Cap

Safety Notice

Note: The Schradervalve is a left handthread (turn clock-wise to remove).

If you remove the valve, be sure not to lose it! If you do lose it, the Service Port Tee can be bought fromthe Dealer.

79

Evaporative Emission DiagnosticsEvaporative Emission Diagnostics

To successfully repair an EVAP system failure, you should:

1. Understand how the system operates.

2. Understand the trouble code. Is it an electrical or mechanical fault? Not all EVAP codes are system leakage codes.

3. If possible, confirm or duplicate the problem. This may mean running the EVAP monitor or Service Bay test.

4. Properly prepare the system for leak testing.

5. Use an approved (by the testing equipment mfr.) leak detection/smoke machine that is designated by the mfr. for use to detect EVAP leaks.

6. Confirm the repair by running a monitor.

80

Diagnostic Plan for EVAP LeaksDiagnostic Plan for EVAP Leaks

MIL is “ON”

Verify an EVAP DTC is present &

query the freeze frame data

Search for relatedTSBs and referto the DTC’sTrouble Tree

Locate the leak with your BAR 97 EIS (manual mode);

or With a smoke machine

and awhite light

Repair the systemand retest

Isolate the leak bysealing the EVAP

system

Clear DTC(s) andif possible run the

Monitor to confirm repairs

Confirm the leakexists by using an

EVAP tester

Pinpoint the leakw/UV dye, an

ultraviolet light, & yellow goggles

or

81

EVAP Technical Service BulletinsEVAP Technical Service Bulletins

Before you get too far down the wrong

diagnostic trail, make sure you check for

manufacturer Technical Service Bulletins (TSBs) to see if they are related

to your EVAP failure.

Courtesy of Toyota Motor Company

82

Evaporative Emission DiagnosticsEvaporative Emission Diagnostics

Getting Started:Getting Started: Look for loosely fitting hoses or clamps, cracked hoses,

or any signs the system could have been damaged in an accident.

Verify all electrical connections: Purge Solenoid Bypass Valve Vent Solenoid or Canister Closed Valve Fuel Tank Pressure Sensor

Verify the operation of the Purge and Vent solenoids by activating them using bi-directional testing, if the vehicle is so equipped. Listen and feel for correct operation as each solenoid is turned ON/OFF. Repeat this test multiple times to exercise the solenoid(s).

83

84

EVAP Leak Detection EquipmentA typical EVAP Leak Detection station should consist of:

1. An appropriate EVAP Leak

Detection/Smoke machine2. Nitrogen bottle and

regulator3. Cart

Note:The system displayed is not necessarily representative of future BAR required inspection equipment.

1

2

3

85

EVAP Leak Detection MachineEVAP Leak Detection Machine

• An appropriate EVAP testing/smoke machine consists of:1. Flow Meter2. Calibration

buttons3. Pressure Test4. Smoke Generator5. Oil Level Dipstick

1

2

3 4

5

86

Connecting to the Service PortConnecting to the Service Port

To EVAP Tester

Remove Schrader Valve When Smoke Testing

87

What do you do if there is NO EVAP service port ?

Testing can be performed without a Service Port.

88

Purge Valve(Front Door)

Vapor Management Valve

To intake manifold

To Charcoal Canister / Fuel TankTo Charcoal Canister / Fuel Tank

Remove the hose from the Purge Solenoid to the Canister and apply pressure into the hose using an appropriate EVAP tester.

To Tester

89

Flow Meter CalibrationFlow Meter Calibration

It is important that you calibrate the flow meter

beforebefore performing any leak testing.

Calibrated Leakage Port (.020”)

Calibrated Leakage Port (.040”)

90

•BEFOREBEFORE you beginyou begin EVAP pressure EVAP pressure testingtesting, you mustmust calibrate the flow meter scale on the EVAP tester to the maximum leakage that is acceptable for the year of the vehicle being tested.

•Select the correct calibration orifice (.020” or .040”) on the tester panel (in this case we selected the .040”).

•When you start the calibration test, the red ball will rise in the tube to the calibrated level of leakage.

•Slide the red arrow (left of tube) to match the red ball level. You are now calibrated, and can continue with the pressure test.

Sliding Adjustment

Flow Meter CalibrationFlow Meter Calibration

91

Closing the Vent Solenoid (Back Door)

Prior to pressure testing the EVAP system, you must seal the system by closing the vent solenoid valve. To close the valve you can:

• Use Mode 8 of a Generic scan tool.

• Use Functional or Output Tests found on the OEM side of an aftermarket scan tool.

92

Generic OBD II (MODE 8) EVAP System Test

When you activate this test, the vent solenoid (back door) should close.

On your scan tool, select the EVAP Leak Test mode

You may now pressurize the EVAP

system

93

Using the OEM Functional or Output EVAP Tests

Here is an example of how to close the back door (vent

solenoid) using an OEM scan tool

94

First of all, it’s NOT a fault of the scan tool.

Some systems are not designed

to do this task!

SCAN TOOL CAN’T CLOSE THE BACK DOOR?SCAN TOOL CAN’T CLOSE THE BACK DOOR?

95

Put to known good ground

KOEO

O FF

V

V

m V A

m AA

Hz

A COM

10A M AXFUS E D

2A M AXFUS E D

HzV/ m A

AUTO ACDC

12.43v00.00v

Manually Closing the Vent (Back Door) Solenoid

VentValve

Vent Valve (B

+) Wires

With the vent solenoid wire

harness removed, find the power feed (B+) wire to the vent

solenoid

96

O FF

V

V

m V A

m AA

Hz

A COM

10A M AXFUS E D

2A M AXFUS E D

HzV/ m A

AUTO ACDC

00.00mA00.00v

To Manually Close the Vent Valve:

Once you have identified the hot (B+) wire,

reconnect the wire harness to the vent

solenoid Now, reconfigure

your DVOM to read milliamps

Wire Harness Vent

Valve

97

Battery of vehicle being

tested.

Note: To avoid fuel vapor ignition, attach the meter (-) ground lead to a known good ground

AWAY FROM THE VENT VALVEAWAY FROM THE VENT VALVE

O FF

V

V

m V A

m AA

Hz

A COM

10A M AXFUS E D

2A M AXFUS E D

HzV/ m A

AUTO ACDC

450mA

- +

To Manually Close the Vent Valve:

+-

Back probe the harness “ground”

wire with the positive (+)meter lead

Then connect the negative (-) meter lead

to a good ground.

With KOEO, you should now see a reading on your meter (mA), and the vent valve

should be closed; you may

continue with your pressure

test.

98

Manually Closing the Vent (Back Door) Solenoid

The system can be manually closed by clamping the fresh

hose before or after the vent

solenoid.

Vent Valve Hose to Air Filter – Clamp Here

Vent Solenoid

Use

Hose Pliers

to Clamp

EVAP Hoses

99

Pressure Testing for a LeakPressure Testing for a Leak

• During the leak test of the EVAP system, the higher the ball riseshigher the ball rises, the larger the leak.

• If the ball rises above the red arrow, the system failed the leak test. Is this a failed test? (read on)

100

Pressure Testing for a LeakPressure Testing for a Leak• The picture shows the red

test ball below the maximum leakage specification of .040”.

• This vehicle's monitor system set a small leak code (P0442) because the system must code by the time the leak is as large as .040”. Different mfrs. have their own tolerance levels for setting a leak DTC – most set a code sooner than the maximum fail point (e.g. .040”).

101

Leak Detection Using a Smoke Machine

With the Vent Solenoid (back door) closed and the gas cap off, apply smoke (via the test port) until it comes out the filler neck, then reinstall the cap.

If smoke does not come out the fuel filler neck, the fuel level might be too high, or there could be a solenoid in the middle of the system, or you forgot to remove the test port Schrader valve.

102

• While applying smoke, use a white (e.g., halogen) light to locate the leak.

• If the leak cannot be located, use a UV light and yellow goggles to pinpoint the leakage. The dye in the oil will show up as a blueblue/green green colored residue.

Leak Detection Using a Smoke Machine

Leakage Residue on Clamp

103

Retest after Repairing the System

After repairing the problem,apply pressure for a minute or two; this should allowenough time for the system to fill completely. If your repairs were successful, the ball will be at the bottom of the flow meter during the test.

EVAP System SafetyEVAP System Safety•Do not, Do not, under any circumstancesunder any circumstances, pressurize , pressurize

the system with an air hose. This action can the system with an air hose. This action can cause:cause:

1.1. Damage to many components in the Damage to many components in the EVAP system.EVAP system.

2.2. A vapor hazard to yourself and fellow A vapor hazard to yourself and fellow technicians.technicians.

•Testing of the EVAP systems can result in Testing of the EVAP systems can result in the escape of explosive fuel vapor. the escape of explosive fuel vapor. Do not Do not smoke while testing the EVAP systemsmoke while testing the EVAP system, and , and be sure the vehicle is in a well ventilated areabe sure the vehicle is in a well ventilated area.

•Always use Always use nitrogennitrogen gas to test an EVAP gas to test an EVAP system.system.

Plus EVAP Testing= BYE BYE TECHNICIAN

Technician Smoking

MODE 6MODE 6

DIAGNOSTICSDIAGNOSTICS

106

MODE 6 DiagnosticsMODE 6 DiagnosticsYou might be asking yourself, “So what is this You might be asking yourself, “So what is this Mode 6, and how can it help me diagnose Mode 6, and how can it help me diagnose vehicle emission problems?”vehicle emission problems?”

– Mode 6 tests can assist you to confirm the Mode 6 tests can assist you to confirm the success of repairs you performed that are related success of repairs you performed that are related to a non-continuous monitor.to a non-continuous monitor.

– Mode 6 test values (and pending DTCs) are Mode 6 test values (and pending DTCs) are available to the technician on the available to the technician on the firstfirst trip of a two trip of a two trip monitor.trip monitor.

– Mode 6 test results can give you an indication if a Mode 6 test results can give you an indication if a monitored system (component) is close to failing monitored system (component) is close to failing a monitor test.a monitor test.

MODE 6 DiagnosticsMODE 6 Diagnostics

As was noted in your textbook, As was noted in your textbook, Mode 6 has been around as long as Mode 6 has been around as long as OBD II has been around. Mode 6 OBD II has been around. Mode 6 was one of the original criteria that was one of the original criteria that vehicle manufacturers were vehicle manufacturers were required to include in their on-board required to include in their on-board computer systems.computer systems.

Mode 1: Data Stream

Mode 2: Freeze-Frame Data

Mode 3: Diagnostic Trouble Codes (DTCs)

Mode 4: Clear Codes & Freeze Frame Data

Mode 5: Oxygen Sensor Monitor

Mode 6: Non-Continuous Monitors

Mode 7: Continuous Monitors

Mode 8: Bi-Directional Communications (Onboard Tests)

Mode 9: Vehicle VIN, PCM Calibration Etc.

108


Simply put, Mode 6 Simply put, Mode 6 displays the test displays the test results of results of non-non-continuous continuous monitorsmonitors..

Unfortunately, the Unfortunately, the manufacturers were manufacturers were not required to give not required to give this test data in a this test data in a format that everyone format that everyone could understand.could understand.


To display the non-continuous monitor test results, somesome manufacturers (engineers) used the Hexadecimal system (dollar sign - $04) to indicate test information.

The Hexadecimal number is based on 16, using numbers and letters to identify a value: 0, 1, 2, 3, 4, 5,

6. 7, 8, 9, A, B, C, D, E, F. This system can convey many values using just four characters.

Good for them, not so good for the technician trying to decipher this number/letter combination.


Fortunately, some scan tool Fortunately, some scan tool manufacturers have converted the manufacturers have converted the engineering jargon on their tools into engineering jargon on their tools into terms an average person can terms an average person can understand. understand.

For a technician to use Mode 6, they For a technician to use Mode 6, they need to know some basic terms:need to know some basic terms:

Terms Used in Mode 6 Data1.1. TIDTID = Test Identification – The system being tested (MIDs = Monitor

Identification in CAN systems)

2.2. CIDCID = Component Identification – The component of the system being tested.

3.3. TLTTLT = Test Limit – To pass a test, a test value must be either a minimumminimum or maximum value ( or between a minmin/max value)

4.4. Hexadecimal ($)Hexadecimal ($) = Numeric/Alpha unit that indicates a specific TID/CID or test value (Example: $02)

5.5. Raw DataRaw Data = Numeric data indicating the actual test results.

6.6. Manufacturer’s Conversion FactorManufacturer’s Conversion Factor = A value supplied by the manufacturer, to convert test data to values that can be used to diagnose a system (volts, Ohms, amps, inches of mercury, etc.).

7.7. Test ValueTest Value = Actual test results.

8.8. ResultsResults = Indicates whether system/component either passedpassed or failed a test.

9.9. Limit TypeLimit Type = Test pass/fail limits.

112

MODE 6 DiagnosticsMODE 6 DiagnosticsNow we can apply these definitions to an actual Mode 6 monitor test. Below we see a scan tool read out of an Air/Fuel Sensor monitor test. Fortunately, the scan tool manufacturer provided the definitions of the system being tested, so we did not have to go to the manufacturer’s website to determine which system and component was being tested.The scan tool mfr. has already converted the test data from a hexadecimal code to raw test data.

TID

$06

CID

$01

Test

Air Fuel Ratio Sensor

Test Value

0 ($0000)

Results

Pass

Test Limit

20480 ($5000)

TIDTID = Test Identification

CIDCID = Component Identification

Test ValueTest Value: Actual test results = 00

TLTTLT: Test Limit = 2048020480 (Maximum Limit)

HexadecimalNumber


With a “Test Limit” value of 20480 (maximum) we can see that the “Test Value” (actual test results) of 0 is well below that limit, so the test “Results” is a Pass.

But, what if things were different?

TID

$06

CID

$01

Test


Test Value

0 ($0000)

Results

PassPass

Test Limit

20480 ($5000)

114

MODE 6 DiagnosticsMODE 6 DiagnosticsAn OBD II vehicle indicates that all monitors have been set and passed except for one - the CAT monitor. There are no DTCs, and the tech has tried every drive cycle in the book, with no success.

In desperation, he checks the Mode 6 test results, and finds the following results for the Air/Fuel Sensor monitor test:

TID

$06

CID

$01

Test


Test Value

20475 ($4FFB)

Results

Pass

Test Limit

20480 ($5000)

115

MODE 6 DiagnosticsMODE 6 DiagnosticsQ: Is there a relationship between the Air/Fuel Sensor

“Test Value,” and running the CAT monitor test?A: Possibly. As you can see, the “Test Value” is very near

the maximum limit (almost a fail). Some mfrs. will program their PCM to keep re-testing the Air/Fuel Sensor to see if the original test results were skewed, since it is so close to failing (this programming feature is sometimes applied to zirconium O2 sensor equipped vehicles). Since the CAT monitor cannot run until the Air/Fuel Sensor monitor passes (at a level lower than 20475), the CAT monitor does not rundoes not run. The PCM will continue to run the Air/Fuel sensor monitor test until it gets a better (lower - passed) reading, or a failed reading (above 20480, which sets a DTC).

TID

$06

CID

$01

Test


Test Value

20475

($4FFB)

Results

Pass

Test Limit

20480

($5000)

116

TID

$04

CID

$02

O2 Sensor Heater

Test Value

2591 ($0A1F)

Results

Fail

Minimum Test Limit 2621 ($0A3D)

MODE 6 DiagnosticsMODE 6 DiagnosticsQ: Is there a way a tech can convert the Mode 6 Test ValuesTest Values into

measurements units that can be applied for use with diagnostic test equipment?

A: Yes. The manufacturers do supply a conversion factorconversion factor to assist a technician in diagnosis of a system (see their website).

Below is shown the test results of an Air/Fuel Sensor heater circuit monitor test. As you can see, the Test ValueTest Value did not meet the “Minimum Test Limit” needed to pass the test. To diagnose the circuit yourself, you need to convert the Test ValueTest Value into a unit you can measure (i.e., amperage).

117

MODE 6 DiagnosticsMODE 6 DiagnosticsTo convert the Test ValueTest Value to amperage, you need to multiply the Test ValueTest Value by the mfr. conversion factorconversion factor:

2621 (Minimum monitor test value needed to pass the test) X (times) .000076 (mfg. conversion factormfg. conversion factor) = .19.1991969196 Amps (minimum Amp draw needed to pass the O2 heater monitor test)

2591(Actual monitor test results value) X .000076 (mfr. mfr.

conversion factorconversion factor) = .19.1969166916 Amps (inferred Amps read by PCM during monitor test)

Conversion FactorConversion Factor Chart Supplied by the Manufacturer:

TID

$04

CID

$02

Multiply by 0.000076 0.000076 (Amps)

Maximum HO2S Heater Current(Bank 1 Sensor 2)

Minimum Allowable

Conve

rsio

n Fa

ctor

118


Using the conversion factorconversion factor, the technician now knows two things:• To pass the Air/Fuel sensor heater circuit

monitor test, the Air/Fuel Sensor’s heater circuit needs to draw at leastat least .199196.199196

Amps (199.196 milliamps).

• The monitor test has interpreted that the Air/Fuel Sensor heater circuit is only is only

drawingdrawing .196916.196916 Amps (196.916 milliamps).

119

MODE 6 DiagnosticsMODE 6 DiagnosticsArmed with this new information, the technician can now start testing the Air/Fuel Sensor heater circuit to determine the reason for the low current draw:•High resistance at the circuit ground and/or connectors.•Low source voltage to heater circuit.•Excessive resistance in the Air/Fuel Sensor heater element.

Once the technician repairs the problem, he/she needs to run the monitor to confirm the repair.

120

TSBs, PCM REPROGRAMING,TSBs, PCM REPROGRAMING,& MFR. WEBSITES& MFR. WEBSITES

At the pace that technology is evolving, today’s Smog Check technician cannot

consistentlyconsistently repair emission and driveability problems, unless they use Technical Service Bulletins (TSBs),

PCM Reprogramming, and manufacturer websites.

121

Technical Service Bulletins (TSBs) are Technical Service Bulletins (TSBs) are issued by the vehicle manufacturer to issued by the vehicle manufacturer to

advise technicians that a particular advise technicians that a particular vehicle has a recurring problem. The vehicle has a recurring problem. The

TSB usually includes a repair procedure, TSB usually includes a repair procedure, information on the part(s) that need to information on the part(s) that need to

be replaced, and any warranty be replaced, and any warranty information .information .

Technical Service BulletinsTechnical Service Bulletins

122

After you have identified the initial area After you have identified the initial area causing the emissions/driveability problem, causing the emissions/driveability problem, your next step should be to consult any your next step should be to consult any TSBs that might be related to the identified TSBs that might be related to the identified problem. problem. By not including TSBs in your diagnostic By not including TSBs in your diagnostic process, you risk performing unnecessary process, you risk performing unnecessary diagnostic steps, diagnostic steps, or worseor worse, installing , installing unnecessary parts. unnecessary parts.

Technical Service BulletinsTechnical Service Bulletins

123

TSBs & PCM ReprogrammingTSBs & PCM Reprogramming

Many TSBs require reprogramming (recalibration) Many TSBs require reprogramming (recalibration) of the PCM to fix a known problem(s). Failing to of the PCM to fix a known problem(s). Failing to reprogram a PCM that needs an update can result reprogram a PCM that needs an update can result in wasted diagnostic time, and unnecessary in wasted diagnostic time, and unnecessary repairs. repairs.

Independent repair shops now have access to Independent repair shops now have access to affordable reprogramming equipment. The Society affordable reprogramming equipment. The Society of Automotive Engineers (SAE) has established of Automotive Engineers (SAE) has established standards (SAE2534) for aftermarket tool standards (SAE2534) for aftermarket tool manufacturers to provide “Pass-Thru” PCM manufacturers to provide “Pass-Thru” PCM reprogramming equipment.reprogramming equipment.

124

PCM REPROGRAMMINGPCM REPROGRAMMINGReprogramming a PCM is relatively simple. First obtain the PCM calibration update program from the manufacturer (purchase their CD, or log on to their website). Download the program to a PC, and then follow the instructions provided on the screen.

- NOTE -- NOTE -

It very important that the vehicle have a fully charged battery when reprogramming a PCM. Additionally, DO NOT remove the cable from the PC, or pass-thru module to the PCM during the reprogramming.

125

Contact Mfr. Website Download the PCM Program

Connect Pass-Thru Device to PC and Vehicle

PCM REPROGRAMMINGPCM REPROGRAMMING

Reprogram the Vehicle’s PCM

Download

Program Info

Reprogram

126

Vehicle manufacturers must provide a website for diagnostic and repair information on their vehicles at a reasonable cost. A list is on the National Automotive Service Task Force (NASTF) website:

http://www.nastf.org

Example:Example: A manufacturer’s website charges under $30.00 to download (during a 24 hour period) a PCM calibration update program (using an SAE J2534 pass-thru device). Pass-thru devices cost from $1,300 -$1,600.

Manufacturer WebsitesManufacturer Websites

http://www.nastf.org/

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CASE STUDYA 1996 Ford V-8 (5.0L) was failing the ASM A 1996 Ford V-8 (5.0L) was failing the ASM 50/15 test for high NOx. The technician 50/15 test for high NOx. The technician diagnosed a ‘no EGR flow’ (i.e., vacuum) diagnosed a ‘no EGR flow’ (i.e., vacuum) condition at that speed/load; but he did get condition at that speed/load; but he did get flow (EGR vacuum) during the 25/25 test.flow (EGR vacuum) during the 25/25 test.After hours of checking the EGR valve After hours of checking the EGR valve operation, vacuum hose routing, and other operation, vacuum hose routing, and other input sensors and grounds, he checked to see input sensors and grounds, he checked to see if there was a TSB on this problem. Ford had a if there was a TSB on this problem. Ford had a PCM calibration update that would address this PCM calibration update that would address this problem. He downloaded the program into the problem. He downloaded the program into the vehicle’s PCM, EGR vacuum was restored and vehicle’s PCM, EGR vacuum was restored and the vehicle’s NOx problem was cured – no bad the vehicle’s NOx problem was cured – no bad parts, just a PCM update.parts, just a PCM update.

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BAR Update Issues:BAR Update Issues:

• CAP Related Issues:

• Inspection Issues:

• Repair Issues:

• Testing Equipment Issues:

• Test-Only Issues:

• Training Issues:

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Issue: Should all shops inform customers whose vehicle fails a Smog Check inspection about the CAP program?

• Comment: Yes. Test and Repair stations have an obligation to have a “Notice to Motorists” sign posted in an area consumers frequent and the station personnel should advise consumers in need of smog check repairs of the CAP program. Test-Only shop owners and technicians should alert consumers to the Consumer Assistance Program (CAP) program. CAP provides financial assistance for qualified owners whose vehicles fail their biennial (every-other-year) Smog Check. Motorists may qualify for Repair Assistance in one of two ways:

– Income Eligible – Motorists whose household incomes are at or below 200% of the federal poverty guidelines qualify for up to $500 in repair assistance. Qualified consumers must pay the first $20 towards diagnosis and/or emissions-related repairs.

– Test-Only Eligible – Certain vehicles are required to have their Smog Check inspections done at Test-Only stations. If the vehicle’s DMV registration renewal notice requires a Test-Only inspection, the vehicle may qualify for up to $500 in repair assistance. Qualified consumers must pay the first $100 towards diagnosis and/or emissions-related repairs.

Shop owners, technicians, and consumers can obtain CAP program information and a CAP application by visiting the BAR Web site at www.smogcheck.ca.gov or by calling the Department of Consumer Affairs Consumer Information Center at 1-800-952-5210.

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Issue: If the check engine light comes on during an ASM test, should the vehicle fail the inspection?

• Comment: No. To minimize failures due to vehicle incompatibility (false failures), BAR revised the procedures to only fail a vehicle if the check engine light comes on during a functional test. The test procedure says to assess MIL pass/fail status only during the MIL functional test part of the vehicle’s Smog Check inspection.

This does not apply to OBD II vehicles because the MIL illumination is an automatic fail made by the BAR 97. However, in OBD I vehicles, the MIL light may light for non emission related codes. By following the MIL functional test procedure, as described in the Smog Check Inspection Manual, technicians can minimize the potential for MIL illumination for non emission related codes.

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Issue: Should the technician run a “complete” Smog Check, even if the technician senses the vehicle will fail the emissions test?

• Comment: Yes. If the customer authorizes a full inspection, the technician needs to run a complete test on the vehicle. It may be appropriate for the technician to discuss the pre-inspection option with the customer. In order for a consumer to qualify for CAP, they will need to have a complete initial Smog Check Inspection, or an official pre-inspection. Aborted tests or Training mode tests are not acceptable

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Issue: Are some Smog Check Technicians incorrectly performing the visual inspection for tampered emission control systems?

• Comment: Yes. Technicians MUST verify that all required emission control systems/devices are present and free of tamper(s) and/or defects as defined in the Smog Check Inspection Manual. Technicians shall enter the results of the visual inspection, as prompted by the analyzer. If any required emission control system is tampered (missing, modified, disconnected) or defective, the vehicle shall fail the Smog Inspection.

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Issue: Should Smog Check technicians check ignition timing as part of the Smog Check inspection?

• Comment: Yes, except for vehicles with an under hood label that states “non adjustable” and/or vehicles with computer controlled ignition systems that do not have conventional timing adjustments. For all other vehicles, checking the ignition timing is a required procedure during the Smog Check inspection.

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Issue: Are some technicians not repairing vehicles to the “average” emission levels shown on the VIR?

• Comment: Technicians must perform a full emission failure diagnosis prior to making any repair recommendations to the customer. The diagnosis and repair should be based upon restoring the vehicle to original manufacturer specifications. Repairing a vehicle in this manner will likely result in emission readings well within the average emission levels . An attempt to repair a vehicle just to the pass the fail point. is a disservice to the consumer who expects their vehicle to be repaired to manufacturer standards.

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Issue: Can one Smog Check technician enter another technician’s repairs?

• Comment: Yes. The repairs must be entered as prompted by the analyzer. However, this does not mean that one technician can perform a partial or full smog inspection for another technician.

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Issue: How should a technician handle a vehicle that won’t communicate during an OBD II functional test, but the scan tool says the vehicle is OK and the vehicle is not listed in Appendix J?

• Comment: The OBD II functional test must not be overridden. The customer should either be sent to another station where the BAR 97 EIS can communicate with the vehicle, or be referred to the Referee.

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Issue: Are Test-Only stations required to give estimates to customers for initial inspections or free retests?

• Comment: Yes. Regulations require that a station provide each customer a written estimate of work to be performed, prior to performing any service or repair, even if there is no charge for the service or repair. [See Section 9884.9(a) of the Business & Professions (B&P) Code, and section 3353(a) of the California Code of Regulations (CCR)].

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Issue: Are Test-Only stations required to obtain customers authorization on the work order prior to testing?

• Comment: Yes. Customer authorization means consent, and shall consist of the customer’s signature on the work order taken before work begins. [Reference sections: 9884.9(a) B&P, and 3353(a) CCR, 3303(k) CCR].

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Issue: Are Test-Only stations and Test and Repair stations required to document a customer’s additional authorization for services and repairs?

• Comment: Yes. Test-Only stations and Test & Repair stations must list all: authorization, service work, and parts on the work order and the repair facility and customer invoice; even if there is no charge for the service or repair. Stations are required to comply with sections 9884.9(a) B&P and Section 3353(a) CCR.

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Issue: Are Test-Only technicians allowed to direct customers to specific repair facilities?

• Comment: No. A Test-Only station may not refer a vehicle owner to a particular provider of motor vehicle repair services for emissions related repairs. In accordance with Title 16, Section 3340.16 CCR, Test-Only stations must make available a list, prepared by BAR, of the Smog Check stations in their region. This list can be found on BAR’s Smog Check web site: www.smogcheck.ca.gov, or by contacting a local BAR field office.

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Issue: Should technicians in Test-Only stations run the monitors as part of their Smog Check inspection?

• Comment: No. Technicians in Test-Only stations should perform the Smog Check inspection, per the Smog Check Manual. Since the Smog Check Inspection Manual does not stipulate running monitors as a Test-Only inspection function, the technician shall not run the monitors as part of the Smog Check inspection.

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Issue: Can a Smog Check station sublet its smog inspections to a Test-Only station?

• Comment: No. A Smog Check inspection cannot be sublet.

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Issue: How can a technician determine if an aftermarket part, with a CARB Executive Order (EO) number, is meant for the vehicle they are testing?

• Comment: Technicians are required to verify the EO number as being applicable to the vehicle they are testing. If the part is not applicable to the vehicle they are testing, then the vehicle fails the visual inspection for a modified emission control system part.

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ACKNOWLEDGEMENTSACKNOWLEDGEMENTS

The Bureau of Automotive Repair would like to The Bureau of Automotive Repair would like to thank the following individuals for their thank the following individuals for their contributions to this presentation:contributions to this presentation:• Myron Maurseth – C.I.A.T.Myron Maurseth – C.I.A.T.• Rick Escalambre – Skyline CollegeRick Escalambre – Skyline College• Glenn Richardson – Star EnviroTech Inc.Glenn Richardson – Star EnviroTech Inc.• Jim Moore – Delphi Inc.Jim Moore – Delphi Inc.• Dave Crippen & Steve Pratt – Dave Crippen & Steve Pratt – Vetronix Bosch GroupVetronix Bosch Group

• Tejinder Singh – WyoTechTejinder Singh – WyoTech• Evan Meyer – Automotive InstructorEvan Meyer – Automotive Instructor• Jerry “G” Truglia – ATTSJerry “G” Truglia – ATTS• Marty Gunn - BARMarty Gunn - BAR

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1 BAR UPDATE 2007 Presented by LONG BEACH CITY COLLEGE ADVANCED TRANSPORTATION TECHNOLOGY CENTER Instructor - Pete Sparks/Cal Macy