Advanced Engine Performance Diagnosis · Advanced Engine Performance Diagnosis, Sixth Edition James D. Halderman •OBD-II Freeze-Frame To assist the service technician, OBD II required

Advanced Engine Performance Diagnosis

CHAPTER

Advanced Engine Performance Diagnosis, Sixth EditionJames D. Halderman

SIXTH EDITION

Copyright © 2016, 2012, 2009 by Pearson Education, Inc.All Rights Reserved

The Diagnostic Process

1



OBJECTIVES

• Prepare for ASE (Automotive ServiceExcellence) computerized enginecontrols diagnosis (A8) certification testcontent area “E.”

• List the steps of the diagnostic process.

• Describe the simple preliminary teststhat should be performed at the start ofthe diagnostic process.



OBJECTIVES

• List six items to check as part of a thorough visual inspection.

• Explain the troubleshooting procedures to follow if a diagnostic trouble code has been set.

• Explain the troubleshooting procedures to follow if no diagnostic trouble code has been set.



OBJECTIVES

• Discuss the type of scan tools that are used to assess vehicle components.

• Describe the methods that can be used to reprogram (reflash) a vehicle computer.



THE EIGHT-STEP DIAGNOSTIC PROCEDURE

• A strategy that eliminates known-good components or systems in order to find the root cause of automotive engine performance problems.

All vehicle manufacturers recommend a diagnostic procedure, and the plan suggested in this chapter combines most of the features of these plans plus additional steps developed over years of real-world problem solving.




• Verify the Problem (Concern)

• Perform a Thorough Visual Inspection and Basic Tests

Check for obvious problems (basics, basics, basics)

Check everything that does and does not work

Look for evidence of previous repairs

Check oil level and condition




Check coolant level and condition

Use the paper test

Ensure adequate fuel level

Check the battery voltage

Check the spark using a spark tester

Check the fuel pump pressure

• Retrieve the Diagnostic Trouble Codes (DTCs)




• Check for Technical Service Bulletins (TSBs)

• Look Carefully at Scan Tool Data

• Narrow the Problem to a System or Cylinder

• Repair the Problem and Determine the Root Cause

• Verify the Repair and Clear Any Stored DTCs



SCAN TOOLS

• Scan tools are the workhorse for any diagnostic work on all vehicles.

• Scan tools can be divided into two basic groups:

Factory scan tools.

Aftermarket scan tools



Figure 1.11 A TECH 2 scan tool is the factory scan tool used on General Motors vehicles.



Figure 1.12 A Bluetooth adapter that plugs into the DLC and transmits global OBD II information to a smart phone that has a scan tool app installed.



TROUBLESHOOTING USING DIAGNOSTIC TROUBLE CODES

• Pinning down causes of the actual problem can be accomplished by trying to set the opposite code.

For example, if a code indicates an open throttle position (TP) sensor (high resistance), clear the code and create a shorted (low-resistance) condition.

• This can be accomplished by using a jumper wire and connecting the signal terminal to the 5-volt reference terminal.



FLASH CODE RETRIEVAL ON OBD-I GENERAL MOTORS VEHICLES

• The GM system uses a “check engine”or “check engine soon” MIL to notify the driver of possible system failure.

• Under the dash (on most GM vehicles) is a data link connector (DLC) previously called an assembly line communications link (ALCL) or assembly line diagnostic link (ALDL).



FLASH CODE RETRIEVAL ON OBD-I GENERAL MOTORS VEHICLES

Most General Motors diagnostic trouble codes can be retrieved by using a metal tool and contacting terminals A and B of the 12-pin DLC.



Figure 1.13 To retrieve flash codes from an OBD-I General Motors vehicle, without a scan tool, connect terminals A and B with the ignition on–engine off.



RETRIEVING FORD DIAGNOSTIC CODES

• The best tool to use during troubleshooting of a Ford vehicle is a self-test automatic readout (STAR) tester, new generation STAR (NGS), WDS (Worldwide Diagnostic System), or another scan tool with Ford capabilities.



RETRIEVING FORD DIAGNOSTIC CODES

If a STAR tester or scan tool is not available, a needle (analog) type of voltmeter can be used for all OBD-I (prior to 1996) systems.



Figure 1.14 Diagnostic trouble codes (DTCs) from Chrysler and Dodge vehicles can be retrieved by turning

the ignition switch to on and then off three times.



Figure 1.15 The data link connector (DLC) can be located in various locations.



Figure 1.16 A typical OBD-II data link connector (DLC). The location varies with make and model and may even

be covered, but a tool is not needed to gain access.



OBD-II ACTIVE TESTS

• OBD-II Drive Cycle (The vehicle must be driven under a

variety of operating conditions for all active tests to be performed)

• Types of OBD-II Codes

Type A Codes. (A type A DTC is emission related and will

causes the MIL to be turned on at the first trip if the computer hasdetected a problem)

Type B Codes. (A type B code will be stored as a pending

code in the PCM and the MIL will be turned on only after secondconsecutive trip)

Type C and D Codes. (Type C and D codes are for use

with non-emission-related diagnostic tests)

Trip: is define as an engine-operating drive cycle that contains the

necessary conditions for a particular test to be performed.



• OBD-II Freeze-Frame To assist the service technician, OBD II required the computer to

take a “snapshot” or freeze-frame of all data at the instant anemission-related DTC is set.

The freeze-frame has to contain data value that occurred at thetime the code was set

• Diagnosing Intermittent Malfunctions The different types of conditions that you will see, the hardest to

accuracy diagnose and repair are intermittent malfunctions. Theseconditions may be temperature related (only occur when thevehicle is hot or cold)

OBD-II ACTIVE TESTS



SERVICE/FLASH PROGRAMMING

• Remote Programming Uses the scan tool to transfer data from the manufacturing’s shop

PC to the vehicle’s PCM.

• Direct Programming Direct programming does utilize a connection between the shop PC

and the vehicle DLC.

• Off-Board Programming Off-Board Programming is used if the PCM must be programmed

away from the vehicle (by using Off-Board Programming adapter).



Figure 1.17 The first step in the reprogramming procedure is to determine the current software installed

using a scan tool. Not all scan tools can be used.



Figure 1.18 Follow the on-screen instructions.



Figure 1.19 An Internet connection is usually needed to perform updates although some vehicle

manufacturers use CDs, which are updated regularly at a cost to the shop.



Figure 1.20 Connecting cables and a computer to perform off-board programming.



J2534 REPROGRAMMING

• Legislation has mandated that vehiclemanufacturers meet the SAE J2534(The Society of AutomotiveEngineers)standards for all emissions-related systems on all new vehiclesstarting with model year 2004.

• This standard enables independentservice repair operators to program orreprogram emissions-related ECMsfrom a wide variety of vehiclemanufacturers with a single tool.



Figure 1.21 The J2534 pass-through reprogramming system does not need a scan tool to reflash the PCM on

most 2004 and newer vehicles.



Figure 1.22 A typical J2534 universal reprogrammerthat uses the J2534 standards.



MANUFACTURER’S DIAGNOSTIC ROUTINES

• Each vehicle manufacturer has established their own diagnostic routines and they should be followed. Most include the following steps:

Retrieve diagnostic trouble codes.

Check for all technical service bulletins that could be related to the stored DTC.




If there are multiple DTCs, the diagnostic routine may include checking different components or systems instead of when only one DTC was stored.

Perform system checks.

Perform a road test matching the parameters recorded in the freeze-frame to check that the repair has corrected the malfunction.




Repeat the road test to cause the MIL to be extinguished.



COMPLETING SYSTEM REPAIRS

• After the repair has been successfully completed, the vehicle should be driven under similar conditions that caused the original concern.

• Verify that the problem has been corrected.

• To perform this test drive, it is helpful to have a copy of the freezeframe parameters that were present when the DTC was set.



COMPLETING SYSTEM REPAIRS

• By driving under similar conditions, the PCM may perform a test of the system and automatically extinguish the MIL.



PROCEDURES FOR RESETTING THE PCM

• The PCM can be reset or cleared of previously set DTCs and freeze-frame data in the following ways:

Driving the Vehicle.

Clear DTCs Using a Scan Tool.

Battery Disconnect.



SUMMARY

• Funnel diagnostics—Visual approach to a diagnostic procedure

• A thorough visual inspection is important during the diagnosis and troubleshooting of any engine performance problem or electrical malfunction



SUMMARY

• If the MIL is on, retrieve the DTC and follow the manufacturer’s recommended procedure to find the root cause of the problem.

• OBD-II vehicles use a 16-pin DLC and common DTCs

Documents

Advanced Engine Performance Diagnosis · Advanced Engine Performance Diagnosis, Sixth Edition James D. Halderman •OBD-II Freeze-Frame To assist the service technician, OBD II required