Diagnostic System Check

Diagnostic Chart:

The "On-Board Diagnostic System Check" is an organized approach for identifying a problem caused by the on-board computer controlled systems. Understanding this chart and using it correctly will reduce diagnosis time and prevent the unnecessary replacement of parts. If you have not reviewed the basic information on how to use the computer self-diagnostics, then you should do so.

NOTES ON TROUBLE TREES

1. If diagnostic system is not functional, a problem might be present in the ACAC or related system. (This could mean that the diagnostic system has detected a problem in the data line that connects all of the computer systems together. This will also stop all Tech 1 communication. Refer to DATA LINK CONNECTOR. Data Link Connector

2. If diagnostic trouble codes are present, they should be diagnosed in the order shown for that system.

3. If no diagnostic trouble codes are present, then the chart below will guide you to subsystem references for symptom diagnosis.

If no DTCs are set, refer to the "System Checks"/"Symptom Tables" in the system exhibiting the condition:


ABS/TCS
Refer to Brakes and Traction Control Brakes and Traction Control

ENGINE STARTING, DRIVEABILITY, OR EMISSIONS
Refer to Powertrain Management Powertrain Management

PCM AND ENGINE CONTROLS
Refer to Computers and Control Systems Computers and Control Systems

ILLUMINATED ENTRY SYSTEM, INTERIOR LIGHTING
Refer to Lighting and Horns Lighting and Horns

RETAINED ACCESSORY POWER
Refer to Accessories and Optional Equipment Accessories and Optional Equipment

SIR SYSTEM
Refer to Air Bags Restraints and Safety Systems

TWILIGHT SENTINEL, DAYTIME RUNNING LAMPS
Refer to Lighting and Horns Lighting and Horns

VARIABLE EFFORT STEERING
Refer to Steering and Suspension Steering and Suspension

EXTERIOR LIGHTS
Refer to Lighting and Horns Lighting and Horns

PASS-Key(R)II DIAGNOSIS
Refer to Locks Locks