GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The diagnostic system check is an organized method of identifying any problems caused by a malfunction in the instrument panel (IP) system. The service technician must begin diagnosis of any IP complaint with the diagnostic system check. The diagnostic system check directs the service technician to the next logical step in diagnosing the complaint.

Diagnostic Aids

Use the following ordered procedure when servicing the Instrument Cluster. Failure to use the following procedure may cause the loss of important diagnostic data and may lead to difficult and time-consuming diagnosis procedures.

  1. Use the following procedure to perform a vehicle preliminary diagnosis inspection:
  2. 1.1. Inspect the engine cooling system for leaks.
    1.2. Insure the cooling system is full.
    1.3. Inspect the engine for oil leaks.
    1.4. Insure the engine oil is full.
    1.5. Inspect the fuel level sender operation.
    1.6. Insure the malfunction indicator lamp (MIL) is operating properly.
  3. Determine if the following conditions exist:
  4. • No DTCs are present.
    • The failure is intermittent and cannot be reproduced.
  5. If the above conditions exist, attempt to reproduce the malfunction, use the automatic snapshot feature of the Scan Tool while test driving the vehicle. Perform normal acceleration, stopping, and turning maneuvers during the test drive.
  6. Clear the DTCs after all of the system malfunctions have been corrected.

Diagnosing DTCs in the correct order is very important. Failure to diagnose DTCs in the order specified may result in the following:

    • Extended diagnostic time
    • Incorrect diagnosis
    • Incorrect parts replacement

Step

Action

Yes

No

1

Install a scan tool.

Does the scan tool power up?

Go to Step 2

Go to Scan Tool Does Not Power Up in Data Link Communications

2

  1. Turn the ignition ON.
  2. Use the scan tool in order to establish communications with the following module:
  3. • Electronic Brake Control Module (EBCM)
    • Engine Control Module (ECM)
    • SDM Control Module
    • Anti-Theft Module

Does the scan tool communicate with all of the control modules listed above?

Go to Step 3

Go to Scan Tool Does Not Communicate with Component in Data Link Communications

3

Does the scan tool indicate DTC P0656 and/or P1661 are set?

Refer to the appropriate DTC for diagnosis in Engine Controls 0.8L, or Engine Controls 1.0L

Go to Step 4

4

Is the malfunction indicator lamp (MIL) on all the time or inoperative?

Go to Malfunction Indicator Lamp (MIL) Inoperative , or Malfunction Indicator Lamp (MIL) Inoperative , or Malfunction Indicator Lamp (MIL) Always On in Engine Controls 0.8L, or Malfunction Indicator Lamp (MIL) Always On in Engine Controls 1.0L

Go to Step 5

5

Is the fuel gage inoperative or inaccurate?

Refer to Instrument Panel Description for further diagnosis of the fuel gage

Go to Step 6

6

Are any other instrument panel lamps or gages inoperative or inaccurate?

Refer to Symptoms

Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems and refer to Instrument Panel Description for further explanations of component operations