GM Service Manual Online
For 1990-2009 cars only

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.

  2. The symptom list in Symptoms will determine the correct diagnostic procedure to use.

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 ON the ignition, with the engine OFF.
  2. Attempt to establish communication with the following control modules:
  3. • The Electronic Brake Control Module (EBCM)
    • The Instrument Panel Cluster (IPC)
    • The Powertrain Control Module (PCM)

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

Go to Step 3

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

3

Select the display DTC function on the scan tool for the following control modules:

    • The Electronic Brake Control Module (EBCM)
    • The Instrument Panel Cluster (IPC)
    • The Powertrain Control Module (PCM)

Does the scan tool display any DTCs?

Go to Step 4

Go to Symptoms - Cruise Control

4

Does the scan tool display any DTCs that begin with a "U"?

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

Go to Step 5

5

Does the scan tool display DTC B1652, B1656 or B1657?

Go to Diagnostic Trouble Code (DTC) List in Body Control Systems

Go to Step 6

6

Does the scan tool display DTC B1982, B1983, P0560 or P0620?

Go to Diagnostic Trouble Code (DTC) List in Engine Electrical

Go to Diagnostic Trouble Code (DTC) List