GM Service Manual Online
For 1990-2009 cars only

Test Description

The number(s) below refer to the step number(s) 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. This step checks for DTCs in the control modules related to the operation of the instrument panel cluster.

  3. The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.

  4. This step checks for an internal malfunction of the instrument panel cluster.

  5. This step checks for a high/low vehicle system voltage condition.

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 modules:
  3. • The body control module (BCM)
    • The electronic brake control module (EBCM)
    • The instrument panel cluster
    • The powertrain control module (PCM)
    • The inflatable restraint sensing and diagnostic module (SDM)

Does the scan tool communicate with the 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 DTCs function on the scan tool for the following control modules:

    • The BCM
    • The EBCM
    • The instrument panel cluster
    • The PCM
    • The SDM

Does the scan tool display any DTCs for the control modules listed above?

Go to Step 4

Go to Symptoms

4

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

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

Go to Step 5

5

Does the scan tool display DTC B0602 or B1000?

Go to Diagnostic Trouble Code (DTC) List/Type

Go to Step 6

6

Does the scan tool display DTC P0560 or P0620 in the PCM?

Go to Diagnostic Trouble Code (DTC) List/Type in Engine Controls - 3.1L (LG8) or Diagnostic Trouble Code (DTC) List/Type in Engine Controls - 3.8L

Go to Diagnostic Trouble Code (DTC) List/Type