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 or total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.

  1. The presence of DTCs which begin with "U" indicate some of the modules are not communicating.

Step

Action

Yes

No

1

Install a scan tool.

Does the scan tool power up?

Go to Step 2

Go to in Data Link Communications

2

  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to establish communication with theBCM and PCM control module(s).

Does the scan tool communicate with the control module(s)?

Go to Step 3

Go to in Data Link Communications

3

Select the control module display DTCs function on the scan tool.

Does the scan tool display any DTCs?

Go to Step 4

Go to Symptoms

4

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

Go to in Data Link Communications

Go to Step 5

5

Does the scan tool display DTC B1327 or B1328?

Go to in Engine Electrical

Go to Step 6

6

Does the scan tool display the PCM DTCs P0530 or P1546?

Go to in Engine Controls

Go to Symptoms