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. 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.

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. • Body Control Module (BCM)
    • Electronic Brake Control Module (EBCM)
    • Powertrain Control Module (PCM)

Does the scan tool communicate with the control modules?

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:

    • Body Control Module (BCM)
    • Electronic Brake Control Module (EBCM)
    • 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 which begin with a "U"?

Go to Step 5

Go to Step 6

5

Does the scan tool display any DTCs within the range U2000-U2007?

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

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

6

Does the scan tool display DTC B1000, B1001, B1009, B1369, B1374, or B1379?

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

Go to Step 7

7

Does the scan tool display DTC P0560 or P0620?

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

Go to Diagnostic Trouble Code (DTC) List