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 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 modules:
  3. • Continuously Variable Road Sensing Suspension (CVRSS) Module
    • Electronic Brake Control Module (EBCM)
    • Powertrain Control Module (PCM)

Does the scan tool communicate with all of the listed 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 modules:

    • Continuously Variable Road Sensing Suspension (CVRSS) Module
    • Electronic Brake Control Module (EBCM)
    • Powertrain Control Module (PCM)

Does the scan tool display any DTCs?

Go to Step 4

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

4

Does the scan tool display any DTCs which 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 any PCM DTCs?

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

Go to Step 6

6

Does the scan tool display any EBCM DTCs?

Go to Diagnostic Trouble Code (DTC) List in ABS Traction Control

Go to Step 7

7

Does the scan tool display DTC C0550?

Go to DTC C0550

Go to Step 8

8

Does the scan tool display DTC C0563?

Go to DTC C0563

Go to Step 9

9

Does the scan tool display DTC C0695?

Go to DTC C0695

Go to Step 10

10

Does the scan tool display DTC C0896?

Go to DTC C0896

Go to Diagnostic Trouble Code (DTC) List