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. 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.

  3. Uses the scan tool to determine if there are any codes in the Radio module.

  4. 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.

  5. The presence of DTC B1327 indicates that there is a vehicle battery problem. The vehicle battery needs to be in the proper state of charge before continuing entertainment system diagnosis.

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 radio.

Does the scan tool communicate with the radio?

Go to Step 3

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

3

Is the vehicle equipped with rear seat entertainment RPO U32?

Go to Step 4

Go to Step 5

4

  1. Turn ON the ignition, with the engine OFF.
  2. Use the scan tool class 2 message monitor to communicate with the DVD player (CDX) and the Rear Video/Audio/HVAC Module (RVAC).

Does the scan tool communicate with the DVD player and the Rear Video/Audio/HVAC Module (RVAC)?

Go to Step 5

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

5

Select the radio display DTCs function on the scan tool.

Does the scan tool display any DTCs?

Go to Step 6

Go to Symptoms - Entertainment

6

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 7

7

Does the scan tool display DTC B1000, B1004 or B1009?

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

Go to Step 8

8

Does the scan tool display DTC B1001, B1780 or B1025?

Go to Diagnostic Trouble Code (DTC) List

Go to Step 9

9

Does the scan tool display DTC B1327?

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

Go to Symptoms - Entertainment