For 1990-2009 cars

### 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 Body Rear End Symptoms will determine the correct diagnostic procedure to use when no DTCs are present.

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.

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 body control module.

Does the scan tool communicate with the body control module?

Go to Step 3

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

3 | Select the body control module display DTCs function on the scan tool. Does the scan tool display any DTCs? | Go to Step 4 | Go to Diagnostic System Check - Body Rear End
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 DTC B1000 or B1001? | Go to Diagnostic Trouble Code (DTC) List in Body Control System | Go to Diagnostic Trouble Code (DTC) List