For 1990-2009 cars

### 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 symptom list in Symptoms will determine the correct diagnostic procedure to use.

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 | Did you perform the Battery Inspection/Test? | Go to Step 2 | Go to Battery Inspection/Test
2 |

1. Install a scan tool
2. Turn ON the ignition, with the engine OFF.

Does the scan tool power up?

Go to Step 3

Go to Scan Tool Does Not Power Up in Data Link Communications

3 | Attempt to establish communication with the following components:

• | Body Control Module (BCM)

• | Instrument Panel Cluster (IPC)

• | Powertrain Control Module (PCM)

Does the scan tool communicate with the BCM, IPC, Immobilizer and PCM?

Go to Step 4

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

4 | Select the BCM, Immobilizer and PCM display DTC function on the scan tool. Does the scan tool display any DTCs? | Go to Step 5 | Go to Symptoms - Engine Electrical
5 | Does the scan tool display any DTCs which begin with U? | Go to Scan Tool Does Not Communicate with Class 2 Data Line in Data Link Communications | Go to Step 6
6 | Does the scan tool display DTCs B1973, B1982 or B1983? | Go to Diagnostic Trouble Code (DTC) List/Type in Body Control System | Go to Symptoms - Engine Electrical