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. Checks for diagnostic trouble codes (DTCs) in the body control module (BCM) and the powertrain control module (PCM).

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 (BCM) and the powertrain control module (PCM).

Does the scan tool communicate with the BCM and PCM?

Go to Step 3

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

3 | Select the BCM and PCM display DTCs function on the scan tool. Does the scan tool display any DTCs? | Go to Step 4 | Go to Symptoms - Automatic Transmission Shift Lock Control
4 | Does the scan tool display any DTCs which begin with a "U"? | Go to Diagnostic Trouble Code (DTC) List in Data Link Communications | Go to Step 5
5 | Does the scan tool display DTC B1000? | Go to Diagnostic Trouble Code (DTC) List in Body Control System | Go to Step 6
6 | Does the scan tool display DTC B2707 or B2708? | Go to Diagnostic Trouble Code (DTC) List | Go to Symptoms - Automatic Transmission Shift Lock Control