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. There may be DTCs stored in other class 2 modules related to the instrument cluster.

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
--- | --- | --- | ---
Schematic Reference: Instrument Cluster Schematics
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 control modules:

• | Powertrain Control Module (PCM)

• | Transmission Control Module (TCM)

Does the scan tool communicate with the control modules listed above?

Go to Step 3

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

3 | Attempt to communicate with the 4WAL 3 Sensor (EBCM). Does the scan tool communicate with the EBCM? | Go to Step 4 | Go to Scan Tool Does Not Communicate with Electronic Brake Control Module in Data Link Communications
4 | Select the display DTCs function on the scan tool for the following control modules:

• | EBCM

• | PCM

• | TCM

Does the scan tool display any DTCs for the control modules listed above?

Go to Step 5

Go to Symptoms - Instrument Panel, Gages and Console

5 | 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 and to Scan Tool Does Not Communicate with Electronic Brake Control Module in Data Link Communications | Go to Step 6
6 | Does the scan tool display DTC P0562, P0563, P1637 or P1638? | Go to Diagnostic Trouble Code (DTC) List in Engine Electrical | Go to Diagnostic Trouble Code (DTC) List