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 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.

3. The listed DTCs are internal module malfunctions and should be corrected before attempting any other diagnostics.

4. The listed DTCs are battery voltage related malfunctions and should be corrected before attempting any other diagnostics.

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 specified modules?

Go to Step 3

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

3 |

1. Select the PCM display DTCs function on the scan tool.
2. Select the BCM display DTCs function on the scan tool.

Does the scan tool display any DTCs for the modules?

Go to Step 4

Go to Symptoms - Theft Deterrent

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 P0601-P0607, P1600, P1621 or P1627? | Go to Diagnostic Trouble Code (DTC) List 2.4L or Diagnostic Trouble Code (DTC) List 3.4L in Engine Controls | Go to Step 6
6 | Does the scan tool display DTC B1000, B1004, B1007, or B1009? | Go to Diagnostic Trouble Code (DTC) List in Body Control System | Go to Step 7
7 | Does the scan tool display DTC P0562, P0563, P0621or P0622? | Go to Diagnostic Trouble Code (DTC) List in Engine Electrical | Go to Diagnostic Trouble Code (DTC) List