For 1990-2009 cars only
Important: The following steps must be completed before using the symptom tables:
- Perform the Diagnostic System Check for the subsystem exhibiting the symptoms. Refer to Control Module References in Body Control System. The subsystem diagnostic system check will identify where to begin diagnosis of the data link communication system.
- Review the system operation in order to familiarize yourself with the system functions. Refer to Data Link Communications Description and Operation .
Visual/Physical Inspection
| • | Inspect for aftermarket devices that could affect the operation of the serial data communications systems. Refer to Checking Aftermarket Accessories in Wiring Systems. |
| • | Inspect the easily accessible systems or visible system components for obvious damage or conditions that could cause the symptom. |
Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:
