For 1990-2009 cars only
Important: The following steps must be completed before using the symptom tables.
- Perform the Diagnostic System Check - Cellular Communication before using the Symptom Tables in order to verify that all of the following are true:
- Review the system operation in order to familiarize yourself with the system functions. Refer to OnStar Description and Operation .
| • | There are no DTCs set. |
| • | The control module(s) can communicate via the serial data link. |
Visual/Physical Inspection
| • | Inspect for aftermarket devices which could affect the operation of the system. Refer to Checking Aftermarket Accessories in Wiring Systems. |
| • | Inspect the easily accessible or visible system components for obvious damage or conditions which 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:
