General Service

The diagnostic flow charts contained are used to find and repair malfunctions which the self-diagnostics of the module have found. If a diagnostic trouble code (DTC) is a history DTC, the malfunction may be intermittent. Try wiggling wiring and connectors as this can often cause the malfunction to appear. It is not recommended to replace modules based on history codes.

It is recommended to use a Scan tool in performing system diagnostics. The Scan tool special functions (shown in the diagnostics) will assist in diagnosing OnStar communication interface module related malfunctions. The diagnostic flow charts rely on information from the Scan tool to make repair decisions.