GM Service Manual Online
For 1990-2009 cars only

Begin the system diagnosis with the Diagnostic System Check - Door Systems . The Diagnostic System Check will provide the following information:

    • The identification of the control modules which command the system.
    • The ability of the control modules to communicate through the serial data circuit.
    • The identification of any stored diagnostic trouble codes (DTCs) and their status.

The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

    • Inspect for aftermarket devices which could affect the operation of the door 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.
    • Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.