GM Service Manual Online
For 1990-2009 cars only

Begin the system diagnosis with Diagnostic System Check - Vehicle. The Diagnostic System Check - Vehicle 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 DTCs and the codes status.

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

Visual/Physical Inspection

    • Inspect for aftermarket devices which could affect the operation of the vehicle. Refer to Checking Aftermarket Accessories.
    • 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.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

    • Item must have some data.
    • Item must have some data.