GM Service Manual Online
For 1990-2009 cars only

Begin the system diagnosis with Diagnostic System Check - Vehicle in Vehicle DTC Information. The Diagnostic System Check - Vehicle will provide the following information:

    • The identification of the control modules which are not communicating.
    • The identification of any stored diagnostic trouble codes (DTCs) and their status.

The use of the Diagnostic System Check - Vehicle will identify the correct procedures to begin vehicle diagnosis. These must be performed before system DTC or symptom diagnosis.