GM Service Manual Online
For 1990-2009 cars only

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

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

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