GM Service Manual Online
For 1990-2009 cars only

Begin the system diagnosis with Diagnostic System Check - Vehicle . The Diagnostic System Check provides the following information:

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

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

Symptoms

When it has been determined through Diagnostic System Check - Vehicle , that no DTCs are present. If it is determined that a malfunction exists, identify the concern by referring to the Symptoms - Automatic Transmission table. The Symptoms - Automatic Transmission table provides common diagnostic categories which relate directly to diagnostic information or procedures.