GM Service Manual Online
For 1990-2009 cars only

How to Use This Section

This section provides the following information:

    • General diagnosis information on transmissions
    • Procedures for diagnosing the transmission

When you diagnose any condition of the transmission, begin with Diagnostic Starting Point - Automatic Transmission. This procedure indicates the proper path of diagnosing the transmission by describing the basic checks. This procedure will then refer you to the locations of specific checks. After you have determined the cause of a condition, refer to Repair Instructions for repair procedures.

Diagnosis

Caution: If you probe a wire with a sharp instrument and do not properly seal the wire afterward, the wire corrodes and an open circuit results.

Diagnostic test probes are now available that allow you to probe individual wires without leaving the wire open to the environment. These probe devices are inexpensive and easy to install, and they permanently seal the wire from corrosion.