Diagnostic Starting Point

For the Automatic Day-Night Mirror and Rear Window Defogger (W/O C68) systems, begin the diagnosis by reviewing the system Description and Operation. Reviewing the Description and Operation information will help you determine the correct symptom diagnostic procedure when a malfunction exists. Reviewing the Description and Operation information will also help you determine if the condition described by the customer is normal operation. Refer to Symptoms - Heated Glass Element in order to identify the correct procedure for diagnosing the system and where the procedure is located. Symptom Related Diagnostic Procedures

For the Rear Window Defogger (W/C68) system, begin the diagnosis with the Diagnostic System Check - Defogger. The Diagnostic System Check will provide the following information:
^ The identification of the control module(s) which command 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 Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

"For a description of the RPO Code(s) shown in this article or any of the images therein, refer to the RPO Code List found at Vehicle/Application ID". RPO Codes