Heated Mirrors Inoperative

HEATED MIRRORS INOPERATIVE

DIAGNOSTIC INSTRUCTIONS
- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
- Review Strategy Based Diagnosis for an overview of the diagnostic approach.
- Diagnostic Procedure Instructions provides an overview of each diagnostic category.

CIRCUIT/SYSTEM DESCRIPTION
The outside rearview mirrors heat during the defrost/defog cycles for the rear window. The driver door module (DDM) and passenger door module (PDM) control the heated mirror functions. The DDM supplies power and ground to the driver heated mirror and the PDM supplies it to the passenger heated mirror. When the door modules receive a class 2 serial data message from the HVAC control module indicating the rear defogger has been turned ON, both door modules will activate the heated mirror by applying voltage to the heated mirror element feed circuit.

CIRCUIT/SYSTEM TESTING
1. Ignition OFF, disconnect the C1 harness connector at the inoperative outside rearview mirror.
2. Test for less than 1.0 ohm of resistance between the ground circuit terminal B and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit terminal E and the ground circuit terminal B.
4. Command the inoperative mirror heater ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the inoperative door control module.
- If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the inoperative door control module.
5. If all circuits test normal, test or replace the inoperative outside rearview mirror.

REPAIR INSTRUCTIONS
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

- Mirror Replacement
- Control Module References for DDM or PDM replacement, setup, and programming. Programming and Relearning