The Driver Door Module (DDM) and Passenger Door Module (PDM) supply voltage to the outside rearview mirror heater elements upon receipt of a serial data message from the HVAC module indicating that the rear defrost system is active. The door switch supplies B+ through the driver/passenger mirror heating element control circuit when a request is seen. Ground is applied through the driver/passenger mirror heating low reference circuit.

Schematic Reference

Outside Rearview Mirror Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Outside Mirror Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information.

1. Ignition ON, press the rear window defogger switch. Verify the rear window defogger indicator illuminates.

⇒	If the rear window defogger indicator does not illuminate, refer to Rear Window Defogger Malfunction.

2. Rear window defogger ON, verify both the left and right outside mirror glass become warm.

1. Ignition OFF, disconnect the X3 harness connector at the appropriate door module.
2. Ignition ON, verify a test lamp does not illuminate between the control circuit terminal 7 and ground.

⇒	If the test lamp illuminates, test the control circuit for a short to voltage.

3. Ignition OFF, test for infinite resistance between the control circuit terminal 7 and ground.

⇒	If less than the specified value, test the control circuit for a short to ground. If the circuit tests normal, test or replace the rearview mirror glass.

4. Test for 5-10 ohms between the control circuit terminal 7 and the low reference circuit terminal 3.

⇒	If not within the specified range, test the control circuit and the low reference circuit for an open/high resistance. If the circuits test normal, test or replace the rearview mirror glass.

5. If all circuits test normal, test or replace the door module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.