The driver door switch (DDS) and passenger door switch (PDS) 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 module supplies B+ through the driver/passenger mirror heating element supply voltage circuit when a request is seen. Ground is applied through the driver/passenger mirror heating element low reference circuit.

Schematic Reference

Outside Rearview Mirror Schematics

Connector End View Reference

Mirror Connector End Views

Description and Operation

Outside Mirror Description and Operation

Electrical Information Reference

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. Press the rear window defogger switch. Verify both the left and right outside mirror glass become warm.

1. Ignition OFF, disconnect the harness connector C1 at the outside rearview mirror.
2. Ignition OFF, test for less than 300 ohms of resistance between the low reference circuit terminal 3 and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the appropriate door module.

3. Connect a test lamp between the supply voltage circuit terminal 4 and ground.
4. Ignition ON, command the 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 supply voltage circuit for a short to voltage. If the circuit tests normal, replace the appropriate door module.

⇒	If the test lamp is always OFF, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the appropriate door module.

5. If all circuits test normal, test or replace the outside rearview mirror face.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.