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 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 control module indicating that the rear defrost system is active. The door module 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 element low reference circuit.

Circuit/System Verification

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. Testing and Inspection

2. Press the rear window defogger switch. Verify both the left and right outside mirror glass become warm.
3. If all circuits test normal, test or replace the inoperative outside rearview mirror.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector X1 (RPO DS3) or X2 (RPO DNP) 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 switch.

3. Connect a test lamp between the control circuit terminal 7 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 control circuit for a short to voltage. If the circuit tests normal, replace the appropriate door switch.
^ 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 appropriate door switch.

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

Repair Instructions

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

* Outside Rearview Mirror Glass Replacement