Diagnostic Routine E

Diagnostic Routine E

Diagnostic Overview

The Heated Mirror Is Inoperative

Refer to Wiring Diagram Set 124 for schematic and connector information Electrical Diagrams.

Refer to Wiring Diagram Set 56 for schematic and connector information Electrical Diagrams.

Normal Operation and Fault Conditions

When rear window defrost is activated, (button is on FCIM (Front Controls Interface Module), touchscreen or voice command) the HVAC (Heating, Ventilation, and Air Conditioning) module provides ground to the rear window defrost relay coil causing the contacts in the relay to close. Voltage is supplied to the heated mirror glass to heat the mirrors. The exterior rear view heated mirrors do not share a common ground.

Visual Inspection and Diagnostic Pre-checks

- Inspect BJB (Battery Junction Box) fuse 50 (15A).

- Inspect the exterior mirror glass.

- Inspect the exterior mirror.

Pinpoint Test

1. CHECK THE OPERATION OF THE REAR WINDOW DEFROST SYSTEM

1. With the engine running, activate the rear window defrost.

2. Using an infrared temperature gun or equivalent, measure the temperature of the rear window glass for approximately 30 seconds, noting changes in temperature.

Does the temperature of the rear window glass rise?








2. CHECK THE OPERATION OF THE HEATED EXTERIOR REAR VIEW MIRRORS

1. With the rear window defrost activated, using an infrared temperature gun or equivalent, measure the temperature of the RH (Right Hand) and LH (Left Hand) exterior rear view mirror glass for approximately 30 seconds, noting changes in temperature.

Does at least one heated mirror glass operate correctly?








3. CHECK FOR VOLTAGE TO BJB (Battery Junction Box) FUSE 50 (15A)

1. Verify BJB (Battery Junction Box) fuse 50 (15A) is installed.

2. Ignition ON.

3. With the engine running, activate the rear window defrost.

4. Measure:





Is the voltage greater than 11 volts?








4. CHECK THE VOLTAGE TO THE INOPERATIVE HEATED EXTERIOR REAR VIEW MIRROR GLASS

1. Ignition OFF.

2. Disconnect: Inoperative LH (Left Hand) or RH (Right Hand) Heated Exterior Mirror.

3. Ignition ON.

4. With the engine running, activate the rear window defrost.

5. For inoperative LH (Left Hand) heated mirror, measure:





6. For inoperative RH (Right Hand) heated mirror, measure:





Is the voltage greater than 11 volts?








5. CHECK THE INOPERATIVE EXTERIOR REAR VIEW MIRROR GROUND CIRCUIT FOR AN OPEN

1. Ignition OFF.

2. For inoperative LH (Left Hand) heated mirror, measure:





3. For inoperative RH (Right Hand) heated mirror, measure:





Is the resistance less than 3 ohms?