Inside Rearview Mirror Lamp(s) Inoperative

Inside Rearview Mirror Lamp(s) 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.

Diagnostic Fault Information





Circuit/System Description

The INT LIGHT fuse supplies battery voltage to the inadvertent load control relay located in the body control module (BCM). The BCM applies ground to the inadvertent relay control circuit which energizes the inadvertent load control relay coil. With the relay coil energized, the switch contacts close allowing battery voltage to flow from the INT LIGHT fuse to the inside rearview mirror lamps through the inside rearview mirror lamps supply voltage circuit. The inside rearview mirror lamps are controlled by a 3 position (OFF, DOOR, ON) switch. When the inside rearview mirror switch is placed in the DOOR position, the lamps are controlled by the BCM by grounding the courtesy lamp control circuit. When any door is opened, the jam switch contacts close and the BCM receives a door-open input. If the BCM receives a door lock or unlock input, the BCM will activate the inadvertent relay control circuit, providing battery voltage to the inside rearview mirror lamps. The BCM also provides ground to the inside rearview mirror lamps through the courtesy lamp control circuit.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the inside rearview mirror.
2. Test for less than 1.0 ohm of resistance between the ground circuit and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Open the drivers door and test for less than 1.0 ohm of resistance between the courtesy lamp low control circuit and ground.

• If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

4. Ignition ON, verify that a test lamp illuminates between the inside rearview mirror lamps supply voltage circuit and ground.

• If the test lamp does not illuminate, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, replace the inside rearview mirror.

Repair Instructions

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

* Rearview Mirror Replacement
* Control Module References for BCM replacement, setup, and programming Programming and Relearning