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 INTERIOR LIGHTS fuse supplies battery voltage to the body control module (BCM). The BCM applies battery voltage to the courtesy lamps through the courtesy lamp supply voltage 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 or a rear hatch open input, the BCM will activate the courtesy lamp supply voltage circuit, providing battery voltage to all of the instrument panel (I/P) courtesy lamps, rearview mirror lamps, and rear compartment lamps. The courtesy lamps can be manually activated by placing the interior lamp switch in the DOME position. The BCM also provides a class 2 serial data message to the driver door module (DDM) and passenger door module (PDM) to apply battery voltage to the courtesy lamps located on each door. For more detailed information concerning courtesy lamp operation refer to Interior Lighting Systems Description and Operation.

CIRCUIT/SYSTEM TESTING
1. Ignition OFF, disconnect the harness connector at the inside rearview mirror.
2. Test for less than 1 ohm of resistance between the ground circuit terminal 8 and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
3. Test for less than 1 ohm of resistance between the courtesy lamp low control circuit terminal 1 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 courtesy lamp supply voltage circuit terminal 6 and ground.
- If the test lamp does not illuminate, test the courtesy lamp 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