Courtesy Lamps Malfunction

Courtesy Lamps Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



Diagnostic Fault Information






Circuit/System Description

The courtesy lamps are controlled by the body control module (BCM). Inputs from the door ajar switches are monitored by the BCM. When a door ajar switch is closed the BCM supplies the voltage for the courtesy lamps or the dome lamp switch is turned to the ON position.


Reference Information
Schematic Reference

Interior Lights Schematics (Interior Lights Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Interior Lighting Systems Description and Operation (Interior Lighting Systems Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information


Circuit/System Verification

1. Ignition ON, courtesy defeat switch in the OFF position.
2. Open and close each door while observing the scan tool Ctsy. Lamp Actv. Reason parameter . The parameter should change between Door Open and Off.

• If the parameter is always Door Open or always Off, Refer to Door Ajar Indicator Malfunction (Door Ajar Indicator Malfunction) .


• If the parameter is always Manual Defeat, Refer to Courtesy Defeat Switch Malfunction.

3. Open and close the driver door while observing the courtesy lamps. Verify the courtesy lamps turn ON and OFF.

• If the courtesy lamps do not turn ON and OFF, Refer to Courtesy Lamp Inoperative - One or More.




Circuit/System Testing


Courtesy Defeat Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the front dome/map lamp.
2. Verify that a test lamp illuminates between the ground circuit terminal 4 and B+.

• If the test lamp does not illuminate, test the ground circuit for an open/high resistance or short to voltage.

3. Ignition ON, all doors closed, verify the scan tool Ctsy. Lamp Actv. Reason parameter is Off.

• If the parameter is Manual Defeat, test the courtesy defeat signal circuit terminal 25 for a short to ground. If the circuit tests normal, replace the BCM.

4. Connect a 3A fused jumper wire between the courtesy defeat signal circuit terminal 25 and ground. Verify the scan tool Ctsy. Lamp Actv. Reason parameter is Manual Defeat.

• If not the specified value, test the signal circuit for an open/high resistance or short to voltage. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, replace the headlamp switch.




Courtesy Lamp Inoperative - One or More
1. Ignition OFF, disconnect the harness connector at the inoperative courtesy lamp.
2. Verify that a test lamp illuminates between the ground circuit listed below and B+:

* Front Door Courtesy Lamps - terminal 2
* Ignition Key Lamp - terminal F
* Rear Compartment Courtesy Lamps - terminal 1
* I/P Compartment Lamp - terminal 1
* Vanity Mirror Lamps - terminal B
* Front Dome Lamp - terminal 4
* Center Dome Lamp (RPO UUC) - terminal B
* Center Dome Lamp (without RPO UUC) - terminal 2


• If the test lamp does not illuminate, test the ground circuit for an open/high resistance or short to voltage.

3. Open the driver door, verify that a test lamp illuminates between the courtesy lamp control circuit listed below and ground:

* Front Door Courtesy Lamps - terminal 1
* Ignition Key Lamp - terminal E
* Rear Compartment Courtesy Lamps - terminal 2
* I/P Compartment Lamp - terminal 2
* Vanity Mirror Lamps - terminal A
* Front Dome Lamp - terminal 3
* Center Dome Lamp (RPO UUC) - terminal C
* Center Dome Lamp (without RPO UUC) - terminal 3


• If the test lamp does not illuminate, test the control circuit for an open/high resistance or short to ground.

4. Command the Courtesy Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF as commanded.

• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
• 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 BCM.

5. If all circuits test normal, replace the inoperative courtesy lamp.



Repair Instructions

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

* Front Side Door Latch Replacement (Service and Repair)
* Rear Side Door Latch Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming