Courtesy Lamp

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• 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 body control module (BCM) supplies battery voltage to the dome/reading lamp via the dome lamp control circuit. The reading lamp is controlled by an individual switch that is activated by the operator when additional cabin lighting is required. In the event that the reading lamp were to remain illuminated for more than 10 minutes with the ignition switch in the OFF position and no doors opened, the BCM will deactivate the dome lamp control circuit to prevent total battery discharge.

Reference Information

Schematic Reference

Interior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

1. Ignition OFF, all doors closed, all accessories OFF, disconnect the harness connector at the E37A dome/reading lamps. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 Ω between the ground circuit terminal 6 and ground.


• If 10 Ω or greater


1. Ignition OFF.
2. Test for less than 2 Ω in the ground circuit end to end.


• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, repair the open/high resistance in the ground connection.




• If less than 10 Ω


3. Connect a test lamp between the control circuit terminal 2 and ground.
4. Verify the test lamp turns ON and OFF when commanding the Courtesy Lamps Duty Cycle Command ON and OFF with a scan tool.


• If the test lamp is always OFF


1. Ignition OFF, disconnect the X7 harness connector at the K9 body control module.
2. Test for infinite resistance between the control circuit and ground.


• If less than infinite resistance, repair the short to ground on the circuit.



• If infinite resistance


3. Test for less than 2 Ω in the control circuit end to end.


• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, replace the K9 body control module.




• If the test lamp is always ON


1. Ignition OFF, disconnect the X7 harness connector at the K9 body control module, ignition ON.
2. Test for less than 1 V between the control circuit terminal and ground.


• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K9 body control module.




• If the test lamp turns ON and OFF


5. Verify the scan tool Dome Lamp Switch parameter is Inactive.


• If Active


1. Ignition OFF, disconnect the X7 harness connector at the K9 body control module.
2. Test for infinite resistance between the signal circuit terminal 5 and ground.


• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K9 body control module.




• If Inactive


6. Install a 3 A fused jumper wire between the signal circuit terminal 5 and the ground circuit terminal 6.
7. Verify the scan tool Dome Lamp Switch parameter is Active.


• If not Active


1. Ignition OFF, disconnect the X7 harness connector at the K9 body control module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.


• If 1 V or greater, repair the short to voltage on the circuit.



• If less than 1 V


3. Test for less than 2 Ω in the signal circuit end to end.


• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, replace the K9 body control module.




• If Active


8. Test or replace the inoperative E37A dome/reading lamps.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Dome Lamp Bulb Replacement
• Courtesy Lamp Replacement
• Control Module References for BCM replacement, programming, and setup