The INT 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 door open 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 courtesy lamp supply voltage circuit, providing battery voltage to the dome lamp and instrument panel (I/P) courtesy lamps. The courtesy lamps can be manually activated by placing the interior lamp switch in the DOME position. For more detailed information concerning courtesy lamp operation refer to Interior Lighting Systems Description and Operation.

Inadvertent power courtesy lamp feature provides a similar function for the interior lamps as a retained accessory power feature. The BCM will energize the courtesy lamps supply voltage circuit when the BCM is in the active state (awake). When the inadvertent power courtesy lamps supply voltage circuit is energized, it supplies voltage to all the interior lights listed below. The BCM will continue to supply voltage to the interior lamps after the ignition is turned OFF so that the interior lamps may be operated.

In the event that any of these lamps were to remain illuminated for a period of more than 20 minutes with the ignition switch in the OFF position and no BCM input activity, the BCM will deactivate the inadvertent power supply voltage circuit to prevent a total battery discharge condition.

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

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the scan tool Driver Door Open Sw. parameter while opening and closing the driver door. The parameter should change between Open and Closed.

⇒	If the parameter does not change between Open and Closed, refer to Door Open Switch Malfunction -- Driver.

2. Observe the scan tool Passenger Door Open Sw. parameter while opening and closing the front passenger door. The parameter should change between Open and Closed.

⇒	If the parameter does not change between Open and Closed, refer to Door Open Switch Malfunction -- Passenger.

3. Observe the scan tool Passenger Door Open Sw. parameter while opening and closing the left and right rear passenger doors. The parameter should change between Open and Closed.

⇒	If the parameter does not change between Open and Closed, refer to Door Open Switch Malfunction-- Passenger.

4. Ignition ON and all doors closed, observe the scan tool Ctsy. Lamp Actv. Reason parameter while turning the dome lamp switch ON and OFF. The parameter should change between Off and Manual.

⇒	If the parameter does not change between Off and Manual, refer to Dome Lamp Switch Malfunction.

Door Open Switch Malfunction-- Driver

1. Ignition OFF, disconnect the harness connector at the driver door lock.
2. Verify that a test lamp illuminates between the appropriate ground circuit terminal listed below and B+.

•	Base Level terminal 6

•	Uplevel terminal 8

⇒	If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the scan tool Driver Door Open Sw. parameter is Closed.

⇒	If not the specified value, test the appropriate signal circuit terminal listed below for a short to ground. If the circuit tests normal, replace the BCM.

•	Base Level terminal 5

•	Uplevel terminal 7

4. Install a 3A fused jumper wire between the appropriate signal circuit terminal listed and ground. Verify the scan tool Driver Door Open Sw. parameter is Open.

•	Base Level terminal 5

•	Uplevel terminal 7

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

5. If all circuits test normal, test or replace the door lock.

Door Open Switch Malfunction -- Passenger

1. Ignition OFF, disconnect the (X1 for Coupe) harness connector at the inoperative passenger door lock.
2. Verify that a test lamp illuminates between the appropriate ground circuit terminal listed below and B+.

•	Front Passenger Door Lock terminal 3

•	Left Rear Door Lock terminal 6

•	Right Rear Door Lock terminal 3

⇒	If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the scan tool Passenger Door Open Sw. parameter is Closed.

⇒	If not the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the BCM.

4. Install a 3A fused jumper wire between the appropriate signal circuit terminal listed below and ground. Verify the scan tool Passenger Door Open Sw. parameter is Open.

•	Front Passenger Door Lock terminal 2

•	Left Rear Door Lock terminal 5

•	Right Rear Door Lock terminal 2

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

5. If all circuits test normal, test or replace the appropriate door lock.

Dome Lamp Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Verify that a test lamp illuminates between the ground circuit terminal 8 and B+.

⇒	If the test lamp does not illuminate, test the ground circuit for an open/high resistance. If the circuit tests normal.

3. Ignition ON, verify the scan tool Ctsy. Lamp Actv. Reason parameter is OFF.

⇒	If not the specified value, test the signal circuit terminal 12 for a short to ground. If the circuit tests normal, replace the BCM.

4. Install a 3A fused jumper wire between the signal circuit terminal 12 and ground. Verify the scan tool Ctsy. Lamp Actv. Reason parameter is Manual.

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

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

Dome Lamp Malfunction

1. Ignition OFF, disconnect the harness connector at the dome lamp.
2. Verify that a test lamp illuminates between the ground circuit terminal B and B+.

⇒	If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit terminal A and ground.
4. Command the Courtesy Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	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, test or replace the dome lamp.

I/P Courtesy Lamp Malfunction

1. Ignition OFF, disconnect the harness connector at the I/P courtesy lamp.
2. Verify that a test lamp illuminates between the ground circuit terminal B and B+.

⇒	If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

3. Door Open, verify that a test lamp illuminates between the control circuit terminal A and ground.

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

4. If all circuits test normal, replace the inoperative I/P courtesy lamp.

Inadvertent Power Courtesy Lamps Malfunction

1. Ignition OFF, disconnect the X3 harness connector at the BCM.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 2 and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

3. Ignition OFF, connect the X3 harness connector at the BCM and disconnect the harness connector at the inoperative lamp.
4. Verify that a test lamp illuminates between the appropriate ground circuit terminal listed below and B+.

•	Dome/Reading Lamp terminal B

•	Left or Right Vanity Mirror terminal B

•	Reading Lamp Assembly terminal B with 9C1 or 9C3

•	Inside Rearview Mirror terminal 7 w/o UE1

•	Inside Rearview Mirror terminal 8 with UE1

•	Rear Compartment Courtesy Lamp terminal B

⇒	If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

5. Ignition ON, verify that a test lamp illuminates between the appropriate inadvertent power courtesy lamp circuit terminal listed below and ground.

•	Dome/Reading Lamp terminal B

•	Left or Right Vanity Mirror terminal B

•	Reading Lamp Assembly terminal A with 9C1 or 9C3

•	Inside Rearview Mirror terminal 2 w/o UE1

•	Inside Rearview Mirror terminal 6 with UE1

•	Rear Compartment Courtesy Lamp terminal A

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

6. If all circuits test normal, test or replace the inoperative lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.