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

Lighting Systems Connector End Views

Electrical Information Reference

Scan Tool Reference

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

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

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

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

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

⇒	If the Passenger Door Open Sw. parameter does not change between Open and Closed, refer to Door Open Switch Circuit Test -- 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 reading should change between OFF and MANUAL.

⇒	If the Ctsy. Lamp Actv. Reason parameter does not change between OFF and MANUAL, refer to Dome Lamp Switch Circuit Test.

5. If all scan tool parameters test normal, refer to the appropriate circuit test listed below:

•	Dome Lamp Circuit Test

•	I/P Courtesy Lamp Circuit Test

•	Inadvertent Power Courtesy Lamps Circuit Test

Door Open Switch Circuit Test -- Driver

1. Ignition OFF, disconnect the (C1 for Coupe) harness connector at the driver door lock.
2. Test for less than 10 ohms of resistance between the appropriate ground circuit terminal listed below and ground.

•	Base Level Sedan terminal 6

•	Uplevel Sedan terminal 8

•	Coupe terminal D C1

⇒	If greater than the specified range, 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 Sedan terminal 5

•	Uplevel Sedan terminal 7

•	Coupe terminal C C1

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 Sedan terminal 5

•	Uplevel Sedan terminal 7

•	Coupe terminal C C1

⇒	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 Circuit Test -- Passenger

1. Ignition OFF, disconnect the (C1 for Coupe) harness connector at the inoperative passenger door lock.
2. Test for less than 10 ohms of resistance between the appropriate ground circuit terminal listed below and ground.

•	Sedan -- Front Passenger Door Lock terminal 3

•	Coupe -- Front Passenger Door Lock terminal A C1

•	Left Rear Door Lock terminal 6

•	Right Rear Door Lock terminal 3

⇒	If greater than the specified range, 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.

•	Sedan -- Front Passenger Door Lock terminal 2

•	Coupe -- Front Passenger Door Lock terminal B C1

•	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 Circuit Test

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 Circuit Test

1. Ignition OFF, disconnect the (C1 Sedan, C2 Coupe) harness connector at the dome lamp.
2. Ignition OFF, test for less than 5.0 ohms of resistance between the appropriate ground circuit terminal listed below and ground.

•	Sedan terminal B

•	Coupe terminal A C2

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

3. Connect a test lamp between the appropriate supply voltage circuit terminal listed below and ground.

•	Sedan terminal A

•	Coupe terminal A C1

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 supply voltage circuit for a short to voltage. If the circuit tests normal, replace the BCM.

⇒	If the test lamp is always OFF, 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, test or replace the dome lamp.

I/P Courtesy Lamp Circuit Test

1. Ignition OFF, disconnect the harness connector at the I/P courtesy lamp.
2. Test for less than 5.0 ohms of resistance between the ground circuit terminal B and ground.

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

3. Door Open, verify that a test lamp illuminates between the supply voltage circuit terminal A 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.

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

Inadvertent Power Courtesy Lamps Circuit Test

1. Ignition OFF, disconnect the harness connector at the inoperative lamp.
2. Test for less than 5.0 ohms of resistance between the appropriate ground circuit terminal listed below and ground.

•	Dome/Reading Lamp terminal B -- Sedan

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

3. 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 -- Sedan

•	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 inadvertent power courtesy lamp 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 lamp.

Door Open Switch Test

1. Ignition OFF, remove the appropriate door lock.
2. Test for infinite resistance between the appropriate signal and ground terminals listed below with the switch in the open position.

•	Driver door coupe -- signal terminal C and ground terminal D

•	Driver door base sedan -- signal terminal 5 and ground terminal 6

•	Driver door uplevel sedan -- signal terminal 7 and ground terminal 8

•	Front passenger coupe -- signal terminal B and ground terminal A

•	Front passenger sedan -- signal terminal 2 and ground terminal 3

•	Left rear door -- signal terminal 5 and ground terminal 6

•	Right rear door -- signal terminal 2 and ground terminal 3

⇒	If not the specified value, replace the appropriate door lock.

3. Test for less than 2 ohms between the appropriate signal and ground terminals listed below with the switch in the closed position.

•	Driver door coupe -- signal terminal C and ground terminal D

•	Driver door base sedan -- signal terminal 5 and ground terminal 6

•	Driver door uplevel sedan -- signal terminal 7 and ground terminal 8

•	Front passenger coupe -- signal terminal B and ground terminal A

•	Front passenger sedan -- signal terminal 2 and ground terminal 3

•	Left rear door -- signal terminal 5 and ground terminal 6

•	Right rear door -- signal terminal 2 and ground terminal 3

⇒	If greater than the specified range, replace the appropriate door lock.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.