The CTSY/LAMP 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 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 exterior courtesy lamps. For more detailed information concerning courtesy lamp operation refer to Interior Lighting Systems Description and Operation .

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 dome lamp switch parameter while pressing and releasing the dome lamp switch. The reading should toggle between OFF and ON.

⇒	If the reading does not change between the commanded states, refer to Dome Lamp Switch Malfunction.

2. Observe the scan tool LF door open switch parameter located in Keyless/Remote Start Data while opening and closing the driver door. The reading should toggle between OPEN and CLOSED.

⇒	If the reading does not change between the commanded states, refer to Door Open Switch Malfunction.

3. Observe the scan tool RF door open switch parameter located in Keyless/Remote Start Data while opening and closing the passenger door. The reading should toggle between OPEN and CLOSED.

⇒	If the reading does not change between the commanded states, refer to Door Open Switch Malfunction.

Dome Lamp Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the I/P dimmer switch.
2. Test for less than 1.0 ohm of resistance between the ground circuit terminal 1 and ground.

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

3. Ignition ON, verify the scan tool dome lamp switch parameter is OFF.

⇒	If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the IPC.

4. Install a 3A fused jumper wire between the signal circuit terminal 3 and ground. Verify the scan tool dome lamp switch parameter is ON.

⇒	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 IPC.

5. If all circuits test normal, test or replace the I/P dimmer switch.

Door Open Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the inoperative door latch assembly.
2. Test for less than 1.0 ohm of resistance between the ground circuit and ground.

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

3. Ignition ON, verify the scan tool door open switch parameter is CLOSED.

⇒	If the scan tool displays OPEN, 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 signal circuit and ground. Verify the scan tool door open switch parameter is OPEN.

⇒	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 inoperative door latch assembly.

Instrument Panel (I/P) Compartment Lamp Malfunction

1. Ignition OFF, disconnect the harness connector at the I/P compartment lamp.
2. Test for less than 1.0 ohm of resistance between the ground circuit terminal B and ground.

⇒	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 courtesy lamp supply voltage circuit terminal A 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.

4. If all circuits test normal, replace the I/P compartment lamp switch.

Instrument Panel Courtesy Lamps Malfunction

1. Ignition OFF, disconnect the harness connector at the inoperative courtesy lamp.
2. Test for less than 1.0 ohm of resistance between the low control circuit terminal B and ground.

⇒	If greater than the specified range, test the low control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

3. Ignition ON, verify that a test lamp illuminates between the courtesy lamp supply voltage circuit terminal A 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.

4. Ignition OFF, connect a test lamp between the supply voltage circuit terminal A and the low control circuit terminal B.
5. Command the interior lamps ON with a scan tool. The test lamp should turn ON for 5 seconds and then turn OFF.

⇒	If the test lamp remains ON at all times, test the low control circuit for a short to ground. If the circuits test normal, replace the BCM.

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

Rear Compartment Courtesy Lamps Malfunction

1. Ignition OFF, disconnect the harness connector at the inoperative rear compartment lamp.
2. Open the rear compartment lid.
3. Test for less than 1.0 ohm of resistance between the ground circuit terminal B and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance, if the circuits test normal, replace the rear compartment lid latch or pull down actuator.

4. Ignition ON, verify that a test lamp illuminates between the courtesy lamp supply voltage circuit terminal A 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 inoperative rear compartment lamp.

Underhood Lamp Malfunction

1. Ignition OFF, disconnect the harness connector at the underhood lamp.
2. Test for less than 1.0 ohm of resistance between the ground circuit terminal B and ground.

⇒	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 courtesy lamp supply voltage circuit terminal A 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.

4. If all circuits test normal, replace the underhood lamp.

Vanity Mirror Lamps Malfunction

1. Ignition OFF, disconnect the harness connector at the inoperative vanity mirror.
2. Test for less than 1.0 ohm of resistance between the ground circuit terminal B and ground.

⇒	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 courtesy lamp supply voltage circuit terminal A 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.

4. If all circuits test normal, replace the inoperative vanity mirror.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.