The body control module (BCM) applies battery voltage to the courtesy lamps through the courtesy lamps high control circuit. When any door is opened, the door ajar 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 high control circuit, providing battery voltage to all of the dome lamps, reading lamps, rear compartment lamp, and vanity mirror lamps. In the event that any of these lamps were to remain illuminated for more than 20 minutes with the ignition switch in the OFF position, the BCM will deactivate the courtesy lamp high control circuit to prevent a total battery discharge condition.

The center console flood lamp and the front driver and passenger door handle backlighting is supplied with voltage via the park lamp relay. When the headlamp switch is placed in either the HEAD or PARK position, ground is applied to the park lamp signal circuit to the body control module (BCM). The BCM responds by applying ground to the park lamp relay control circuit. This energizes the park lamp relay coil causing the relay switch contacts to close allowing battery voltage to flow to all of the park, tail, license, marker lamps , and interior ambient lighting.

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, command the Parking Lamps ON and OFF with a scan tool. The park lamps, center console flood lamp, and the front driver and passenger door handle backlighting should turn ON and OFF when changing between the commanded states.

⇒	If the park lamps do not illuminate when commanded, refer to Park Lamps Malfunction.

⇒	If the park lamps illuminate and the interior ambient lamps do not illuminate, refer to Center Console Flood/Door Handle Lamps Malfunction.

2. Observe the scan tool Driver Door Ajar Sw. parameter while opening and closing the driver door. The parameter should change between Door Closed and Door Ajar.

⇒	If the parameter does not change as the driver door is opened and closed, refer to Door Ajar Indicator Malfunction.

3. Observe the scan tool Door Ajar Switch parameter while opening and closing the front passenger and each rear door one at a time. The parameter should change between Door Closed and Door Ajar.

⇒	If the parameter does not change as each door is opened and closed , refer to Door Ajar Indicator Malfunction.

4. Observe the scan tool Trunk Ajar Switch parameter while opening and closing the rear compartment lid. The parameter should change between Trunk Closed and Trunk Ajar.

⇒	If the parameter does not change as the rear compartment is opened and closed, refer to Trunk Ajar Indicator Malfunction.

5. Command the Interior Lamps ON and OFF with a scan tool. The overhead courtesy lamps should turn ON and OFF when changing between the commanded states.

⇒	If the courtesy lamps do not illuminate when commanded, refer to Overhead Illuminated Entry Lamps Malfunction.

6. Rear compartment OPEN, command the Inadvertent Power ON and OFF with a scan tool. The rear compartment lamp should turn ON and OFF when changing between the commanded states.

⇒	If the rear compartment lamp does not illuminate when commanded, refer to Rear Compartment Lamp Malfunction.

7. Turn the front and rear reading lamps ON and OFF. The lamps should turn ON and OFF when activated.

⇒	If the reading lamps do not turn ON and OFF, refer to Reading Lamps Malfunction.

Overhead Illuminated Entry Lamps Malfunction

1. Ignition OFF, disconnect the harness connector at the inoperative courtesy/reading lamp assembly.
2. Ignition OFF, test for less than 1 ohm between the appropriate ground circuit terminal listed below and ground.

•	Dome/reading lamps control terminal A

•	Overhead console courtesy lamp control terminal A

•	Vanity mirror lamp - left control terminal B

•	Vanity mirror lamp - right control terminal B

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

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

•	Dome/reading lamps control terminal D

•	Overhead console courtesy lamp control terminal B

•	Vanity mirror lamp - left control terminal A

•	Vanity mirror lamp - right control terminal A

4. Command the Interior Lamps 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 OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

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

5. Ignition OFF, connect the harness connector at the inoperative courtesy/reading lamp assembly.
6. Disconnect the harness connector at the dome/reading lamp.
7. Connect a test lamp between the control circuit terminal D and the control circuit terminal B.
8. Command the Interior Lamps 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 OFF, test the control circuit terminal B for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

⇒	If the test lamp is always ON, test the control circuit terminal B for a short to ground. If the circuit tests normal, replace the BCM.

9. Ignition OFF, connect the harness connector at the inoperative courtesy/reading lamp assembly.
10. Disconnect the harness connector at the front courtesy lamp.
11. Connect a test lamp between the control circuit terminal B and the control circuit terminal C.
12. Center dome/reading lamp switch in the DOOR position, command the Interior Lamps 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 OFF, test the control circuit terminal C for a short to voltage or an open/high resistance. If the circuit tests normal, replace the center dome/reading lamp.

⇒	If the test lamp is always ON, test the control circuit terminal C for a short to ground. If the circuit tests normal, replace the center dome/reading lamp.

13. If all circuits test normal, replace the inoperative courtesy/reading lamp assembly.

Center Console Flood/Door Handle Lamps Malfunction

1. Ignition OFF, disconnect the harness connector at the dome/reading lamp.
2. Ignition OFF, test for less than 1 ohm between the ground circuit terminal B and ground.

⇒	If greater than the specified value, 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 Parking Lamps 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 OFF, test the control circuit for a short to ground or an open/high resistance.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage.

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

Reading Lamps Malfunction

1. Ignition OFF, disconnect the harness connector at the inoperative courtesy/reading lamp assembly.
2. Ignition OFF, test for less than 1 ohm between the ground circuit terminal A and ground.

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

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

•	Dome/reading lamps control terminal D - without C3Y

•	Overhead console courtesy/reading lamp control terminal B

4. Command the Inadvertent Power 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 OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

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

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

Rear Compartment Lamp Malfunction

1. Ignition OFF, disconnect the harness connector at the rear compartment lamp.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the control circuit terminal B.

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

3. Ignition ON, verify that a test lamp illuminates between the control circuit terminal C 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 rear compartment courtesy lamp.

Vanity Mirror Lamps Malfunction

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

⇒	If greater than the specified value, 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 Interior Lamps 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 OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

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

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.