Voltage for the courtesy lamps is supplied from body control module (BCM), driver door switch, and passenger door switch. When a door is opened, a signal is applied to the door module. The door module then applies a message on the low speed GMLAN serial data communication circuit to the BCM to activate the courtesy lamps. The BCM then applies voltage to the courtesy lamps voltage supply circuit and the components on that circuit.

Schematic Reference

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 Courtesy Lamps output control ON and OFF with the scan tool. The interior courtesy lamps should turn ON and OFF.

⇒	If one or more of the courtesy lamps are always ON or always OFF refer to the Courtesy Lamp Malfunction.

2. Observe the scan tool Driver Door Switch, Driver Door Open Sw. parameter while opening and closing the driver door. The reading should change between Active and Inactive.

⇒	If the Driver Door Open Sw. parameter does not change between Active and Inactive, refer to Door Open Switch Malfunction-Front.

3. Observe the scan tool Passenger Door Switch, Passenger Door Open Sw. parameter while opening and closing the front passenger door. The reading should change between Active and Inactive.

⇒	If the Passenger Door Open Sw. parameter does not change between Active and Inactive, refer to Door Open Switch Malfunction-Front.

4. Observe the scan tool BCM Ctsy. Lamp Actv. Reason parameter while opening and closing each rear doors one at a time. The reading should change between Door Open and Door Closed

⇒	If the Ctsy. Lamp Actv. Reason parameter does not change between Door Open and Door Closed, refer to Door Open Switch Malfunction-Rear.

5. Ignition ON and all doors closed, observe the scan tool BCM 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/Interior Lamp Switch Malfunction.

6. Ignition ON and all doors closed, observe the scan tool BCM Ctsy. Lamp Actv. Reason parameter while turning the interior lamp defeat switch ON and OFF. The reading should change between Off and Manual Defeat.

⇒	If the Ctsy. Lamp Actv. Reason parameter does not change between Off and Manual, refer to Dome/Interior Lamp Switch Malfunction.

7. Ignition ON, command the Puddle/Courtesy Lamp ON and OFF with a scan tool. Verify the exterior illumination lamps turn ON and OFF.

⇒	If the exterior illumination lamps do not change between ON and OFF, refer to Exterior Illumination Lamps Malfunction Test.

8. Ignition ON, turn the reading lamps ON and OFF. The reading lamps should turn ON and OFF.

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

9. Ignition On, fold down the sun visors and verify the vanity lamps illuminate.

⇒	If the vanity lamps do not change between ON and OFF, refer to Vanity Mirrors Malfunction Test.

Courtesy Lamp Malfunction

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

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

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

•	Courtesy/Reading Lamp terminal C

•	Dome/Reading Lamp terminal A

•	Sunshade Lamps terminal A

•	Dome Lamp terminal A

•	Cargo Lamp terminal A

4. Ignition ON, command the Courtesy Lamps output control ON and OFF with the scan tool. The test lamp should turn ON and OFF.

⇒	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 appropriate bulb.

Door Open Switch Malfunction - Front

1. Ignition OFF, disconnect the harness connector at the inoperative door latch assembly.
2. Test for less than 10.0 ohms between the appropriate ground circuit terminal listed below and ground.

•	Drivers Door terminal 8

•	Passenger Door terminal 3

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

3. Ignition ON, verify the scan tool Door Open Switch parameter is CLOSED.

⇒	If the scan tool displays OPEN, test the appropriate signal circuit terminal listed below for a short to ground. If the circuit tests normal, replace the Door Lock/Window Switch.

•	Drivers Door terminal 7

•	Passenger Door terminal 2

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

•	Drivers Door terminal 7 to terminal 8

•	Passenger Door terminal 2 to terminal 3

⇒	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 Door Lock/Window Switch.

5. If all circuits test normal, replace the inoperative door latch assembly.

Door Open Switch Malfunction - Rear

1. Ignition OFF, disconnect the harness connector at the inoperative rear door latch assembly.
2. Interior lamps OFF, test for less than 10.0 ohms between the appropriate ground circuit terminal listed below and ground.

•	Left rear door latch assembly ground circuit terminal 6

•	Right rear door latch assembly ground circuit terminal 3

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

3. Ignition ON, verify a test lamp illuminates between the appropriate door open switch signal circuit terminal listed below and ground.

•	Left rear door open switch signal circuit terminal 5

•	Right rear door open switch signal circuit terminal 2

⇒	If the test lamp does not illuminate, test the signal circuit for a short to ground or an open/high resistance. 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 courtesy lamps illuminate and remain illuminated.

•	Left rear door open switch signal circuit terminal 5

•	Right rear door open switch signal circuit terminal 2

⇒	If the courtesy lamps do not remain illuminated, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, replace the inoperative rear door latch assembly.

Dome/Interior Lamp Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
2. Test for less than 5.0 ohms between the ground circuit terminal 8 and ground.

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

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

⇒	If the parameter is Manual or Manual Defeat, test the appropriate signal circuit terminal for a short to ground. If the circuit tests normal, replace the BCM.

•	Manual terminal 12

•	Manual Defeat terminal 9

4. Install a 3A fused jumper wire between the signal circuit terminal 12 and the ground circuit terminal 8. 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. Install a 3A fused jumper wire between the signal circuit terminal 9 and the ground circuit terminal 8. Verify the scan tool Ctsy. Lamp Actv. Reason parameter is Manual Defeat.

⇒	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.

6. If all circuits test normal, test or replace the headlamp and panel dimmer switch.

Outside Rearview Mirror Illumination Malfunction

1. Disconnect the harness connector at the appropriate exterior illumination lamp bulb.
2. Ignition ON, verify that a test lamp illuminates between the exterior illumination lamp supply circuit terminal and ground.

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

3. Connect a test lamp between the low side control circuit terminal and the exterior illumination lamp supply circuit terminal.
4. Command the Puddle/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 ground. If the circuit tests normal, replace the inoperative door switch.

⇒	If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the inoperative door switch.

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

Reading Lamps Malfunction

1. Ignition OFF, disconnect the X3 harness connector at the BCM.
2. Verify a test lamp illuminates between the IS LPS fuse 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. Reconnect the X3 harness connector at the BCM.
4. Disconnect the harness connector at the inoperative courtesy/reading lamp assembly.
5. Scan tool OFF, doors CLOSED, interior lamps OFF, test for less than 5.0 ohms between the listed ground circuit terminal below and ground.
6. Verify a test lamp illuminates between the control circuit terminal C and ground.

•	Courtesy/Reading Lamp terminal C

•	Dome/Reading 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.

7. Remove the IS LPS fuse and verify the test lamp turns OFF.

⇒	If the test lamp remains illuminated, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.

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

Vanity Mirrors Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate vanity mirror lamp.
2. Test for less than 5.0 ohms 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 inadvertent power supply circuit terminal A and ground.

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

4. Connect the harness connector at the vanity mirror lamp.
5. Remove the IS LPS fuse and verify the test lamp turns OFF.

⇒	If the test lamp remains illuminated, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.