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Courtesy Lamps Malfunction




Courtesy Lamps Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information





Circuit/System Description

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.

Reference Information
Schematic Reference

Interior Lights Schematics (Interior Lights Schematics)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Interior Lighting Systems Description and Operation (Interior Lighting Systems)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Control Module References) for scan tool information

Circuit/System Verification

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

• If the courtesy lamps do not turn ON and OFF when commanded, refer to Courtesy Lamp Malfunction.

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

• If the Driver Door Ajar 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 Ajar Sw. parameter while opening and closing the front passenger door. The reading should change between Active and Inactive.

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

4. Observe the scan tool Ctsy. Lamp Actv. Reason parameter while opening and closing each rear door 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. 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/Interior Lamp Switch Malfunction.

6. All doors closed, observe the scan tool 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. Turn the individual reading lamps ON and OFF with their respective switches. The reading lamps should turn ON and OFF when changing between the selected states.

• If any reading lamp does not turn ON and OFF when selected, refer to Reading Lamps Malfunction.

8. Turn the left and right vanity mirror lamps ON and OFF with their respective switches. The vanity mirror lamps should turn ON and OFF when changing between the selected states.

• If any reading lamp does not turn ON and OFF when selected, refer to Vanity Mirror Lighting Malfunction.

9. Command the 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 Outside Rearview Mirror Illumination Malfunction.

Circuit/System Testing

Courtesy Lamp Malfunction
1. Ignition OFF, disconnect the harness connector at the appropriate courtesy lamp.
2. Test for less than 5 ohm between the ground circuit terminal 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 and the ground circuit terminal.
4. Ignition ON, command the Courtesy Lamps 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, replace the courtesy lamp.

Door Open Switch Malfunction - Front w/AN3
1. Ignition OFF, disconnect the harness connector at the door latch assembly.
2. Test for less than 10.0 ohm between the ground circuit terminal listed below and ground.

* Driver door latch - terminal 8
* Passenger door latch - terminal 3

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

3. Ignition ON, verify the scan tool Door Ajar Switch parameter is INACTIVE.

• If the scan tool displays ACTIVE, test the signal circuit terminal listed below for a short to ground. If the circuit tests normal, replace the door control module.

* Driver door open switch - terminal 6
* Passenger door open switch - terminal 1

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

* Driver door open switch - terminal 6
* Passenger door open switch - terminal 1

• 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 control module.

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

Door Open Switch Malfunction - Front w/o AN3
1. Ignition OFF, disconnect the harness connector at the door latch assembly.
2. Test for less than 10.0 ohm between the ground circuit terminal listed below and ground.

* Terminal 8 (with AU3)
* Terminal 6 (without AU3)

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

3. Ignition ON, verify the scan tool Door Ajar Switch parameter is INACTIVE.

• If the scan tool displays ACTIVE, test the signal circuit terminal 9 for a short to ground. If the circuit tests normal, replace the BCM.

4. Install a 3 A fused jumper wire between signal circuit terminal 9 and ground. Verify the scan tool Door Ajar Switch parameter is ACTIVE.

• 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, replace the door latch assembly.

Door Open Switch Malfunction - Rear
1. Ignition OFF, disconnect the harness connector at the rear door latch assembly.
2. Interior lamps OFF, test for less than 10.0 ohm between the ground circuit terminal listed below and ground.

* Left rear door latch assembly - terminal 6
* Right rear door latch assembly - 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 door open switch signal circuit terminal listed below and ground.

* Left rear door open switch - terminal 4
* Right rear door open switch - terminal 1

• 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 3 A fused jumper wire between the signal circuit terminal listed below and ground. Verify the courtesy lamps illuminate and remain illuminated.

* Left rear door open switch - terminal 4
* Right rear door open switch - terminal 1

• 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 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 ohm 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 scan tool parameter is Manual or Manual Defeat, test the signal circuit terminal listed below for a short to ground. If the circuit tests normal, replace the BCM.

* Manual terminal 12
* Manual Defeat terminal 9

4. Install a 3 A 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 3 A 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.

Reading Lamps Malfunction
1. Ignition OFF, disconnect the X2 harness connector at the BCM.
2. Verify a test lamp illuminates between the IS LPS fuse B+ circuit terminal 1 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 X2 harness connector at the BCM.
4. Disconnect the harness connector at the appropriate courtesy/reading lamp assembly.
5. Scan tool OFF, doors CLOSED, interior lamps OFF, test for less than 5.0 ohm between the ground circuit terminal B and ground.

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

6. Verify 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.

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 courtesy/reading lamp assembly.

Vanity Mirror Lighting Malfunction
1. Ignition OFF, disconnect the harness connector at the appropriate vanity mirror lamp.
2. Test for less than 5 ohm 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 signal circuit terminal A and ground.

• 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. 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 vanity mirror lamp.

Outside Rearview Mirror Illumination Malfunction
1. Disconnect the harness connector at the appropriate exterior illumination lamp.
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 exterior illumination lamp.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Dome Lamp Replacement (Service and Repair)
* Outside Rearview Mirror Courtesy Lamp Replacement (Outside Rearview Mirror Courtesy Lamp Replacement)
* Headlamp Switch Replacement (with RPO SLT) (Headlamp Switch Replacement (with RPO SLT))Headlamp Switch Replacement (without RPO SLT) (Headlamp Switch Replacement (without RPO SLT))
* Control Module References (Control Module References) for BCM, driver door switch, or passenger door switch replacement, programming, and setup

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