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
* Interior Lights Dimming Schematics Interior Lights Dimming Schematics
Connector End View Reference
Component Connector End Views Connector Views
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. Ignition ON, observe the scan tool Door Ajar Sw. parameter while opening and closing each vehicle door. The parameter should change between Door Ajar and Door Closed.
• If the parameter does not change between the selected states, refer to Door Ajar Indicator Malfunction Door Ajar Indicator Malfunction.
2. Observe the scan tool Rear Closure Ajar Sw. parameter while opening and closing the trunk. The parameter should change between Active and Inactive.
• If the parameter does not change between the selected states, refer to Liftgate Ajar Indicator Malfunction (RPO TB7) Liftgate Ajar Indicator Malfunction (RPO TB7) or Liftgate/Liftgate Window Ajar Indicator Malfunction (Manual Liftgate) Liftgate/Liftgate Window Ajar Indicator Malfunction (Manual Liftgate)Liftgate/Liftgate Window Ajar Indicator Malfunction (Power Liftgate) Liftgate/Liftgate Window Ajar Indicator Malfunction (Power Liftgate) ,
3. 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.
4. 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.
5. 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.
6. 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.
7. 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.
8. 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 lamp.
2. 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.
3. Connect a test lamp between the control circuit terminal listed below and the ground.
* Courtesy/Reading Lamp terminal A
* Dome/Reading Lamp terminal C
* Door Courtesy 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 courtesy lamp.
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 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 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 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 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 ohm between the ground circuit terminal B and ground.
6. Verify a test lamp illuminates between the control circuit terminal listed below 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 courtesy lamp assembly.
Vanity Mirror Lighting Malfunction
1. Ignition OFF, disconnect the harness connector at the appropriate vanity mirror lamp.
2. Test for less than 5.0 ohm between the ground circuit terminal B and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp illuminates between the control 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 vanity mirror.
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 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 lamp.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Dome Lamp Replacement Service and Repair
* Door Courtesy Lamp and Reflector Replacement Door Courtesy Lamp and Reflector Replacement
* Door Lock and Side Window Switch Replacement - Driver Side Door Lock and Side Window Switch Replacement - Driver Side
* Front Side Door Lock Replacement Front Side Door Lock Replacement
* Rear Side Door Lock Replacement Rear Side Door Lock Replacement
* Headlamp Switch Replacement (Cadillac) Service and RepairHeadlamp Switch Replacement (Except Cadillac) Service and Repair
* Control Module References Control Module References for BCM, driver door switch, or passenger door switch replacement, setup, and programming