Courtesy Lamps Malfunction (w/AN3)
Courtesy Lamps Malfunction (w/AN3)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* 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.
Circuit/System Verification
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 control circuit test.
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 Test-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 Test-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 Test-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 Test.
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 Test.
Circuit/System Testing
Courtesy Lamp Control Circuit Test
1. Ignition OFF, disconnect the harness connector at an affected lamp bulb.
2. Test for less than 1 ohm of resistance 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 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 bulb.
Door Open Switch Test-Front
1. Ignition OFF, disconnect the harness connector at the affected door latch.
2. Test for less than 1 ohm of resistance between the listed ground circuit terminal and ground.
* Driver terminal 8
* Passenger 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 open switch parameter is inactive.
^ If not the specified value, test the listed signal circuit terminal for a short to ground. If the circuit tests normal, replace the affected door switch.
* Driver terminal 7
* Passenger terminal 2
4. Install a 3A fused jumper wire between the listed signal circuit terminal and low reference circuit terminal. Verify the scan tool door open switch parameter is active.
* Driver terminal 7 to terminal 8
* Passenger 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 affected door switch.
5. If all circuits test normal, test or replace the affected door latch.
Door Open Switch Test-Rear
1. Ignition OFF, disconnect the harness connector at the affected door latch.
2. Test for less than 1 ohm of resistance between the listed ground circuit terminal and ground.
* Left terminal 6
* Right terminal 3
^ If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool passenger door open switch parameter is Closed.
^ If not the specified value, test the listed signal circuit terminal for a short to ground. If the circuit tests normal, replace the BCM.
* Left terminal 5
* Right terminal 2
4. Install a 3A fused jumper wire between the listed signal circuit terminal and low reference circuit terminal. Verify the scan tool passenger door open switch parameter is Open.
* Left terminal 5 to terminal 6
* Right 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 BCM.
5. If all circuits test normal, test or replace the affected door latch.
Dome/Interior Lamp Switch Test
1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Test for less than 1 ohm of resistance 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 not the parameter is Manual or Manual Defeat, test the affected 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 switch.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Dome Lamp Replacement
* Front Side Door Lock Replacement
* Rear Door Lock Replacement (Extended Cab Upper) Rear Door Lock Replacement (Crew Cab) Rear Door Lock Replacement (Extended Cab Lower)
* Headlamp Switch Replacement (without RPO SLT) Headlamp Switch Replacement (with RPO SLT)