Turn Signal Lamps and/or Indicators Malfunction
Turn Signal Lamps and/or Indicators 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
The body control module (BCM) controls the vehicle turn signals based on inputs from the turn signal/multifunction switch. With the turn signal/multifunction switch in the left turn position, a ground path is provided on the left turn signal switch signal circuit, indicating a left turn signal request. With the turn signal/multifunction switch in the right turn position, a ground path is provided on the right turn signal switch signal circuit, indicating a right turn signal request. When the specific request is seen, the BCM will pulse the respective turn signal lamp control circuits, illuminating the turn signal lamps.
When a turn signal request is seen by the BCM, a serial data message is sent to the instrument panel cluster (IPC) requesting the respective turn signal indicator be pulsed.
Reference Information
Schematic Reference
Exterior Lights Schematics Exterior Lights Schematics
Connector End View Reference
Component Connector End Views A/C Compressor Clutch
Description and Operation
Exterior Lighting Systems Description and Operation Exterior 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 Programming and Relearning for scan tool information
Circuit/System Verification
1. Ignition ON, observe the scan tool Right Turn Signal Switch and Left Turn Signal Switch parameters while cycling the turn signal switch between the right and left positions. The parameters should change between Active and Inactive when changing between the selected states.
• If the parameters do not change between the selected states, refer to Turn Signal Switch Malfunction.
2. Ignition ON, observe the right and left turn signal lamps while cycling the turn signal switch between the right and left positions. The turn signal lamps turn ON and OFF when changing between the selected states.
• If the turn signal lamps do not change between the selected states, refer to Turn Signal Lamps Malfunction.
3. Command the All Indicators Test ON and OFF with a scan tool. The left and right turn signal indicators should turn ON and OFF when changing between the commanded states.
• If the left and right turn signal indicators illuminate during the test, replace the BCM.
• If the left and right turn signal indicators do not illuminate during the test or remain illuminated at all times, replace the instrument cluster.
Circuit/System Testing
Turn Signal Switch Malfunction
1. Ignition OFF, disconnect the X1 harness connector at the turn signal/multi-function switch.
2. Test for less than 5 ohms between the ground circuit terminal 1 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Left Turn Signal Switch parameter is Inactive.
• If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the BCM.
4. Verify the scan tool Right Turn Signal Switch parameter is Inactive.
• If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the BCM.
5. Install a 3 A fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool Left Turn Signal 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.
6. Install a 3 A fused jumper wire between the signal circuit terminal 3 and ground. Verify the scan tool Right Turn Signal 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.
7. If all circuits test normal, test or replace the turn signal/multi-function switch.
Turn Signal Lamps Malfunction
1. Ignition OFF, disconnect the harness connector at the appropriate turn signal lamp.
2. Test for less than 5.0 ohms between the ground circuit terminal listed below and ground.
* Park/turn signal lamp - terminal B
* Turn signal lamp - front - terminal 2 (WDA)
* Turn signal lamp - front - terminal 1 (W49/Z88)
* Turn signal lamp - lower front - terminal 2
* Outside rearview mirror lamp - terminal 10
* Tail lamp - terminal D
* Tail/stop and turn signal lamp - terminal B
• 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 ground.
* Park/turn signal lamp - terminal A
* Turn signal lamp - front - terminal 1 (WDA)
* Turn signal lamp - front - terminal 2 (W49/Z88)
* Turn signal lamp - lower front - terminal 1
* Outside rearview mirror lamp - terminal 5
* Tail lamp - terminal E
* Tail/stop and turn signal lamp - terminal A
4. Command the appropriate Turn Signal 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 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 turn signal lamp.
Component Testing
Turn Signal/Multifunction Switch
1. Ignition OFF, disconnect the harness connector X1 at the turn signal/multifunction switch.
2. Test for infinite resistance between the following terminals and the ground circuit terminal 1 with the switch in the neutral position.
* Signal terminal 2
* Signal terminal 3
• If not the specified value, replace the turn signal/multifunction switch.
3. Test for less than 2.0 ohms between the signal circuit terminal 2 and the ground circuit terminal E with the switch in the left turn position.
• If greater than the specified range, replace the turn signal/multifunction switch.
4. Test for less than 2.0 ohms between the signal circuit terminal 3 and the ground circuit terminal E with the switch in the left turn position.
• If greater than the specified range, replace the turn signal/multifunction switch.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Turn Signal Multifunction Switch Replacement Turn Signal Multifunction Switch Replacement
* Headlamp Replacement (Acadia) Headlamp ReplacementHeadlamp Replacement (Traverse with TVP) Headlamp Replacement (Enclave) Headlamp Replacement
* Parking and Turn Signal Lamp Replacement (Traverse) Parking and Turn Signal Lamp Replacement
* Parking and Turn Signal Lamp Bulb Replacement (Acadia) Service and RepairParking and Turn Signal Lamp Bulb Replacement (Enclave) Service and RepairParking and Turn Signal Lamp Bulb Replacement (Traverse) Service and Repair
* Tail Lamp Replacement (Enclave) Service and RepairTail Lamp Replacement (Acadia) Service and RepairTail Lamp Replacement (Traverse) Service and Repair
* Tail Lamp Bulb Replacement (Acadia) Service and RepairTail Lamp Bulb Replacement (Traverse) Service and RepairTail Lamp Bulb Replacement (Enclave) Service and Repair
* Control Module References Programming and Relearning for BCM and IPC replacement, programming and setup