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
Ground is applied at all times to the turn signal/multifunction switch. The turn signal lamps may only be activated with the ignition switch in the ON position. 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 either the left or right turn position, a ground is applied through the turn signal switch signal circuit to the BCM indicating a turn signal request. When the specific request is seen, the BCM then applies a pulsating voltage through the front and rear turn signal supply voltage circuits illuminating the turn signal lamps. At the same time, the BCM sends a serial date message requesting the door module to illuminate the outside rearview mirror turn signal (if equipped) by applying a low reference to the ground side of the mirror turn signal lamp.
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 (Connector End Views By Name)
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 readings should change between Active and Inactive.
• If the parameters do not change between the commanded states, refer to Turn Signal/Multifunction Switch Malfunction.
2. Observe the right and left turn signal lamps while cycling the turn signal switch between the right and left positions. The front and rear turn signal lamps should turn ON and OFF.
• If the front or rear turn signal lamps do not turn ON and OFF, refer to Turn Signal Lamps Malfunction.
3. Observe the right and left outside rearview mirror turn signal indicators while cycling the turn signal switch between the right and left positions. The right and left outside rearview mirror turn signal indicators should turn ON and OFF.
• If the outside rearview mirror turn signal indicators do not turn ON and OFF, refer to Outside Rearview Mirror Turn Signal Indicator Malfunction.
4. Observe the left and right turn signal lamps and turn signal indicators on the instrument panel while cycling the turn signal switch between the right and left positions. The left and right turn signal lamps and indicators should illuminate and flash at a normal rate when turned ON.
• If the left and right turn signal lamps and indictors illuminate but flash in a rapid manner, refer to Tail Lamp Outage Detection Malfunction.
5. Command the Display 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
Warning
The high intensity discharge system produces high voltage and current. To reduce the risk of severe shocks and burns:
* Never open the high intensity discharge system ballast or the arc tube assembly starter.
* Never probe between the high intensity discharge system ballast output connector and the arc tube assembly.
Turn Signal/Multifunction Switch Malfunction
1. Ignition OFF, disconnect the X3 harness connector at the turn signal/multifunction switch.
2. Test for less than 5 ohm between the ground circuit terminal G 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 F 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 H 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 F and the ground circuit terminal G. 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 H and the ground circuit terminal G. 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/multifunction switch.
Turn Signal Lamps Malfunction
1. Ignition OFF, disconnect the X4 harness connector at the BCM.
2. Ignition ON, verify a test lamp illuminates between the following B+ terminals and ground:
* B+ terminal 1
* B+ terminal 2
* B+ terminal 3
• If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. If the circuit fuse is open, test the B+ circuit and the respective turn signal circuits for a short to ground.
3. Ignition OFF, disconnect the harness connector at the inoperative turn signal lamp.
4. Test for less than 5 ohm between the appropriate ground circuit terminal listed below and ground:
* Front headlamp assembly terminal A
* Tail lamp assembly terminal C - All Countries Except Japan, Korea, Taiwan
* Tail lamp assembly terminal H - Japan, Korea, Taiwan Only
* Repeater lamp terminal B - Japan, Korea, Taiwan Only
• If greater than the specified range, test the ground circuit for an open/high resistance.
5. Connect a test lamp between the appropriate control circuit terminal listed below and the ground:
* Front headlamp assembly terminal C
* Rear tail lamp assembly terminal B - All Countries Except Japan, Korea, Taiwan
* Rear tail lamp assembly terminal G - Japan, Korea, Taiwan Only
* Repeater lamp terminal A - Japan, Korea, Taiwan Only
6. Ignition ON, command the inoperative 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.
7. If all circuits test normal, test or replace the appropriate turn signal bulb.
Outside Rearview Mirror Turn Signal Indicator Malfunction
1. Ignition OFF, disconnect the X1 harness connector at the inoperative outside rearview mirror.
2. Connect a test lamp between the low reference circuit terminal 2 and B+.
3. Ignition ON, command the appropriate LF or RF 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 low reference circuit for a short to ground. If the circuit tests normal, replace the door module.
• If the test lamp is always OFF, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the door module.
4. Connect a test lamp between the control circuit terminal 1 and ground.
5. Ignition ON, command the appropriate LF or RF 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 test lamp is always OFF, test the control circuit for an open/high resistance.
6. If all circuits test normal, test or replace the outside rearview mirror lamp bulb.
Tail Lamp Outage Detection Malfunction
1. Ignition OFF, disconnect the harness connector at the appropriate rear tail lamp assembly.
2. Ignition ON, test for B+ between the signal circuit terminal D and ground.
• If less than B+, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
3. Ignition ON, connect a test lamp between the signal circuit terminal D and ground. The test lamp should not illuminate.
• If the test lamp illuminates, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
4. If all circuits test normal, test or replace the tail lamp assembly.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Turn Signal Multifunction Switch Replacement (Service and Repair)
* Parking and Turn Signal Lamp Bulb Replacement (Service and Repair)
* Tail Lamp Replacement (Service and Repair)
* Parking and Turn Signal Lamp Bulb Replacement (Service and Repair)
* Control Module References (Programming and Relearning)for BCM or IPC replacement, setup, and programming