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
With the ignition switch in the RUN position, the turn signal lamps will illuminate when the driver places the turn signal switch in the right or left positions. The instrument panel module (IPM) monitors the signal circuit of the turn signal/multifunction switch. The IPM relays the turn signal switch status to the rear integration module (RIM) via serial data. The RIM uses the status of the turn signal switch to command the turn signals ON and OFF. The RIM controls both front and rear turn signals. The IPM also sends a serial data message to the instrument panel cluster (IPC) to enable the turn signal indicators located in the IPC ON and OFF depending on the position of the turn signal switch. Voltage is supplied to the front and rear turn signals by the RIM. Ground is provided to the front turn signals at G104. The rear turn signals are grounded at G401 and G402. The turn signal/multifunction switch is grounded at G200.
Diagnostic Aids
The tail lamp outage detection circuits are low current B+ circuits supplied by the BCM. For purposes of testing, a test lamp connected between the outage detection circuit and ground will not illuminate due to the low current.
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 and Left Turn/Hazard Lamp Command parameters while cycling the turn signal switch between the left and right positions. The parameters should change between ON and OFF.
• If the parameters do not change between the commanded 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. Verify the turn signal lamps turn ON and OFF.
• If the turn signal lamps do not cycle between the selected states, refer to Turn Signal Lamps Malfunction.
3. Ignition ON, observe the left and right turn signal lamps and turn signal indicators on the IPC while activating the left and right turn signals. The left and right turn signal lamps and indicators should illuminate and flash 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.
4. 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 rear integration module.
• 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/multifunction switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal G.
• If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Left Front Turn/Hazard Command parameter is Off.
• If not the specified value, test the signal circuit terminal F for a short to ground. If the circuit tests normal, replace the IPM.
4. Verify the scan tool Right Front Turn/Hazard Command parameter is Off.
• If not the specified value, test the signal circuit terminal H for a short to ground. If the circuit tests normal, replace the IPM.
5. Install a 3 A fused jumper wire between the signal circuit terminal F and ground. Verify the scan tool Left Front Turn/Hazard Command parameter is On.
• 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 IPM.
6. Install a 3 A fused jumper wire between the signal circuit terminal H and ground. Verify the scan tool Right Front Turn/Hazard Command parameter is On.
• 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 IPM.
7. If all circuits test normal, test or replace the turn signal/multifunction switch.
Turn Signal Lamps Malfunction
1. Ignition OFF, disconnect the harness connector at the inoperative turn signal/repeater lamp.
2. Ignition OFF, exterior lamps OFF, test for less than 5 ohm between the ground circuit 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 and the ground circuit.
4. Command the appropriate turn signal lamp ON and OFF with the turn signal/multifunction switch. 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 RIM.
• 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 RIM.
5. If all circuits test normal, test or replace the appropriate turn signal lamp assembly.
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 outage detection circuit terminal C and ground.
• If the measured voltage is less than B+, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the RIM.
3. Ignition ON, connect a test lamp between the outage detection circuit terminal C 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 RIM.
4. If all circuits test normal, test or replace the tail lamp assembly.
Component Testing
Tail Lamp Assembly
1. Ignition OFF, disconnect the harness connector at the appropriate rear tail lamp assembly.
2. Test for infinite resistance between the outage detection terminal C and the ground terminal D at the tail lamp assembly.
• If not the specified value, replace the tail lamp assembly.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Front Parking and Turn Signal and Fog Lamp Assembly Replacement (STS) (Front Parking and Turn Signal and Fog Lamp Assembly Replacement (STS))
* Turn Signal Multifunction Switch Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for IPC or IPM replacement, setup, and programming