Turn Signal Lamps and/or Indicators Malfunction
Turn Signal Lamps and/or Indicators Malfunction
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
Ground is applied at all times at G106 to the turn signal/multifunction switch. The turn signal lamps may only be activated with the ignition switch in the ON or START position. When the turn signal/multifunction switch is placed in either the TURN RIGHT or TURN LEFT position, ground is applied to the body control module (BCM) through either the right turn or left turn signal switch signal circuit. The BCM then applies a pulsating voltage to the front and rear turn signal lamps through there respective voltage supply circuits. When a turn signal request is received by the BCM, a serial data message is sent to the instrument panel cluster (IPC) requesting the respective turn signal indicator be pulsed ON and OFF.
Reference Information
Schematic Reference
Exterior Lights Schematics (Exterior Lights Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Exterior Lighting Systems Description and Operation (Exterior Lighting Systems Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, command the following ON and OFF with a scan tool. The appropriate turn signal lamp should turn ON and OFF.
* LF Turn Signal
* LR Turn Signal
* RF Turn Signal
* RR Turn Signal
• If the turn signal lamp is always ON or does not turn ON, refer to Turn Signal Lamp Malfunction.
2. Ignition ON, operate the left and right turn signals from the turn signal/multifunction switch and verify the left and right turn signal lamps and indicators operate normal.
• If the left or right turn signals do not operate, refer to the Turn Signal Switch Malfunction.
Circuit/System Testing
Turn Signal Switch Malfunction
1. Ignition OFF, disconnect the harness connector X204 at the turn signal/multifunction switch.
2. Test for less than 5 ohms between the ground circuit terminal B9 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify B+ is present between the turn signal switch signal circuit terminal B5 and ground.
• If not the specified value, test the signal circuit terminal B5 for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
4. If all circuits test normal, test or replace the turn signal/multifunction switch.
Turn Signal Lamp Malfunction
1. Ignition OFF, disconnect the harness connector at the inoperative turn signal lamp.
2. Test for less than 5 ohms between the ground circuit terminal G and ground.
• If more than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit terminal A and ground.
4. Ignition ON, command the inoperative lamp ON and OFF with a 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 inoperative bulb.
Turn Signal Indicators Malfunction
Ignition ON, with a scan tool perform the Display Test for the instrument panel cluster (IPC) and observe the turn signal lamp indicators.
If the turn signal lamp indicators illuminate during the test, replace the BCM.
If the turn signal lamp indicators do not illuminate during the test or remain illuminated at all times, replace the IPC.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Park/Turn Signal/Side Marker Lamp Bulb Replacement (Service and Repair)
* Tail Lamp Bulb Replacement (Service and Repair)
* Turn Signal Multifunction Switch Replacement (Turn Signal Multifunction Switch Replacement)
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming