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.

Circuit/System Description

The TRN/HAZRD FRT and TRN/HAZRD REAR fuses in the underhood fuse block supplies battery positive voltage to the body control module (BCM). When the turn signal switch is placed in either the left or right position, a signal is sent to the BCM to illuminate the desired turn signal lamps. The BCM has an internal flasher that sends an ON-OFF voltage signal to either the left or right turn signals and their instrument panel cluster (IPC) indicator.

Reference Information
Schematic Reference

Exterior Lights Schematics (Exterior Lights Diagrams)
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 respective 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 Circuit Malfunction.

2. Ignition ON, operate the left and right turn signals from the multifunction/turn signal 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 Circuit Test.

Circuit/System Testing

Turn Signal Lamp Circuit Malfunction
1. Ignition OFF, disconnect the harness connector at the affected turn signal bulb.
2. Verify that a test lamp illuminates when connected from battery voltage to the ground circuit terminal G.

• If the test lamp does not illuminate test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit terminal A and the ground circuit terminal G.
4. Ignition ON, operate the right turn signal and verify that the test lamp flashes.

• 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.

Turn Signal Switch Circuit Test
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 battery voltage 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 an open/high resistance or short to ground. If the circuit tests normal, replace the BCM.

4. If all circuits test normal, test or replace the turn signal/multifunction switch.

Component Testing

Turn Signal Switch Test
1. Ignition OFF, disconnect the harness connector X204 at the turn signal/multifunction switch.
2. Test for infinite resistance between the signal terminal B5 and the ground terminal B9 with the switch in the neutral position.

• If not the specified value, replace the turn signal/multifunction switch.

3. Test for 1k ohm between the signal terminal B5 and the ground terminal B9 with the switch in the right turn position.

• If not the specified value, replace the turn signal/multifunction switch.

4. Test for 3.5k ohms between the signal terminal B5 and the ground terminal B9 with the switch in the left turn position.

• If not the specified value, replace the turn signal/multifunction switch.

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