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 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 1-2 Shift Solenoid (SS) Valve (MN5)
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 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. 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. 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
Turn Signal Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the turn signal/multifunction switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the appropriate ground circuit terminal listed below.
* Ground terminal F - with LE5 and MH2
* Ground terminal M - without LE5 and MH2
• If the test lamp does not illuminate, 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 appropriate signal circuit terminal listed below for a short to ground. If the circuit tests normal, replace the BCM.
* Signal terminal D - with LE5 and MH2
* Signal terminal K - without LE5 and MH2
4. Verify the scan tool Right Turn Signal Switch parameter is Inactive.
• If not the specified value, test the appropriate signal circuit terminal listed below for a short to ground. If the circuit tests normal, replace the BCM.
* Signal terminal E - with LE5 and MH2
* Signal terminal L - without LE5 and MH2
5. Install a 3 A fused jumper wire between the appropriate signal circuit terminal listed below and ground. Verify the scan tool Left Turn Signal Switch parameter is Active.
* Signal terminal D - with LE5 and MH2
* Signal terminal K - without LE5 and MH2
• 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 appropriate signal circuit terminal listed below and ground. Verify the scan tool Right Turn Signal Switch parameter is Active.
* Signal terminal E - with LE5 and MH2
* Signal terminal L - without LE5 and MH2
• 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. Verify that a test lamp illuminates between the B+ circuit terminal 1 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
3. Verify that a test lamp illuminates between the B+ circuit terminal 3 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Ignition OFF, connect the X4 harness connector at the BCM.
5. Disconnect the harness connector at the appropriate turn signal lamp.
6. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the appropriate ground circuit terminal listed below and ground.
* Left front turn signal ground terminal 1
* Right front turn signal ground terminal 1
* Left rear turn signal ground terminal B
* Right rear turn signal ground terminal B
* Left repeater ground terminal B
* Right repeater ground terminal B
• If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect a test lamp between the appropriate control circuit terminal listed below and ground.
* Left front turn signal control terminal 3
* Right front turn signal control terminal 3
* Left rear turn signal control terminal H
* Right rear turn signal control terminal H
* Left repeater control terminal A
* Right repeater control terminal A
8. Command the appropriate Turn Signal Lamp 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.
9. If all circuits test normal, replace the turn signal lamp assembly.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Tail Lamp Replacement Service and Repair
* Parking and Turn Signal Lamp Bulb Replacement Service and Repair
* Tail Lamp Bulb Replacement (Back Up and Turn Signal) Service and RepairTail Lamp Bulb Replacement (Stop Lamp) Service and Repair
* Turn Signal Multifunction Switch Replacement Turn Signal Multifunction Switch Replacement
* Front Side Turn Signal Lamp Replacement Service and Repair
* Control Module References Programming and Relearning for BCM or IPC replacement, setup, and programming