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 vehicle mode switch in the SERVICE MODE or ON positions. 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 responds to the turn signal switch input by applying a pulsating voltage to the front and rear turn signal lamps through there respective control circuits. When a turn signal request is received by the BCM, a serial data message is sent to the instrument cluster requesting the respective turn signal indicator be pulsed ON and OFF.
Diagnostic Aids
The tail lamp outage detection circuits are low current B+ circuits that will not illuminate a test lamp.
Reference Information
Schematic Reference
* Exterior Lights Schematics Exterior Lights Schematics
* Body Control System Schematics [1][2]Body Control Systems
Connector End View Reference
Component Connector End Views Hybrid/EV Battery Pack X1
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. Vehicle in Service Mode.
2. Verify the scan tool Right Turn Signal Switch and Left Turn Signal Switch parameters change between Active and Inactive while cycling the turn signal switch between the right and left positions.
• If the parameters do not change
Refer to Turn Signal/Multifunction Switch Malfunction.
• If the parameters change
3. Verify the left front turn signal lamp turns ON and OFF while commanding the Left Front Turn Signal Lamp ON and OFF with a scan tool.
• If the left front turn signal lamp does not turn ON and OFF
Refer to Turn Signal Lamps Malfunction.
• If the left front turn signal lamp turns ON and OFF
4. Verify the right front turn signal lamp turns ON and OFF while commanding the Right Front Turn Signal Lamp ON and OFF with a scan tool.
• If the right front turn signal lamp does not turn ON and OFF
Refer to Turn Signal Lamps Malfunction.
• If the right front turn signal lamp turns ON and OFF
5. Verify the left rear turn signal lamp turns ON and OFF while commanding the Left Rear Turn Signal/Brake Lamp ON and OFF with a scan tool.
• If the left rear turn signal lamp does not turn ON and OFF
Refer to Turn Signal Lamps Malfunction.
• If the left rear turn signal lamp turns ON and OFF
6. Verify the right rear turn signal lamp turns ON and OFF while commanding the Right Rear Turn Signal/Brake Lamp ON and OFF with a scan tool.
• If the right rear turn signal lamp does not turn ON and OFF
Refer to Turn Signal Lamps Malfunction.
• If the right rear turn signal lamp turns ON and OFF
7. Verify all front and rear turn signal lamps and the turn signal indicators on the instrument cluster flash at a normal rate while activating the left and right turn signals.
• If all front and rear turn signal lamps and indictors illuminate but flash in a rapid manner
Refer to Tail Lamp Outage Detection Malfunction.
• If all front and rear turn signal lamps and indictors illuminate and flash at a normal rate
8. Verify the left and right turn signal indicators turn ON and OFF while commanding the Instrument Cluster Gauge Sweep Test ON and OFF with a scan tool.
• If the left or right turn signal indictors do not turn ON and OFF
Refer to Turn Signal Indicators Malfunction.
• If the left and right turn signal indictors turn ON and OFF
9. All OK.
Circuit/System Testing
Turn Signal/Multifunction Switch Malfunction
1. Vehicle OFF, scan tool disconnected, all doors closed, all accessories OFF, disconnect the harness connector at the S78 turn signal/multifunction switch. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 ohms between the ground circuit terminal 6 and ground.
• If 10 ohms or greater
1. Vehicle OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 10 ohms
3. Vehicle in Service Mode.
4. Verify the scan tool Left Turn Signal Switch parameter is Inactive.
• If not Inactive
1. Vehicle OFF, disconnect the X3 harness connector at the K9 body control module.
2. Test for infinite resistance between the signal circuit terminal 5 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K9 body control module.
• If Inactive
5. Install a 3 A fused jumper wire between the signal circuit terminal 5 and the ground circuit terminal 6.
6. Verify the scan tool Left Turn Signal Switch parameter is Active.
• If not Active
1. Vehicle OFF, disconnect the X3 harness connector at the K9 body control module, vehicle in Service Mode.
2. Test for less than 1 V between the signal circuit terminal 5 and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V
3. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K9 body control module.
• If Active
7. Verify the scan tool Right Turn Signal Switch parameter is Inactive.
• If not Inactive
1. Vehicle OFF, disconnect the X3 harness connector at the K9 body control module.
2. Test for infinite resistance between the signal circuit terminal 4 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K9 body control module.
• If Inactive
8. Install a 3 A fused jumper wire between the signal circuit terminal 4 and the ground circuit terminal 6.
9. Verify the scan tool Right Turn Signal Switch parameter is Active.
• If not Active
1. Vehicle OFF, disconnect the X3 harness connector at the K9 body control module, vehicle in Service Mode.
2. Test for less than 1 V between the signal circuit terminal 4 and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V
3. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K9 body control module.
• If Active
10. Test or replace the S78 turn signal/multifunction switch.
Turn Signal Lamps Malfunction
1. Vehicle OFF, exterior lamps OFF, disconnect the harness connector at the appropriate E4 turn signal lamp.
2. Test for less than 5 ohms between the appropriate ground circuit terminal listed below and ground.
* E4N park/turn signal lamp - left terminal 1
* E4Y turn signal repeater lamp - left terminal 2
* E4P park/turn signal lamp - right terminal 1
* E4Z turn signal repeater lamp - right terminal 2
* E42L tail lamp assembly - left terminal 4
* E42R tail lamp assembly - right terminal 4
• If 5 ohms or greater
1. Vehicle OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 5 ohms
3. Connect a test lamp between the appropriate control circuit terminal listed below and ground.
* E4N park/turn signal lamp - left terminal 3
* E4Y turn signal repeater lamp - left terminal 1
* E4P park/turn signal lamp - right terminal 3
* E4Z turn signal repeater lamp - right terminal 1
* E42L tail lamp assembly - left terminal 1
* E42R tail lamp assembly - right terminal 1
4. Verify the test lamp turns ON and OFF when commanding the appropriate Turn Signal Lamp ON and OFF with a scan tool.
• If the test lamp is always OFF
1. Vehicle OFF, disconnect the appropriate harness connector listed below at the K9 body control module.
* X5 left turn signals
* X4 right turn signals
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K9 body control module.
• If the test lamp is always ON
1. Vehicle OFF, disconnect the appropriate harness connector listed below at the K9 body control module, vehicle in Service Mode.
* X5 left turn signals
* X4 right turn signals
2. Test for less than 1 V between the control circuit terminal and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K9 body control module.
• If the test lamp turns ON and OFF
5. Test or replace the appropriate E4 turn signal lamp.
Tail Lamp Outage Detection Malfunction
1. Vehicle OFF, disconnect the harness connector at the appropriate E42 tail lamp assembly, vehicle in Service Mode.
2. Test for B+ between the signal circuit terminal 3 and ground.
• If less than B+
1. Vehicle OFF, disconnect the appropriate harness connector listed below at the K9 body control module.
* X6 left tail lamp
* X7 right tail lamp
2. Test for infinite resistance between the signal circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K9 body control module.
• If B+
3. Verify a test lamp does not illuminate between the signal circuit terminal 3 and ground.
• If the test lamp illuminates
1. Vehicle OFF, disconnect the appropriate harness connector listed below at the K9 body control module, vehicle in Service Mode.
* X6 left tail lamp
* X7 right tail lamp
2. Test for less than 1 V between the signal circuit terminal and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K9 body control module.
• If the test lamp does not illuminate
4. Test or replace the appropriate E42 tail lamp assembly.
Turn Signal Indicators Malfunction
1. Vehicle in Service Mode.
2. Verify the left and right turn signal indicators turn ON and OFF while commanding the Instrument Cluster Gauge Sweep Test ON and OFF with a scan tool.
• If the left or right turn signal indictors are always OFF or remain ON
Replace the P16 instrument cluster.
• If the left and right turn signal indictors turn ON and OFF
3. Replace the K9 body control module.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Front Turn Signal Lamp Replacement Service and Repair
* Tail Lamp Replacement Tail Lamp Replacement
* Turn Signal Multifunction Switch Replacement Turn Signal Multifunction Switch Replacement
* Control Module References Programming and Relearning for BCM or Instrument Cluster replacement, programming, and setup