Headlamps Malfunction (With T4F)
Headlamps Malfunction (With T4F)
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 headlamp switch in the ON position, the headlamp switch headlamp ON signal circuit is grounded through the headlamp and panel dimmer switch. In response to this input, the body control module (BCM) provides ground to either the high intensity discharge (HID) headlamp control circuit or the headlamp high beam relay control circuit. The position of the headlamp dimmer switch determines which relay coil is supplied with ground. The underhood fuse block supplies battery voltage to the relay coil and switch circuits. The HID headlamps operate when the BCM grounds the HID headlamp relay control circuit to the HID headlamp relay coil. This energizes the HID headlamp relay coil causing the switch contacts to close. With the switch contacts closed, battery voltage is applied to the left and right HID fuses through to the left and right HID headlamps. When the headlamp high beam relay coil is energized, current flows through the left and right HIGH BEAM fuses to the high beam headlamps. With the headlamp dimmer switch in the high beam position the BCM sends a serial data message to the instrument cluster requesting to illuminate the high beam indicator.
The high beam and flash to pass functions are contained within the turn signal/multifunction switch. The BCM provides the turn signal/multifunction switch with two signal circuits, the high beam signal circuit and the flash to pass signal circuit. When the low beam headlamps are ON and the turn signal/multifunction switch is placed in the high beam position, ground is applied to the BCM through the high beam signal circuit. The BCM responds to the high beam request by applying ground to the high beam relay control circuit which energizes the high beam relay. With the high beam relay energized, the switch contacts close allowing battery voltage to flow through the high beam fuses to the high beam control circuits illuminating the high beam headlamps.
When the turn signal/multifunction switch is momentarily placed in the flash to pass position, ground is applied to the BCM through the flash to pass signal circuit. The BCM responds by applying ground to the high beam relay control circuit which energizes the high beam relay illuminating the high beams for a brief moment or until the flash to pass switch is released.
Reference Information
Schematic Reference
Headlights/Daytime Running Lights (DRL) Schematics Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
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 Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify the scan tool Headlamps On Switch parameter changes between Active and Inactive while commanding the headlamp ON and OFF with the headlamp switch.
• If the parameter does not change
Refer to Headlamp Switch Malfunction.
• If the parameter changes
3. Verify the scan tool Automatic Headlamps Disable Switch parameter changes between Active and Inactive while commanding the automatic lamp control ON and OFF with the headlamp switch.
• If the parameter does not change
Refer to Headlamp Switch Malfunction.
• If the parameter changes
4. Verify the scan tool Headlamps Flash Switch parameter changes between Active and Inactive while commanding the flash to pass ON and OFF with the turn signal/multifunction switch.
• If the parameter does not change
Refer to Turn Signal/Multifunction Switch Malfunction.
• If the parameter changes
5. Verify the scan tool High Beam Select Switch parameter changes between Active and Inactive while commanding the high beams ON and OFF with the turn signal/multifunction switch.
• If the parameter does not change
Refer to Turn Signal/Multifunction Switch Malfunction.
• If the parameter changes
6. Verify the low beam headlamps turn ON and OFF when commanding the Headlamp Low Beam Command ON and OFF with a scan tool.
• If the low beams do not turn ON and OFF
Refer to Headlamps Malfunction - Low Beam.
• If the low beams turn ON and OFF
7. Verify the high beams turn ON and OFF when commanding the High Beams ON and OFF with a scan tool.
• If the high beams do not turn ON and OFF
Refer to Headlamps Malfunction - High Beam.
• If the high beams turn ON and OFF
8. Verify the high beam indicator on the instrument cluster turns ON and OFF while commanding the All Indicators Test ON and OFF with a scan tool.
• If the high beam indicator does not turn ON and OFF
Refer to High Beam Indicator Malfunction.
• If the high beam indicator turns ON and OFF
9. All OK.
Circuit/System Testing
Warning
The high intensity discharge system produces high voltage and current. To reduce the risk of severe shocks and burns:
* Never open the high intensity discharge system ballast or the arc tube assembly starter.
* Never probe between the high intensity discharge system ballast output connector and the arc tube assembly.
Headlamp Switch Malfunction
1. Ignition OFF, scan tool disconnected, all doors closed, all accessories OFF, disconnect the harness connector at the S30 headlamp switch. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 15 ohms between the ground circuit terminal 6 and ground.
• If 15 ohms or greater
1. Ignition 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 15 ohms
3. Ignition ON.
4. Verify the scan tool Automatic Headlamps Disable Switch parameter is Inactive.
• If not Inactive
1. Ignition OFF, disconnect the X1 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 Automatic Headlamps Disable Switch parameter is Active.
• If not Active
1. Ignition OFF, disconnect the X1 harness connector at the K9 body control module, ignition ON.
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 Park Lamps Switch parameter is Inactive.
• If not Inactive
1. Ignition OFF, disconnect the X1 harness connector at the K9 body control module.
2. Test for infinite resistance between the signal circuit terminal 3 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 3 and the ground circuit terminal 6.
9. Verify the scan tool Park Lamps Switch parameter is Active.
• If not Active
1. Ignition OFF, disconnect the X1 harness connector at the K9 body control module, ignition ON.
2. Test for less than 1 V between the signal circuit terminal 3 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. Verify the scan tool Headlamps On Switch parameter is Inactive.
• If not Inactive
1. Ignition OFF, disconnect the X1 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
11. Install a 3 A fused jumper wire between the signal circuit terminal 4 and the ground circuit terminal 6.
12. Verify the scan tool Headlamps On Switch parameter is Active.
• If not Active
1. Ignition OFF, disconnect the X1 harness connector at the K9 body control module, ignition ON.
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
13. Test or replace the S30 headlamp switch.
Turn Signal/Multifunction Switch Malfunction
1. Ignition 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 15 ohms between the ground circuit terminal 3 and ground.
• If 15 ohms or greater
1. Ignition 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 15 ohms
3. Ignition ON.
4. Verify the scan tool High Beam Select Switch parameter is Inactive.
• If not Inactive
1. Ignition OFF, disconnect the X3 harness connector at the K9 body control module.
2. Test for infinite resistance between the signal circuit terminal 2 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 2 and the ground circuit terminal 3.
6. Verify the scan tool High Beam Select Switch parameter is Active.
• If not Active
1. Ignition OFF, disconnect the X3 harness connector at the K9 body control module, ignition ON.
2. Test for less than 1 V between the signal circuit terminal 2 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 Headlamps Flash Switch parameter is Inactive.
• If not Inactive
1. Ignition 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 3.
9. Verify the scan tool Headlamps Flash Switch parameter is Active.
• If not Active
1. Ignition OFF, disconnect the X3 harness connector at the K9 body control module, ignition ON.
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.
Headlamps Malfunction - Low Beam
1. Ignition OFF, disconnect the X1 harness connector at the K9 body control module, ignition ON.
2. Verify a test lamp illuminates between the B+ circuit terminal 4 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Test for less than 2 ohms in the B+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Test for infinite resistance between the B+ circuit 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 the test lamp illuminates
3. Verify a test lamp illuminates between the B+ circuit terminal 3 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Test for less than 2 ohms in the B+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Test for infinite resistance between the B+ circuit 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 the test lamp illuminates
4. Ignition OFF, connect the X1 harness connector at the K9 body control module.
5. Remove the KR49 headlamp low beam relay.
6. Connect a test lamp between the control circuit terminal 85 and B+, ignition ON.
7. Verify the test lamp turns ON and OFF when commanding the Headlamp Low Beam Command ON and OFF with a scan tool.
• If the test lamp is always OFF
1. Ignition OFF, disconnect the X5 harness connector at the K9 body control module, ignition ON.
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
3. Ignition OFF.
4. 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. Ignition OFF, disconnect the X5 harness connector at the K9 body control module.
2. Test for infinite resistance between the control circuit terminal 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 the test lamp turns ON and OFF
8. Ignition OFF, exterior lamps OFF, connect the KR49 headlamp low beam relay.
9. Ignition OFF, exterior lamps OFF, disconnect the harness connector at the appropriate T7 headlamp ballast.
10. Test for less than 5 ohms between the ground circuit terminal A and ground.
• If 5 ohms or greater
1. Ignition 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
11. Connect a test lamp between the control circuit terminal B and ground, ignition ON.
12. Verify the test lamp turns ON and OFF when commanding the appropriate Headlamp Low Beam Command ON and OFF with a scan tool.
• If the test lamp is always OFF
1. Ignition OFF, disconnect the X1 harness connector at the X50A fuse block - underhood.
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 KR49 headlamp low beam relay.
• If the test lamp is always ON
1. Ignition OFF, disconnect the X1 harness connector at the X50A fuse block - underhood, ignition ON.
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 KR49 headlamp low beam relay.
• If the test lamp turns ON and OFF
13. Test or replace the appropriate T7 headlamp ballast.
Headlamps Malfunction - High Beam
1. Ignition OFF, disconnect the X2 harness connector at the X50A fuse block - underhood.
2. Connect a test lamp between the control circuit terminal 31 and B+, ignition ON.
3. Verify the test lamp turns ON and OFF when commanding the High Beams ON and OFF with a scan tool.
• If the test lamp is always OFF
1. Ignition OFF, disconnect the X5 harness connector at the K9 body control module, ignition ON.
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
3. Ignition OFF.
4. 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. Ignition OFF, disconnect the X5 harness connector at the K9 body control module.
2. Test for infinite resistance between the control circuit terminal 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 the test lamp turns ON and OFF
4. Ignition OFF, exterior lamps OFF, connect the X2 harness connector at the X50A fuse block - underhood.
5. Disconnect the harness connector at the appropriate M28 high beam solenoid actuator.
6. Test for less than 5 ohms between the ground circuit terminal A and ground.
• If 5 ohms or greater
1. Ignition 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
7. Connect a test lamp between the control circuit terminal C and ground, ignition ON.
8. Verify the test lamp turns ON and OFF when commanding the High Beams ON and OFF with a scan tool.
• If the test lamp is always OFF
1. Ignition OFF, disconnect the X1 harness connector at the X50A fuse block - underhood.
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 X50A fuse block - underhood.
• If the test lamp is always ON
1. Ignition OFF, disconnect the X1 harness connector at the X50A fuse block - underhood, ignition ON.
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 X50A fuse block - underhood.
• If the test lamp turns ON and OFF
9. Test or replace the appropriate M28 high beam solenoid actuator.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Headlamp Replacement Headlamp Replacement
* Headlamp Bulb Replacement (RS) Headlamp Bulb Replacement (RS)Headlamp Bulb Replacement (SS HID) Headlamp Bulb Replacement (SS HID)
* Headlamp Ballast Replacement (HID) Headlamp Ballast Replacement (HID)
* Accessory Wiring Junction Block Replacement Removal and Replacement
* Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)
* Turn Signal Multifunction Switch Replacement Turn Signal Multifunction Switch Replacement
* Headlamp, Instrument Panel Lamp Dimmer, and Fog Lamp Switch Replacement Service and Repair
* Control Module References Control Module References for BCM or instrument cluster replacement, programming, and setup