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Headlamps Malfunction - High Beam




Headlamps Malfunction - High Beam

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

The headlamp high beams are controlled through the flash to pass switch and the headlamp dimmer switch, both located in the turn signal/multifunction switch. The flash to pass switch is a momentary type switch, designed to illuminate the high beams as long as the switch is held. With the switch closed, the flash to pass switch signal circuit is grounded, prompting the BCM to turn on the high beam lamps. The headlamp dimmer switch allows the operator to select between full time high or low beam operation. Unlike the flash to pass switch, it is not a momentary switch. When the headlamp dimmer switch is in the high beam position, the headlamp dimmer switch high beam signal circuit is grounded. This prompts the BCM to turn on the high beam lamps.

Reference Information
Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference

Component Connector End Views Connector End Views By Name
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, headlamps ON, observe the scan tool High Beam Select Switch parameter while selecting between the low beam position and the high beam position on the turn signal/multi-function switch. The value should change between Inactive and Active when changing between the selected states.

• If a value does not change between the commanded states, refer to Turn Signal/Multifunction Switch Malfunction.

2. Observe the scan tool Headlamps Flash Switch parameter while pulling and releasing the turn signal/multifunction switch. The value should change between Active and Inactive each time the switch is pulled and released.

• If a value does not change between the commanded states, refer to Turn Signal/Multifunction Switch Malfunction.

3. Command the High Beams ON and OFF with a scan tool. The high beam headlamps should turn ON and OFF when changing between the commanded states.

• If the high beam headlamps are always ON or always OFF, refer to Headlamp High Beam Malfunction.

Circuit/System Testing

Turn Signal/Multifunction Switch Malfunction
1. Ignition OFF, disconnect the X2 harness connector at the S78 turn signal/multifunction switch.
2. Ignition OFF, test for less than 30 ohm between the ground circuit terminal 3 and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the scan tool Headlamps Flash Switch parameter is Inactive.

• If not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the K9 BCM.

4. Install a 3 A fused jumper wire between the signal circuit terminal 4 and ground. Verify the scan tool Headlamps Flash Switch parameter is Active.

• 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 K9 BCM.

5. Verify the scan tool High Beam Select Switch parameter is Inactive.

• If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the K9 BCM.

6. Install a 3 A fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool High Beam Select Switch parameter is Active.

• If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the K9 BCM.

7. If all circuits test normal, test or replace the S78 Turn Signal/Multi-Function Switch.

Headlamp High Beam Malfunction
1. Ignition OFF, disconnect the X2 harness connector at the X50A underhood fuse block.
2. Connect a test lamp between the control circuit terminal 29 and B+.
3. Command the High Beams 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 ground. If the circuit tests normal, replace the K9 BCM.

• If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.

4. Ignition OFF, connect the X2 harness connector at the X50A underhood fuse block. Disconnect the inline harness connector listed below:

* E5E headlamp-left high beam inline harness connector X115 (Without TT6/TT7/TT8)
* E5E headlamp-left high beam inline harness connector X111 (With TT6/TT7/TT8)
* E5F headlamp-right high beam inline harness connector X116 (Without TT6/TT7/TT8)
* E5F headlamp-right high beam inline harness connector X112 (With TT6/TT7/TT8)

5. Connect a test lamp between the control circuit terminal C and ground.
6. Ignition ON, command the High Beams 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 X50A underhood fuse block.

• If the test lamp is always OFF and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, replace the X50A underhood fuse block.

• If the test lamp is always OFF and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the E4 headlamp

7. If all circuits test normal, replace the E4 headlamp.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Turn Signal Multifunction Switch Replacement Turn Signal Multifunction Switch Replacement
* Fuse Block Replacement Fuse Block Replacement
* Headlamp Replacement Headlamp Replacement
* Control Module References Control Module References for BCM replacement, programming and setup

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