Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Test
- CHECK FOR AN ACTIVE DTC
- Turn the High Beam Headlamps on.
- With the scan tool, read the Body Control Module (BCM) DTCs and record on the repair order.
Is the DTC active?
Yes
- Go To 2
No
- The condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals and correct pin tension. If no problems are found, test complete.
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
- CHECK THE (L33) LEFT HIGH BEAM DRIVER CIRCUIT FOR A SHORT TO VOLTAGE
- Turn the Headlamps off.
- Turn the ignition off.
- Disconnect the Left Front Lamp Assembly harness connector.
- Disconnect the BCM C4/D harness connector.
- Turn the ignition on.
- Measure the voltage between ground and the (L33) Left High Beam Driver circuit at the BCM C4/D harness connector.
Is there any voltage present?
Yes
- Repair the short to voltage in the (L33) Left High Beam Driver circuit.
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
No
- Go To 3
- CHECK THE (L33) LEFT HIGH BEAM DRIVER CIRCUIT FOR AN OPEN
- Turn the ignition off.
- Measure the resistance of the (L33) Left High Beam Driver circuit between the Left Front Lamp Assembly harness connector and the BCM C4/D harness connector.
Is the resistance below 3.0 Ohms?
Yes
- Go To 4
No
- Repair the open in the (L33) Left High Beam Driver circuit.
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
- CHECK THE (Z906) GROUND CIRCUIT FOR AN OPEN
- Check for continuity between ground and the (Z906) Ground circuit at the Left Front Lamp Assembly harness connector.
Is the resistance below 3.0 Ohms?
Yes
- Go To 5
No
- Repair the open in the (Z906) Ground circuit.
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
- Check for continuity between ground and the (Z906) Ground circuit at the Left Front Lamp Assembly harness connector.
- CHECK THE BCM FOR CORRECT OPERATION NOTE:
The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.
- Reconnect the BCM C4/D harness connector.
- Connect a 12-volt test light between the (L33) Left High Beam Driver circuit and (Z906) Ground circuit in the Left Front Lamp Assembly harness connector.
- Turn the ignition on.
- Turn the High Beam Headlamps on.
Does the test light illuminate brightly?
Yes
- Replace the Left High Beam Shutter Solenoid in accordance with the Service Information. Refer to UNIT, FRONT LAMP, REMOVAL .
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
No
- Replace the Body Control Module (BCM) in accordance with the Service Information. Refer to MODULE, BODY CONTROL (BCM), REMOVAL .
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.