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 ignition 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 (L89) LEFT FRONT FOG LAMP CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
- Turn the ignition off.
- Disconnect the Left Front Fog Lamp harness connector.
- Disconnect the BCM C1/A harness connector.
- Turn the ignition on.
- Measure the voltage between ground and the (L89) Left Front Fog Lamp Control circuit.
Is there any voltage present?
Yes
- Repair the short to voltage on the (L89) Left Front Fog Lamp Control circuit.
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
No
- Go To 3
- CHECK THE (L89) LEFT FRONT FOG LAMP CONTROL CIRCUIT FOR AN OPEN
- Turn the ignition off.
- Measure the resistance of the (L89) Left Front Fog Lamp Control circuit between the Left Front Fog Lamp harness connector and the BCM C1/A harness connector.
Is the resistance below 3.0 Ohms?
Yes
- Go To 4
No
- Repair the open in the (L89) Left Front Fog Lamp Control circuit.
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
- CHECK THE (Z901) GROUND CIRCUIT FOR AN OPEN IN THE HARNESS
- Measure the resistance between ground and the (Z901) Ground circuit at the Left Front Fog Lamp harness connector.
Is the resistance below 3.0 Ohms?
Yes
- Go To 5
No
- Repair the open in the (Z901) Ground circuit.
- Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
- Measure the resistance between ground and the (Z901) Ground circuit at the Left Front Fog Lamp harness connector.
- CHECK THE BCM FOR CORRECT OPERATION
- Reconnect the BCM C1/A harness connector.
- Turn the ignition on.
- Turn the Fog Lamps on.NOTE:
The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.
- Connect a 12-volt test light between the (L89) Left Front Fog Lamp Control circuit and the (Z901) Ground circuit at the Left Front Fog Lamp harness connector.
Does the test light illuminate brightly?
Yes
- Replace the Left Front Fog Lamp in accordance with the Service Information. Refer to LAMP, FOG, FRONT, 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.