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.
Circuit Description
The ambient light sensor circuit provides an input to the BCM for DRL and automatic headlight functions. This input allows the BCM to activate or deactivate DRL and automatic headlamps with different ambient light levels. The BCM supplies a 5 volt reference circuit and a signal circuit to the ambient light sensor. The BCM will detect high voltage on the ambient light sensor signal circuit when ambient light is high, and low voltage when ambient light is low. The BCM monitors the ambient light sensor voltage at the signal circuit and determines if the voltage is within range. If the voltage is not within range, a malfunction is present and a DTC will set.
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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.