Headlight Wiring Diagram Chevrolet Silverado
Here’s the headlight wiring diagram for a Chevrolet Silverado with DRL
If you want to troubleshoot a headlight problem in your Chevrolet Siverado, you’ll need this headlight wiring diagram. Unlike many other headlight systems, the normal headlights and DRL lights are two separate systems, but they’re both controlled by the body control module (BCM).
When you turn on the headlights, the headlight switch passes battery voltage through the headlight switch to the BCM. The BCM sees the voltage and provides power to the control coil on the headlight relay. That closes the contacts and provides power to both the left and right headlights.
DRL wiring diagram
The DRL system is different. The BCM looks at the input from the ambient light sensor. If it sees daylight and the parking brake isn’t set, the BCM provides ground to the control coil in the DRL relay. Once the control coil has ground, the contacts close and the relay provides power to the DRL lights.
If the DRL lights stay on, that indicates a problem with stuck contacts in the DRL relay, a short to ground in the control coil wiring, or a problem in the ambient light sensor that tricks the BCM into thinking it’s daylight all the time.