Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Hi Shaggy, I'm Clay a certified master automobile technician with 30 years of automotive repair and diagnostic experience.
From your description you may have a couple of problems. Before condemning the BCM there are some other areas to look first. Lets start with the Daytime Running Lights (DRL). Check the headlight fuses by removing each fuse and inspecting (the circuit can back feed and show power on both sides of a blown fuse). Check the DRL resistor located behind the right headlamp (Gray wire and Black wire go to the resistor). Ohm test the resistor and replace if open. Also make sure the parking brake is not set. If you need the service procedure for the DRL resistor let me know.
For the low beams ground the Dark Blue wire at either low beam lamp. Check for both left and right low beam lamps to come on. If the lamps come on, remove the ground wire at the lamp and ground the Dark Blue wire at the headlamp switch. If grounding at the lamps turns the lamps on, and grounding at the switch does not check the Dark Blue wire for an open wire from the lamps to the headlamp switch. If the low beams come on by grounding the Dark Blue wire at the lamps and and at the switch, the switch is not providing a path to ground. If you need a circuit diagram let me know.
I hope this information is helpful. If you have any questions or run into any problems let me know.
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