Intermittent issue with the headlights not working properly

LOOSEPRIMER

MEMBER
2001 CHEVROLET SILVERADO
6.6L
V8
4WD
AUTOMATIC
250,000 MILES

When I turn my truck on while headlight dial is on automatic sometimes only one headlight will turn on. It seems to alternate which one some days. If I manually override and turn them off by pressing a button repeatedly to turn off I can then usually turn both headlight on by rotating the dial switch to the on position. Does any one know the cause of this or a solution?

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
47,513 POSTS

It sounds like there is a problem with the BCM. to be sure here is a guide to check the power output of the switch and the wiring diagrams so you can see how the system works:

https://www.2carpros.com/articles/how-to-check-wiring

a CAN scan will help see if the BCM is bad which is the future of automotive repair you can get a CAN scanner from Amazon for about $50.00. here is a video to show you how:

https://youtu.be/InIlnsjOVFA

Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem. I have included BCM replacement instruction as well.

Images (Click to make bigger)