I have a 2006 duramax 2500. While driving, one of my lowbeam lights went out. I replaced the bulb but it still didn't work. I checked the fuse and the fuse is fine as well. I was told that the dimmer switch on the steering column might be the problem. I haven't been able to find a wiring diagram to check for a short in the wiring. I thought I might check the wiring before I buy a new switch. Any ideas?
I don’t have a wiring diagram but it would seem that your dimmer switch would be common to both headlites. Best to start at the problem, i.e. the nonworking bulb, and trace back from there for voltage.