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?