1991 GMC Van Repair Question
GMC Van Dimmer switch Problem
Have you checked the fuses? Also do you have a multi meter to do some testing?
23,193 answers provided
That's what you pay mechanics to diagnose. The most likely cause is a defective head light switch, especially if the tail lights also don't work. The next suspect would be the dimmer switch. Check both connectors for blackened terminals or signs of melted plastic.
17,324 answers provided