I bought a 1991 GMC Jimmy and realized after buying it that the headlights and tail lights would not go on. Of course, this was an 'as is' truck so i am on my own with fixing it. So far i checked the headlight switch for power and there is juice going to the headlight switch. Not sure how those work though. The connections look and feel strong at the headlights. Could not find a fuse for them, so was wondering if anyone has knowledge of where the headlight fuses are and whether or not this sounds like a switch problem or grounding problem. Brake lights and reverse lights work fine. According the the lady that traded the truck in, the lights were working fine. Not overly sure if she is telling the truth though.

 

I figured out by process of elimination that the headlight switch wore out. It didn't feel right when you pressed the buttons so went to junk yard and bought one and it worked fine.

 

SWEET! Thanks for giving us your answer to your problem! Good detective work Dano