Same problem with my 86...checked fuses, bulbs, replaced my dimmer switch, still nothing. I'm told theres a ground wire, near the ebrake(?) or brake pedal...I'm not sure though, havent been able to find out anything more on it...Check the ground first, unless you have tiny hands and an extra joint in your forearm, the dimmer switch is a royal pita to replace
I think its by the brake, If I remeber corretly.