1989 chev 1500 no dash lights, but taillights
 

I am a new owner to a 1989 Chev 1500. It has no dash lights at all. when the lights are off, the fan indicator for the heat/air is on. When the head lights are turned on the light goes off and there are no dash lights either. I do have brake lights and turn signal lights. I was told it was probably my dash dimmer switch. Any suggestions?

i agree with the dimmer switch, try rolling the dimmer switch back and fort and see if if they flash on at all a lot of times the pots get dirty and will work momentary while adjusting them. but even if they don't flash on it does not necessarily rule it outs

Loosing ground , When you turn on head lights , it is taking a weak ground away from the dash light. Check your ground wires. Maybe run a new ground to dash lights.