I have a 1976 F250 4x4 and I can not get the dash lights to work. I have put in a new circuit board and all new bulbs and sockets, the signal indicator lights work and when I had the dash out for the 10TH time I noticed that the seat belt indicator light works and dims with the head light control. There is a small rectangular resistor or something that the circuit board plugs into similar to a 9 volt radio battery could that be bad. Any help would be greatly appreciated

 

Sounds like you might have a mis-matched harness and circuit board, either that, or some mis-routed wiring. The seatbelt warning light should never dim with the gauge lights.

 

Two different printed circuit boards:

With Oil/Amp GAUGES (1976/79 F100/350; 1976/91 Econoline; 1978/79 Bronco) or with Oil/Amp WARNING LAMPS (1976/78 F100/350, Bronco & Econoline).

 

That 9 volt looking thing is the instrument cluster voltage regulator. https://www.ford-trucks.com/forums/1...regulator.html

Might be time for a new headlight switch 1st off.

 

I was mistaken it is not the seat belt light it is the lights and wiper light

 

I was mistaken it is not the seat belt light it is the lights on and wipre light

 

Then the headlight switch rheostat sounds to be working. Does the heater control panel also brighten and dim?

I'd bet wiring issue for the clutter itself. X2 on you can not just swap a 4 gauge cluster in for a 2 gauge 2 warning light cluster.

 

FWIW, first thing I check when I have a lighting gremlin is the high-beam switch...bad switch, rusty floor, bad ground...those things can cause all sorts of lighting problems well beyond the hi/low circuit.