if your switch is turning on and off that means the Circuit breaker inside the switch has gone bad or is overloading.
I had an issue with the switch turning on and off because i used 85 Watt Halogen headlights and the system was overloading the circuit breaker then flicking on and off. i had to use 35watt reproduction ford headlights which stopped the problem from occurring at loss of brighter lights at night.
the safest way to put in larger headlights is to use a Relay system, so the headlights switch drives a low power relay that allows the headlights on a separate circuit to get a full 12Volt feed off the battery, the switch will not pull the amps from that system and overload.
as far as the dash not working, there is a small fuse for the dash lights i think its a 7A pull it out of the fuse box.
use a volt meter turn on the headlights switch and place positive on the fuse ear, and place Negative on the car body, any bare metal and see if you get 12 volts. if you get 12 volts without the fuse, use an ohm meter on the fuse you can get defective fuses its all made in china junk now. either way try replacing the fuse and make sure the fuse ears in the fuse box are clean with no Green build up on the connections.
Now check is only the main instrument cluster lights not working or is it the entire dash.
if you have center gauges see if they are lit up, is the gear shifter light if you have an automatic working.
if just the instrument cluster lights are out and all the other lights are working, check the High and low beam light is the horse lighting up?
are the turn signal indicators working?
does the Brake light come on when your starting the car?
all this will help pin point whats not working.
lets say all the other lights and gauges work but the main instrument lights are still out.
reach behind the dash you will be able to grab hold of one of the little twist on light holders, with the dash working, mess with it untwist and twist it, take it out and put a 9volt battery on it make sure the light actaully works. if it still won't light up, then pull the dash cluster.
unplug the main harness, and get out your volt meter and test the one connector that powers the lights, an osbourn manual will really help figuring out what connector you want.
if the connector is getting power then you will need to test the circuit board. use some alligator clips and a 9 or 12 volt battery and manually power the dash and verify you can get the lights to work.
I had to go through this because i kept having bad contacts with the little twist in light holders. i used dielectric grease on all connections to try and reduce oxidation problems. i also had bad contact with a fuse once that knocked out my A/C blower fan, just a little oxidation and things don't work.
I also had issues with the reproduction circuit boards making contact with the main harness plug, clean everything up with a pencil eraser and i used dielectric grease on the connections and i made sure the circuit board connections at the harness connector lined up 100% i kept having to go back and forth resetting the connection because i would knock out my turn signals, or then 1 or 2 bulbs on the speedometer or tach would go out and i would have to reset it to get them to light up. very annoying dealing with old oxidized connections.
1) first make sure power is getting to the fuse box.
2) then make sure its getting through the fuse itself.
3) diagnose exactly what is out on the dash to pinpoint the problem. if all the lights are out then you know you need to look at the fuse box, and the main harness.
if just the main dash lights are out but the center works and the warning and gauges work then you know its an issue either with the plug in connector or the individual lights themselves.
I'll check it out
