In my 1979 ford f150 custom, when i turn on the high beam headlights after a few minuets the whole light system shuts down. Was wondering if anybody had this same issue and has found a fix for it. Please any advice will help. Thanks

 

The problem is probably a bad headlight switch but could also be a bad dimmer switch. I'd check the wiring at the dimmer switch and if that's ok pull the headlight switch out and see how the contacts look there, best bet though is the headlight switch.

 

Do the headlights stay off or do they come back on?
The headlight switch has a circuit breaker built into it. It's the type that resets automatically.
This is a common failure on old switches. The headlights go out and after a few seconds, they come back on.
If the circuit breaker is tripping, you also need to check the circuit for any shorts, bare wires, cracked insulation, pinched wires, etc. The headlight switch could be bad, but it might be the circuit breaker is doing it's job.

 

If the switch is bad, replace it and do this.

https://www.ford-trucks.com/articles/whiter-whites-brighter-brights/

One of the best upgrades I have done on my truck.

 

As Mike said, you need to determine if the headlights are shutting off because the breaker is tripping. Look downstream for any obvious pinched or frayed insulation. Don't go spending your $20 on a new switch just yet.

Any chance you had the front clip off or did a body swap recently? Over half of these threads start the exact same way, and the OP conveniently forgot to mention that half of the truck's sheet metal has been moved around.

 

Common problem: Corroded dimmer switch will cause the headlamps to turn off when selecting the high beams.

COTZ-13A024-A .. Dimmer Switch (Motorcraft SW-263) / Myriad 1960/96 FoMoCo vehicles.

 

I have had the front clip of the body off to rebuild the engine in the truck recently. My dad had this truck before i got it and he has had this problem for years. The lights do not come back on with out me shutting off the switch and turning it back on a few times.

 

That description sounds like a bad switch. Unless you know the trick, they can be a bit of a pain to remove. The switch's **** and shaft are released by a button on top of the switch. You depress the button and pull the **** and shaft out.

 

Ok i will replace that switch and see if it works. Thank you to all of you that have helped me.