My 86 F-150's headlights are out and i have tried to figure out whats wrong with them but i need some good advice. I tested the dimmer switch and one of the wires has voltage but the other two don't. Neither headlight works or my parking lights but the fuse for my parking lights is blown so i think theirs a short somewhere but i'm trying to fix my headlights first. i tried testing the headlight switch but am not sure which wires to test with the multimeter. Thanks in advance for any help.

 

Have you looked at the wiring at the headlight switch? There is a tan wire that sometimes melts at the switch and can short out with other wires..

 

Before you test with a multimeter use your eyes on the wires at the headlight switch. These trucks run all of the current for the lights through that switch and its associated wiring, and while that stuff was barely up to the task when new, it is no longer new. Melted wires at the headlight switch are getting all to common on here. The wires get so hot they melt their insulation off and either sort on a ground or connect to another wire and give you really screwy problems.

So slide under and see what you can find. Meanwhile I'll try to remember to post a wiring diagram tomorrow.

 

Only 1 wire should have voltage going to the dimmer. The question is, does any voltage occur at those other 2 wires when the dimmer switch is plugged in? 1 is out to low beam, the other to high beam.
You've got power getting to the dimmer, but is it getting thru it?

 

Yes, plug the switch back in, but not all the way so you can put the meter on the terminals and see if it has voltage. Going from memory, the red/black is the one coming from the headlight switch. Or, leave the plug unplugged, take a paperclip or piece of wire and jump from the wire that has voltage to one of the others. You should have high or low beams.

 

Ok thanks guys, ill try that. I have to say that out of all the sights i have been on this one has to be the best, you get lots of input and good answers.

 

It was the dimmer switch, thanks for all the help guys.

 

Glad you figured it out and, hopefully, got it fixed.

 

Is there a good headlight relay set up so all power does not run through the switch?
Won't lights be "brighter" this way?

 

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Yep. Several places carry them, like this one at one of our sponsors Jeffs Bronco Graveyard. The only current on the headlight switch then is the 1/10 of an amp or so that it takes to pull the relays in. Highly recommended.

 

Whiter Whites, Brighter Brights .: Articles

 

I bought one, it's also fused...seemed reasonable...took a week to get here from China, though ~Bill

 

Research those headlight relay kits. Some of them are so cheap, if you figure your time and the cost of the relays and the wiring, you cannot do it as cheap making one yourself. I looked at one from LMC and it has the correct plugs and everything so it just plugs in.

 

Amen! I built my own and could have bought LMC's for the same price. The only advantage to building your own is you can place the components where you want them. Probably not worth it.