I recently purchased this 1968 F-100 short bed, in excellent shape. The only thing I will gripe about is the mess of a wiring job that is in this truck. Not just under the dash but all over, it is a complete nightmare. I will eventually rewire the entire thing, but until I have the time to do it, I am repairing only the things that are crucial for now. Back to my problem. The other night sitting in a parking lot with engine running, it started to get pretty hot, the guage in the dash never runs over the "C" mark, but it got to the middle of the guage while it was sitting there, a few moments later my headlights went out. So I shut the motor off and turn the lights on and off again a couple of times and they came back on about the fourth try. So I drove home. When I got home I shut everything off and went inside for about 30 minutes then came back out to see if they were going to give me anymore trouble. Well sure enough the headlights wouldn't come on. I tried and tried for the next several days, but they would never come back on. So I ran and picked up a new headlight switch and put it on last night, but the headlights still are not working. I have checked fuses, bulbs, loose wires, but have come up with nothing. All of my other lights, turn signals hazards are still working. I did notice that my front parking lights go out when I pull the switch all the way out for my headlights. Does anyone have any suggestions as to what to try next? Thanks in advance.

 

Sure seems like the headlight switch, but possibly a bad wire in the connector?? Also, the grounds are very important with the lighting system.

Pete's Ponies
Mustang RUSToration & Performance

 

Maybe try wiggling your dimmer switch, the headlight power goes through it.

 

Could even bypass the dimmer switch with a jumper wire to see if you get lights. Disconnect the dimmer and jump from lower wire, think it is red with yellow stripe, to anyone of the others you will either get high, low or no lights when you turn on the headlights. If you get lights it is a bad dimmer switch. If you dont get lights try any combination of these 3 wires jumped together 2 at a time. You won't hurt anything dont worry, you are just replacing the switch with the jumper wire.
If you still don't have lights you can use a jumper to put 12 volts direct to the dimmer light connector, pick a wire, one of them should give you headlights if the lights, the wires to them and their grounds are good.
If you get lights it is the power feed from the fuse. If you don't get lights check the grounds and the headlight connectors for corrosion, come to think of it probably should check these first But I cant see both headlights losing their grounds at the same time, or both hi and lo power wires to the headlights. Unless the wire bundle in the engine compartment burnt up.
Oh yeah make sure the dimmer switch connector isn't full of corrosion, if it is you will be chasing problems that don't exist.
Since you tried a new headlight switch with no luck, I would lean towards the dimmer switch or a bad power wire to the headlight switch or from the headlight switch to the dimmer switch.
Gotta go starting to ramble
Keep in touch.

Sparky

 

I had the same problem on an old 73 I had I replaced the dimmer switch. Nonthing like going down the road at night and the lights going on and off.

 

68 Ford,
This is a classic Ford Truck problem. If you can isolate the headlight switch as "good" then its got to be the Hi/Lo Beam switch. It's not bad, but it is possible to kick it loose while sitting around in your truck "not driving" if you know what I mean. Ford trucks are great for cruising, but they're even better for other things.
Good Luck, Have Fun,
Kingfisher

 

THANKS A LOT FOR ALL OF THE REPLIES. YA'LL WERE RIGHT ABOUT THE DIMMER SWITCH. I TAPPED ON IT A FEW TIMES AND MY HEADLIGHTS STARTED WORKING AGAIN. COMPLETELY FORGOT ABOUT THE DIMMER SWITCH BEING A PART OF THAT CIRCUIT. PROBLEM SOLVED, THANKS AGAIN FOR THE INFO.

 

I can tell you’re really excited about it (all caps.) Thanks for the follow-up, wish more posters would do that. You probably want to go ahead and replace the dimmer switch, it’s on its way out.

Barry

 

ALREADY DID THAT. DID NOT WANT TO HAVE TO WORRY ABOUT IT,BEING THAT TOUCHY. THANKS AGAIN.