1966 f100. 240. Truck was apart when i bought it and had been in the field unused for 15 years.

I have my truck back together after getting it running and paint is done. I am now getting ready to tackle the wiring. I have everything bolted on, the truck starts. Grounds from engine to cab, bed to frame, frame to cab.

I can get the headlights to only work by me adding a ground wire from the Black wire on the headlight three prong female plug and grounding it to the radiator support. Should I leave the ground wire that I have from the headlight harness going to the radiator supprt?

The front marker lights work in the halfway pulled out position on the switch. I think this may be correct?

I have no signal lights at the front marker lights. I do have signal lights in the rear but they are reversed. In other words, if i turn the selector to go right, the left rear goes on. And vice versa. I did not take the colum apart, but something must be switched at the connection of the turn signal switch to the harness?

I will not attempt the flasher switch until i get this other stuff figured out.

I do not have brake lights. I did a disc brake conversion and used the entire set up from a 1978 truck. I took the two wires from the brake light switch of the 78 and put them into the two wires that went to the sending unit.
that was on my single cylinder master in the 66.

Thanks. wiring is so hard.

 

I went under the dash with my test light to see if i cold find the rear signal lights switched at the plug and while i was testing, i lost the rear signal lights blinking, now they just stay on and not blink.

 

Wiring can be frustrating - corroded connectors, brittle wires, faded colors, Previous Owner 'improvements', etc. ; I just went through a similar situation last fall. You'll need a multi-meter and patience.

Here's my opinion:

Yep; at least that's what I would do.

Correct.


Brakes and turn signals use a lot of the same wiring, and a rather complicated turn signal switch under the steering wheel can cause all kinds of weird things. Under the dash, where the wires come out of the column, there is a two-wire connector that goes to the rear turn signals and stop lights. One wire is green and the other is yellow/black. It's a good place to start, you may have just knocked it loose.

There should be 12 volts on one of those pins at all times. When you hit the brake pedal, it closes the switch and passes the voltage on to the brake lights. So I would hook up the meter, hit the brakes, and see if the switch closes. If it does, then the problem is in the wiring.

This should help:
Wiring Diagram

 

Thank you very much for the tips. will get on it now.

 

Did some work and found the flasher must have died while i was testing. Replaced that and also found that the rear signal lights wiring were reversed by a splice by prior owner. Getting there. Thanks

 

Sounds good! My wires were so butchered up and so brittle that I replaced the whole harness.

 

Thanks for all the help. much appreciated.

 

The switch you hooked your brake lights to is probably the pressure differential switch that only activates when one brake line loses pressure. Search for a 78 F150 brake light switch and you'll see the one I installed on my '62 when I replaced my single pot MC with a dual pot. A thread I read here said the brake pedal has a rubber bumper at the top. Remove that and put this switch there. Worked out great for me. No mods needed other than running the original wires under the dash or finding them under the dash and removing the bumper.

 

I had a bad brake light switch. Thanks for the help.