I have a 1976 F100. I am having tailight problems that I think are related simply to the wiring connections where the tailights are connected in the rest of the electrical system. I think what I need to fix them is the wiring for the tailight, but I don't know where to find this. All I can seem to find is the tailight assembly which doesn't include the electrical part of the tailight. Does anyone have any suggestions on where I might find this or on how I might fix my problem?

 

Brown is the running lights & License plate light.

I think there are Blue & Red wire for T/S/Brake light

 

Welcome to FTE...

There is a good tech article about troubleshooting and repairing tailights (in the TECH ARTICLES link in the upper right hand corner of the page). I don't think the wiring harness is available new, you will have to repair the one you have or find a better one in a salvage yard.

Marty

 

I experienced the same problem with my 76 f-250. The taillights and turnsignals worked sporatically and often glowed dimly. I ended up removing the rear portion of the truck's wiring harness and using it as a guide to make a totally new one.

I found new bulb sockets at the local O'Reilly's parts house, marine grade tinned copper wire and heat shrink tubing at a local West Marine. I soldered all joints and covered them with heatshrink. I cut off and reused the OEM plug that connected the rear harness with the rest of the truck's wiring harness, the OEM grounding wires (cut and resoldered to the new bulb sockets) and the OEM connecters for the liscence plate lights. I after soldering it together, I wrapped it in electrical tape and covered it with the flexible plasitic wiring loom to update the look and protect the wires. I even added a totally separate sub-harness for the trailer wiring using the combination 7 pole rv connector and 4 pole flat trailier connector found on late model fords. In fact, I got it off of a 99 model f-150 I found in the local wrecking yard.

Everything works great now.
Even the lights on my boat trailer work great and shine brightly.
This did envolve a little work and about 40 bucks in parts, but it sure is worth it when I go to get the truck inspected or pull the boat at night.

 

The biggest problem with these old trucks is the ground thru the body/frame goes bad. Years of corrosion will do things like that.

 

Yuup, what Eric said. It can show up in some really interestng way's too.
I bought a whole Tail light assembly for my 77 from NAPA in '96', Wires and all.
I've repaired it all too, but buying the new stuff is soooooo much more to my liking.