Hello everyone yes I am new to this form. This is my first post with everyone. I have tried to search and have come up with a very close threads about what I'm about to ask. The issues I am running into are the ones that have photos that would best help me with my issue I cannot view.
So here are my questions I have a 76 F250 with a 79 F250 body on it. The wiring to the tail lights has been butchered throughout the years so I am currently re-wiring it as well as adding a fuel tank under the bed.
I attached a photo of the last few wires and I cannot figure out what they are too Or where they go. In the picture I included the color of the wire and the connector that would be on the end of the wire to maybe better help figure out what these wires are too and where they go. The colors are green with red stripe, brown with a purple stripe? A blue with no stripe, a purple with white stripe and a purple with no stripe. Thank you guys so much for your time.

 

The pics make all the difference.

The circuit most commonly associated with that is for the voltage regulator under the hood. I seem to remember that by '78 there may have been one or two more that used those colors so I'll check some diagrams and get back to you.

Doesn't ring a bell yet.

The connector looks like that might be for an interior map light, or perhaps the carburetor anti-dieseling, or high-idle solenoid.

Are the two purple wires you mention both on that same connector?
The Purple w/white and that "oval-ish" 2-pin connector look to be for the old brake warning lamp circuit.
Check down on the driver's side frame rail for your proportioning valve and see if it's got a plastic switch sticking out the side that matches that connector.

So that's just from memory. I'll check the wiring diagrams for both years and see what's up. Obviously those are not necessarily for the rear light harness you're working on, but probably came out of other areas during the swap-over.
The square-6 connector many of them are attached to looks almost like one of the earlier steering column connectors. Or maybe one near the driver's corner of the engine compartment? Not sure.
Someone will know that one I'm sure.

Good luck. Let you know if I find anything else.

Paul

 

Thanks for the replays everyone. I'll look when I'm off work in re guards to the break proportioning valve. I do believe that that is most likely where it goes now that you mention it. The other three. Came out of the wiring harness about midway under the bed.

 

For the 76 truck stuff:

There's a Green that is for a camper dome lamp. That would be under the bed of most trucks of that year even if they were not camper specials I would imagine. Maybe not, but it's a possibility.

There's a Brown for the rear running lights with camper and a control relay.
Don't think I've seen one of those under a bed, but might have missed it. Or the factory doesn't put them in all trucks if they don't have the running/marker lamps (like the optional type on the roof)
If the '76 has a lamp relay somewhere (never seen one so don't know where it would be) then any Brown wires could be for that.

There's also a Yellow w/black that's for trailer lights.
Or is that Yellow wire have a brown stripe?

So far anyway, it seems consistent with some unused trailer and camper light circuits.
Kind of an unusual connector for under the truck in my experience, but that doesn't mean it couldn't happen.

Paul

 

Ok this may start to make more since. If I am right then I think they took the wiring from the 79 and ran it in the fram too. The 79 is a ranger xlt camper special. Thank you for your help! Would you know what wires are for the fuel tanks be chance?

 

Usually Orange. But that may only be up in the cab, or for the main tank. Interestingly enough there is another Green wire for the mid-ship/side tank.
Maybe in the dual tank trucks, the rear tank was still Orange and the side tank sending unit was Green.

Paul