Tail light wiring harness question
 

I'm splicing the pigtail onto the wiring harness of my new-to-me bed for my 66 F100 shortbed. The PO cut the wires rather than disconnecting the plug. I have a yellow, green & 2 brown wires. The yellow & green are obvious but does it matter which way the 2 brown wires are connected? Thanks for the help!!

3 wires is correct, I don't recall which is which but it doesn't matter.

1 is tail light, license plate.

The other 2 are left & right turn signal/ brake. The brake & ts share so turn the ign. switch on move the ts to start it flashing and with a circuit tester you can correctly identify left or right at the rear.

Piece o cake.




John :-X06

Thanks for the response, John, but mine has 4 wires - 1 yellow, 1 green, 2 brown. If the brown ones are for the running lights, then it probably doesn't matter which goes to which but if not, then I'll have to figure that out. I don't really have a circuit tester, but I'll figure something out.
Thanks. If anybody knows specifically what each colored wire is for, that would be helpful.
Thanks again.

If you look at this thread and go to post#6, you will find a wiring diagram that should answer all of your questions. You need Adobe Acrobat Reader to view the file. I saved a copy of it on my hard drive and laminated a printout for reference.

Mark

https://www.ford-trucks.com/forums/1...horn-wire.html

Thanks, Mark!!! That's just what I needed.:-jammin

According to the 66 wiring diagram I have yellow black should be your rt side directional and the green should be the lft side directional the brown is for tail and license plate lights.;)

37 Your truck has backup lights, that fourth wire is for that.

Get a circuit tester like this one, it makes tracing wires much simpler.

https://www.ford-trucks.com/forums/p...ictureid=19134


John :-X06

John, I'm not aware of any '66 having backup lights. I thought backup lights were '67 and up.

Mark

You are correct 66-f100...wiring harnesses...for those who have the parts catalog...are a tedious thing to look up...

No backup lights on trucks from the factory until 1967 model year.


- cs65

You tell me what he has with 4 wires then.



John :-X06

I just did this last week when I put the new bed on my '59. I think he has 2 brown tail light wires is because he is past the part where the brown wire splits into two. One for each side and they're the same circuit, so really you're both right as the brown wire at some point splits to feed the right side tail light but in some ways it's the 'same wire'. My .02

Could it have had a tow package installed at some point? then the plug was cut off
leaving extra wire?

If he started to check his bed wiring some where after the molex connector with the 3 wires comming from the front of his truck. He may have more than 1 brown wire as a brown wire goes to each tail light and another would go to the license plate light. That would be a total of 3 brown wires depending on where he was looking.

The wiring for the rear lights that runs along the frame rail has 3 wires where it ends at the frame rail......green, yellow and brown. Green and yellow are right and left tail lights respectively. The brown is where the license plate light is fed off of. The light sockets/buckets ground themselves to the body/frame of the truck.
The brown is connected to each other within the harness...a simple continuity check will confirm that if its as originally made. The tail light harness that runs across the rear of the bed is the same way.



- cs65

Thanks guys for all the help & comments. To follow up, according to wiring diagram referenced above, the green is the left directional light, yellow is the right directional light and a brown wire also goes to each taillight plus the tag light. There is a connector right before the last cross member at the rear of the chassis. It's at that connector that the brown wire goes from a single wire to two brown wires plus the yellow & green. I didn't know that when I first posted the question. Since the 2 brown wires come from a single brown, it didn't matter which one I attached to each other. I have now attached each of the wires on the pigtail to their respective colors on the tail light harness and it all works great. Thanks again for all your help!!

ps: there is a trailer light harness spliced in there too but that didn't affect my original question.