What do all These Wires Do?

[ClassicIDI]

So I went to wire a new trailer plug on the back of my truck and found a bunch of wires that go no where but I would like to know what they do. So hopefully some one with a factory manual can tell me what they are for.
There are four plugs and two of which have three wires and one has two wires and the last one just has one wire. I have taken a voltmeter and found what some of them do but if some could confirm what I have found out and tell me what the rest of these wires do it would be much appreciated.

Here are the plugs together

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And the forth plug is more towards the center of the truck Here

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Now individually the first plug has a large yellow wire, red w/yellow stripe, and blue w/ black stripe and I have no idea what any of these do

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The next plug has a black wire (which appears to be the running or tail lights), a green w/orange stripe (which is left turn signal), and a orange w/blue stripe ( right turn signal)

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The next plug has two connections which are a bigger white wire (ground) and a Black w/pink stirpe (reverse lights)

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And the last plug is a single brown wire, which i don't know what it does either

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[Mr_Roboto]

That little plug in the center is probably for the license plate light.

I'm going to guess that your truck came from the factory with an RV plug which would have a trailer brake wire, battery wire etc. I had an 85 that had the factory RV plug. That would explain the extra connectors and the heavy wires.

Someone probably replaced the factory plug with an aftermarket one, then removed the plug when they sold the truck.

 

[82fordtruck]

I have the pigtails to connect to those. They're free for the taking if interested.

 

[ClassicIDI]

The rv package makes sense so those wires probably go to some place under the dash I think that the large yellow has power when the key is on . The one brown is not license plate because there is another plug with those two lights on it. Thanks for the offer on the pigtails but I have those I just need to figure out what to connect them too.

 

[Agnem]

Usually, on a Ford the brown wire is running lights.

 

[82fordtruck]

I think it's for the lights under the tailgate, factory on duallies. The big plugs are trailer wiring.

 

[ClassicIDI]

Usually the brown is running lights and I may try and trace it latter to see where it goes. When I bought the truck it had a rear bumper on it and it had lights for the plate which were pluged into yet another plug. I took the bumper off along with the license plate lights to put my lift gate on. I still think that the one center plug is for license plate lights though i don't know why ford would put two plugs for the same purpose.

 

[82fordtruck]

Some of the trucks had the three running lights underneath the tailgate, like on the duallies. I think it's for this.