Trailer wiring

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Turbo4whl

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Some info that may help with all wiring upfits. I had a trailer with electric brakes for a safety inspection. Trailer brakes would work with the brakeaway cable pulled, but not through the truck/trailer plug. I found the builder used sealacrimp conectors.
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Notice the connector upper left with blue wire. The seal over part of the loop prevented the nut from tightening the nut to the metal loop. You can also see how a new connector, upper right also has sealing plastic on the loop, just not as much.

This trailer, two axle 12x4" brakes has a GVRW of 19,300 pounds. It can carry 3 large cable reels. Here is the factory wired connection box. (I use the word factory loosely)

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bucket

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Hey I've got a somewhat related question that you may know the answer to. We got 4 new International medium duty trucks and we ordered the "in-dash" trailer brake controllers. Well, it turns out, that option simply means that the dealer installs an aftermarket brake controller to the underside of the dash. It's a joke really. But anyway, all 4 trucks will apply braking power to a trailer, but they do not show connection on the controller so it makes it a real guessing game to adjust brake bias. I haven't had much time to investigate... do you have an idea of what they might have done wrong? It's only 4 wires, I don't know what they could have possibly done.
 

bucket

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bucket

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K5 thru K30
Engine Size
350-454
Also, something else that puzzles me is the wiring at the back of the truck. We ordered the optional rear body harness as well as a trailer plug harness. As delivered, the wires are not labeled for function, some of them are odd colors and many of them are just orange. The dealer we purchased the trucks through could not provide us with a schematic of any kind. I went through and figured them out, but each truck has a wire that is a constant 5 volts. It's part of the body harness which are all heavy gauge wires (trailer harness plugs are all smaller gauge wires). Pretty dumb, I think.

Long story short, I have no idea what use there would be for a constant 5v supply. Even the 12v Aux power wires are ignition switched.

I forgot I have a picture of the body harness:
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