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Discussion Starter #1
I just bought a car hauler and when I plug the lights up, the trailer brakes lock up when I hit the brakes....when I umplug the lights, I have no trailer brakes, does this truck have a factory brake control? previous owner had one mounted in there, you can see the holes where it was, so putting an aftermarket controller on there will fix this? I just bought one so hopefully iy does what do yall think
 

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sounds like there is a wire crossed what seems to be happening is your brake lights are sending 12 volts directly to the brakes either your truck plug is wired incorectly or your trailer plug is what style of plug do you have (4,6,7 pin)
 

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Sparkplugs Not Required
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With a 99.5, you don't have a factory trailer brake controller. You definitely have wires crossed, supplying 12volts to your brakes. I would bet if you checked the lights, they aren't correct either. Sounds like the brake lights are connected to the brake actuation circuit.

Whenever I have ever bought a used trailer, I have had to trace all of the wires.....you can't believe what kind of cobbled mess some people have made with them. Also, there should be a diagram of the truck's plug in the owner's manual.....

Good luck!
 

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International Threat
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Mine did the same thing until I installed a brake box.
 

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Get your test light out and pin the truck first. After you find the trucks plug is correct(hopefully). Start tracing out the trailer wiring to make it match the truck.
 

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Discussion Starter #6
thanks guys!!
 
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