2000 f250 trailer brakes

Hello, I have a 2000 f250 sd 4x4 crew cab. The previous owner had an electric trailer brake wired but no controller in it. I installed a controller, used one but it worked in the truck it came out of, and rewired the truck because the existing wire was to small guage. everytime i touch the brake pedal it blows the inline fuse instantly. I've doubled checked the wiring and it seems to all be correct. The connections at the pigtail are rusty. What could be causing my headache? If i also try the controller by hand it blows instantly also. Could the controller have gone bad? Thanks for the help.

Make sure your fuse is rated high enough. I think my controller is rated for 15 amp. Is it blowing with the trailer connected or anytime? If anytime, follow the wires to the back and make sure none have a break in the cover that is touching metal. If that seems ok, then it might be the socket that the trailer plugs into at the back of the truck. One of the wires might be to the wrong connection causing a short.
I got rid of my fuse. I went to the parts store and got a self-resetting 15 amp breaker. This way if there is a temporary problem, like the trailer doesn't ground back to the truck just right, the breaker resets itself and I don't have to worry about not having the right fuse.

Thanks, I'll check the socket connections. The fuse is a 30amp, thats what it called for. I ran new wire to the back so I know that is ok. Yes it blows right away whether the trailer is hooked up or not. Thanks again.