wiring brakes

[CG]

i bought a trailer from a friend. it has electric trailer brakes. he wired it up himself and discovered when he turned on the blinker the brakes went on and off. so to fix this he cut the wires. my 72 burb has one of those trailer brake things you see mounted under the dash. personally i have no idea how they work. it has a brake line that goes to master cyl. and then it has three wires. as you can see in the pic its only using two of the wires and those two are spliced into an orange and blue wire. the orange one is part of a ribbon wire, one orange one black. when it comes out from under the dash and through the firewall the orange goes to trailer harness. the black wire (the one in the ribbon with the orange) starts on engine side of firewall and is spliced with a fused red wire and the red meets the blue (that came from under the dash) on the other side of the fused link. from there it is one blue wire that goes to batt hot and the other end is on the trailer connector. whew, you following me? ok now my questions. why is that one wire not used? next one, each of my trailers 4 backing plates on the drums has two wires coming out of them. how do i wire them in? one side to the orange and one side to the black wires we were talking about? im going to go pick up my purchase from cheyenne10 and i want this thing to be working perfectly. i already have the rest of the wiring figured out. this brake thing is messing with my head...thanks for any help guys.

oops should have posted this in general...sorry

[Gordo]

Of the three wires coming out of the controler, one will go to a good ground, preferably the neg battery post, another will be your 12V supply coming from the pos battery post with a 20 amp circut breaker for protection and the last one will be the power wire that feeds the trailer brakes, with a 4 wheel trailer brake set up that wire should be a mininum 12 gauge. The two wires coming out of each backing plate, one will be a ground and the other is the power wire. You can connect all four power wires into one and connect it to the proper terminal at the trailer plug. Connect all ground wires into one, attach it the the trailer frame then to the proper terminal at the trailer plug. The trailer plug outlet on the truck needs to have the ground terminal attached to the truck's frame. All grounds need to have a good clean metal to metal contact. I would also recomend soldering all joints and using heat shrink tubing and/or "liquid tape". There is also a standard sequence for the connections at the plugs so that you can interchange trailers/equipment without having to rewire. Hope this helps!

[CG]

on the backing plates there are two wires coming off each through a sort of grommet thing. both wires are the same color and neither is marked pos or neg. does it matter which is which? all im doing is completing a circuit arent i? so i would think it doesnt really matter which side pos or neg was as long as i dont have two pos or two negs? thanks gordo for taking the time i appreciate it. ive searched online and havent found an answer to this question.

[Gordo]

Right, attach those wires in any order as long as you have a neg and pos on each, they power up an electric magnet. The wires feeding the truck side and trailer side of the trailer plug should have a brown wire for tail lights, green wire for right signal and brake light, yellow wire for left signal and brake light, the ground wire could be white or black and the common color for the trailer brake wire is blue.

[CG]

thanks again all the info is much appreciated.