How are trailer brakes normaly wire to a truck. I belive that my truck already has the wire for them on it. I have two good size wires running the length of my frame that are taped off near my hitch. At the other end one runs to the junction box where the trailer harness hooks in to and the other looks like it is a ground that was cut because it is just laying there. With this system do i need a brake controler in the cab? How would i wire into the trailer it has four brakes on it?