air brake -wiring a brake controller

[frank]

can anyone tell me where to look for the brake tie-in wire/switch location would be . hooking up a brake controller for a unified brake control system. my m/h didnt come wired for a control. the person that i bought the m/h from towed a car without a brake hook up so theres only a flat four pin connector at the hitch that i think is just tapped in to the motor homes brakelight wires at the rear. this would be the first hook up that i done with air brakes. has anyone done a hookup on there unit similar to this .thanks