currently i run a single axle 3500# 6x10 trailer. however i've added a new 60"Z and need to get a larger trailer. My current tow rig is a dodge ram 1500 with a standard 4pole flat trailer wiring hookup. I want to add an inertia brake controller when i get my new trailer. I'm not that familiar with electronic trailer brakes, how exactly is it going to hook-up. does this mean i'll have to replace my current trailer harness, or does it mean just adding another set of wires for the brake controller?