I am installing a brake control for my trailer and i am not sure if my range rover made provisions for pre-wireing? There are 4 wires coming out of control, there is a hot, a ground, a wire to sense breaking (comes off brake switch, and a wire to power trailer the brakes. My GMC had made provisions for this (pre-wired, 1 molex connector) does my 2004 Range Rover or do i have to wire it?