7-Way RV Trailer Connector Wiring Diagram | etrailer When wiring a trailer connector, it is best to wire by function, as wire colors can vary. We have an excellent wiring diagram on our website, I will provide you a link so you can look at it. If you are looking at the inside of the trailer connector where the wires mount to the terminals starting at the notch at the top and working clockwise:5/5(17)Brand: Draw-Tite Trailer Wiring Diagram – Lights, Brakes, Routing, Wires The trailer wiring diagram shows this wire going to all the lights and brakes. Also, it must connect with things (if included) that use the Aux Power and Back-up lights too. Some trailer builders just connect this wire to the frame, then connect the ground from all the other lights and accessories to the frame as well.