7-Way RV Trailer Connector Wiring Diagram | etrailer 7-Way RV Trailer Connector Wiring Diagram. 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. I recommend using a circuit tester like part # 40376 to verify your connections.Wiring · Trailer Parts Trailer Wiring Diagram and Color Chart - ThoughtCo Each connects to a different function: Brown wire to the tail or parking lights. Green wire to right turn signal/brake light. Yellow wire to the left turn signal/brake light. White wire to common or chassis ground.