7 Pin Trailer Wiring Diagrams. Below are the 7 pin trailer wiring diagrams for each of the three main types of trailers. Even if your wiring color codes do not match up with that of the universal color coding listed earlier, the functions of each of the wires (regardless of color) will still match up with the same pins in the wiring diagram.. This trailer wiring guide comes complete with a color coded trailer wiring diagram for each plug type, including a 7 pin trailer wiring diagram, this guide walks through various trailer wiring installation solution, including custom wiring, splice-in wiring and replacement wiring. If your vehicle is not equipped with a working trailer wiring harness, there are a number of different solutions.
Mounting Your Trailer Wiring Harness Often the 4-pole trailer connector will remain in the trunk or cargo area of a car or SUV when not in use. This helps to extend the life of the connector by protecting it from the elements and accidental damage. When it is needed for towing, simply pull the connector out and shut the trunk or rear door.. Before connecting any wires, it's crucial to understand the wiring diagram for your boat trailer plug. This diagram will show you the correct pin placement and color coding for each wire. Make sure to carefully study the diagram and familiarize yourself with it before proceeding. 3. Prepare the Wires