4 Flat Trailer Wiring Diagram | Wiring Diagram 5 Pin Trailer Wiring Diagram Unique 7 Way Plug Wiring Diagram – 4 Flat Trailer Wiring Diagram. Wiring Diagram consists of several in depth illustrations that present the relationship of various things. It consists of directions and diagrams for various varieties of wiring techniques along with other things like lights, windows, and so on. 6 Way Plug Wiring Diagram/page/4 | Wiring Diagram 6 Way Plug Wiring Diagram/page/4 7 Way Trailer Plug Wiring Diagram Dodge. February 10, 2019 April 12, 2020 Trailer Wiring Diagram and Installation Help - Towing 101 Custom wiring is the ideal solution for installing trailer light wiring on your vehicle. A custom wiring harness or 'T-connector' is a vehicle-specific harness that plugs in without any spicing required and provides a standard connector output, such as a 4-way flat.