Trailer Wiring Diagram - Wiring Diagrams For Trailers 4-Way trailer connectors are typically used on small trailers such as boat, snowmobile, utility and other trailers that that do not use brakes. As the name implies, they use four wires to carry out the vital lighting functions. The four wires control the turn signals, brake lights and taillights or running lights. They also provide a wire for a ground connection. 4-way trailer connectors are Related searches for boat trailer wire diagram boat trailer wiring 5 wirestrailstar boat trailer wiring diagramboat trailer light wiring diagramteske trailer wiring diagramboat trailer electrical wiringtracker boat trailer wiring diagram