Four Pin Trailer Wiring Install - Wiring Diagram & Info Wiring your four-pin trailer can be a challenge when you first do it, but it’s a simple do-it-yourself task. It gets complicated when you have trailers with more cables, and in this case, you need an adapter to make the connections. The first step in wiring your trailer cables is How to Wire Lights on a Trailer | Wiring Diagrams In this case, you will need a set of wiring taps and a pair of pliers. Trailer Wiring Diagram. To connect the electric system of your trailer to the vehicle, you will be using special connector. Above we have describes the main types of trailer wiring diagrams. Below is the generic schematic of how the wiring goes. 4 pin trailer wiring diagram5/5(2) Trailer Wiring Schematic 4 Pin | Trailer Wiring Diagram Find your Trailer Wiring Schematic 4 Pin here for Trailer Wiring Schematic 4 Pin and you can print out. Search for Trailer Wiring Schematic 4 Pin here and subscribe to this site Trailer Wiring Schematic 4 How to Wire a 4-Prong 240-Volt Twist-Lock Plug | Hunker Generator twist-lock plug wiring, for example, is no different than the wiring for a conventional four-prong plug with the same current rating. To understand how to wire a 240-volt plug, it helps to have an understanding of 240-volt electrical connections in general.