Trailer Wiring Diagrams | etrailer PDF fileTrailer Wiring Diagrams Trailer Wiring Connectors Various connectors are available from four to seven pins that allow for the transfer of power for the lighting as well as auxiliary functions such as an electric trailer brake controller, backup lights, or a 12V power supply for a winch or interior trailer lights. Trailer Wiring Diagram – Lights, Brakes, Routing, Wires The following trailer wiring diagram(s) and explanations are a cross between an electrical schematic and wiring on a trailer. We recommend these standards because they are pretty universal. That said, for specific situations, there are industrial standards with different connectors and wire arrangements. Electric Trailer Brake Wiring Schematic | Free Wiring Diagram Assortment of electric trailer brake wiring schematic. A wiring diagram is a streamlined conventional pictorial representation of an electric circuit. It reveals the parts of the circuit as streamlined forms, as well as the power and signal connections in between the gadgets.