Dodge Trailer Wiring Diagram 7 Pin | Free Wiring Diagram Variety of dodge trailer wiring diagram 7 pin. A wiring diagram is a simplified standard photographic depiction of an electric circuit. It shows the parts of the circuit as simplified shapes, as well as the power as well as signal connections in between the tools. Trailer Wiring Diagrams | etrailer Trailer 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.