Trailer Wiring Diagrams | Offroaders Home Trailer & Towing Trailer Wiring Diagrams Trailer Wiring Diagrams. Offroaders Staff Editor Trailer & Towing. The following page contains information about trailer to vehicle wiring diagrams including: 7 Wire Trailer Circuit, 6 Wire Trailer Circuit, 4 Wire Trailer Circuit and other trailer wiring diagrams. Norstar Truck Beds and Iron Bull Trailers Norstar has built a reputation for providing truck beds and trailers that work as hard as you and can withstand your daily grind. Norstar Truck Beds and Iron Bull Trailers are built with the most rugged users in mind providing years of service to any owner. Check out our product lines to find the perfect Iron Bull Trailer or Norstar Truck Bed 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.