4-Pin vs. 7-Pin Trailer Wiring

A simple guide to choosing trailer wiring for utility trailers, campers, boats, and trailers with brakes.

What is 4-pin trailer wiring?

A 4-pin connector is common for small utility trailers and light cargo trailers. It typically supports basic lighting: running lights, brake lights, and turn signals.

What is 7-pin trailer wiring?

A 7-pin connector is common for campers, enclosed trailers, boat trailers with brakes, and trailers that need auxiliary power or brake-controller wiring.

Which one should you use?

• Use 4-pin wiring for small, simple trailers without brakes.
• Use 7-pin wiring when the trailer has electric brakes, a battery charge line, reverse lights, or camper-style electrical needs.
• Confirm connector requirements on the trailer before buying vehicle-side wiring.