By law, trailer lights must be connected into the tow vehicle's wiring system to provide trailer running lights, turn signals, and brake lights. This is accomplished by tapping into the tow vehicle's electrical harness to transfer power to the trailer wiring system. Connectors are used between the two to allow disengagement when not towing.
Various styles of connectors are available with four to seven pins to allow transfer of power for the lighting as well as auxillary functions such as electric trailer brake controls, backup lights, etc. Choose a connector that has the number of pins for the functions required. The male end is mounted on the tow vehicle side and the female terminal on the trailer side.
Trailer Wire Size
Recommended Minimum Hookup Wire Size (Copper)
- 2 brakes, 12 AWG
- 4 brakes, hitch-to-axle distance under 30 feet, 12 AWG
- 4 brakes, hitch-to-axle distance 30-50 feet, 10 AWG
- 6 brakes, hitch-to-axle distance under 30 feet, 10 AWG
- 6 brakes, hitch-to-axle distance 30-50 feet, 8 AWG