4 Flat Wire Harness | etrailer Wishbone-style harness features a 4-pole flat trailer-end connector. Ground wire is 3' long. Features: Provides simple, efficient method for rewiring your trailer with a 4-way flat trailer-end connector 2 Brown wires, one with the green wire and the other with the yellow, make up. Trailer Connectors. Trailer End Connector. 4 Flat. Wesbar. 20 Feet Long. Value 4 Wire Trailer Wiring: Amazon "Makes wiring your trailer a piece of cake" - by NW_OR_USA This 4 wire harness is easy to install and includes a separate brown wire for each right and left light. (Most harnesses only have one wire and require a splice to connect to the second light.) At 25 feet, it is plenty long for almost any trailer.