4-Flat Trailer Wiring Harness for Trailer Lights 40'

This listing is for the 40 Foot Boat Trailer Wiring Harness found on most Boat and Utility Trailers that do not utilize brakes. This Harness features the standard 4 flat, or 4 pin connector seen on standard trailers without brakes, where only the light function portion of the Harness is needed. Scotch Locks or Butt Connectors can be used to tie your Side Markers and Tail Light into the Harness without needing to splice the wire during installation.

This Harness uses color coded wires to send power to your Trailer's Lights and Brake functions, and uses the same White, Green, Yellow, and Brown wires that all trailer harnesses use. The Functions of these wires are: White (Ground Wire), Green (Right Turn), Yellow (Left Turn), and the Brown Wires Operate the Left and Right Side Running Lights (Clearance Lights). 

A 4 Flat is generally used on Trailers that do not have Brakes, or Trailers that utilize Electric Brakes and not Hydraulic Brakes. We do offer a similar 5 Flat Harness for Trailers with Hydraulic Surge Brakes. This 40' Harness is great for use on longer Trailers or for those looking to run their wiring all the way up the Pipe Lights without having to splice into the harness, possibly exposing the internal wires to moisture and debris. The ground wire is about 30" in length, and is designed to be installed using a self tapping screw or utilizing an existing screw located near the Tongue of the trailer towards the tow vehicle. 

Commonly referred to as a "Wishbone Style" Harness, this means this Harness is designed to be run down both sides of your trailer rather than having to jump from left to right when installing and wiring in your side markers. You simply run (1) Brown Wire, and (1) Yellow Wire down the Left side of your Trailer frame, and (1) Brown Wire and (1) Green Wire down the Right side of your Trailer.