The 4 way system is designed so the right brake light wire and right turn signal are green. Some problems such as a burned out bulb or a bad trailer light ground wire can be a snap to fixothers can be a real pain to diagnose and repair.

Boat Trailer Wiring Harness Considerations Partsvu Blog
How to wire a boat trailer lights diagram. Be sure to check with your local law. This video will provide the color layout for a 4 flat connector and a source to get a wiring diagram. I hope it helps you. They also provide a wire for a ground connection. Video tutorial on how to wire trailer lights. Yellow and green are for left and right turns and braking.
You must check the trailer manual to see if the wiring is correct but normally the white wire is called the ground wire while the brown wire is used for tail lights. 5 way trailer wiring diagram allows basic hookup of the trailer and allows using 3 main lighting functions and 1 extra function that depends on the vehicle. Properly functioning trailer lights are a must for safety so check your lights every time you use your trailer. The rest of the wires are wired from below. How to wire trailer lights. Below is a simple wire diagram for a standard four wire light harness.
Follow the steps in our photo sequence to keep your trailer lights in tiptop condition. The white wire ground on the following boat trailer wiring diagram is drawn in grey so that you can see it against the white background. 5 wire trailer wiring diagram. How i rewired my trailer. The four wires control the turn signals brake lights and taillights or running lights. The places to check grounds are as follows.
Though trailer lighting systems are available in an array of configurations the most popular is the 4 way system. 4 way trailer connectors are typically used on small trailers such as boat snowmobile utility and other trailers that that do not use brakes. 4 way trailer connectors are. If a ground problem exists it will show at this point. So here i have an older trailer which needed some work along with re wiring the lights. Start by cutting the white wire and attaching it to the trailer frame.
This is a fairly simple setup no license plate light or clearance lights. As the name implies they use four wires to carry out the vital lighting functions. The connector on the tow vehicle should have a ground wire secured tightly to a clean unpainted surface on the frame. Some trailer builders just connect this wire to the frame then connect the ground from all the other lights and accessories to the frame as well. The trailer wiring diagram shows this wire going to all the lights and brakes. An extra pin allows using another extra function.
When the taillights and brake lights are used at the same time it creates the maximum amp load of the lights on the trailer. It is referred to as such as the system needs a mere four wires for the trailer tail lights turn signals and brake lights to illuminate. Poor ground connection to the trailer frame is a common problem with lights that dont work. Also it must connect with things if included that use the aux power and back up lights too.