Changing Trailer 4-Way to 7-Way Connector to Eventually Add Electric Brakes

Question:

I having a hard time figuring out how to go from a 4 flat plug to a 7 pin round plug on the trailer side I have a yellow,green, and 2 brown wires and the white which I know is ground. Im also gonna eventually hook in trailer brakes what wire goes to what number on the 7 pin round plug

asked by: Adam R

Expert Reply:

To install a 7-way connector on your trailer that you will want to eventually add electric brakes to, there are just a couple of things you will need to install.

First you will want to remove the 4-flat connector on your trailer and install a 7-way plug like the Hopkins 7-Way Molded Trailer Wire Connector # H20046. I recommend using a junction box like # 38656 and 10 gauge wire # 10-1-1 (sold by the foot) to run the brake output circuit from the junction box to the brake assemblies you install. I have attached an installation video on this junction box so you can see exactly how it works.

Each brake magnet will have two wires coming from them. One of the wires will ground to the trailer and the other will attach to the brake output circuit. It does not matter which wire you choose for each function.

The wires coming from the existing 4-way connector on your trailer will be connected to the appropriate locations in the junction box, then the wires from the new 7-way connector will connect using the same locations. I have attached an image that shows the color wiring code on this 7-way connector and the typical colors and functions for trailer wiring for you to review. It is still best to use a spare 12V battery to test the trailer wiring in order to confirm the function of each wire.

I have also included a couple of articles on trailer wiring and brakes that you may find helpful.