How To Have Both A 4-Way Flat And 7-Way Round Connector On 3,500-lb Utility Trailer

Question:

I have a 3,500 lb pound capacity utility trailer that I am adding electric brakes. I would like to retain the 4 way flat plug for vehicles that don't have a 7 round connection, and are not hauling heavy loads, so they won't necessarily need the brakes on the trailer, only lights. Can I splice the 7 round wiring into the existing light wiring, and have both the 4 flat and 7 round connectors on my trailer? If so, what is the best way to wire the ground from the 7 round loom in to the lights and brakes?

asked by: Edd G

Expert Reply:

To make things cleaner and easier, I recommend getting the Trailer Wiring 7-Way Upgrade Kit, Item # HS381-9000. This kit will include a 7-Way trailer connector, junction box, wire loom, and hardware. You will make the connections for each circuit through the junction box which will also give you a cleaner look and install.

You will run wiring from the front of your trailer and the junction box to your trailer brakes. You will connect each wire function to function. To keep your 4-Way Connector option, you will need to splice these wires into the similar function wires running to the junction box. For your ground, you can splice everything together with the junction box ground.

After you have everything wired, you will need to add a brake controller to operate your brakes and I recommend the Tekonsha Prodigy P3 Trailer Brake Controller, Item # 90195, if you need one. The P3 is one of our most popular brake controllers, is flexible and easy to use, and has a proportional braking system with 3 boost levels.

You will also need a breakaway kit and I recommend the Pro Series Push to Test Breakaway Kit with Charger, Item # 50-85-315.

expert reply by: Brint H