How to Wire Electric Brakes on Gooseneck Trailer

Updated 08/18/2017 | Published 08/16/2017

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Question:

Hello. Not seeing my situation for assistance so sending question. I have a tandem axle gooseneck new, which has electric brakes on rear axle but wires have not been run forward to truck. There are two wires coming out of each hub on each side of the rear axle. The axles were painted so cant tell colors of wires but on one side both appear red and the other side they are either black or painted black. Anyway they are just pigtailed out from the hubs about 4inch in length. The trailer currently is wired with a 4 way flat plug for turn signals, running lights for night and brake lights and assume back up although not tried back up at night as just got the trailer color of wires are black, white, yellow and green. I want to change to a round 7 pin plug and hook up the brakes. The truck is currently wired with a brake controller so no wiring is needed on the truck side. Wanting simple step by step of running wire from brakes forward. I can handle from a wiring diagram on your previous post how to connect all wires to the 7 pin trailer side plug. Just need help with integrating the trailer brake wiring recommended guage etc. Attached a pic of what the hubs look like with short wires coming from the hubs.

asked by: Frank B

Expert Reply:

Let's start at the brake assemblies/hubs on your new gooseneck trailer.

The two wires coming from each assembly look exactly as they should. One wire will ground to the trailer frame and the other wire will attach to the brake output wire. The fact that you do not know which wire does what is absolutely okay! This is because brake magnets do not have polarity, so either wire can be used for either function.

You will then need to run wiring from the front of your trailer to these trailer brake assemblies. You can use 10 gauge wire like # 10-1-1, which is sold by the foot. Start by running this wire from the front of your trailer to one of the brake assemblies. Connect this wire, which we will call the power wire, to whichever wire on the brake assembly that you did not attach to the trailer frame for ground. You can use butt connectors # 05732-2 to make the connections.

Then run another wire from the power wire on this brake to the brake on the other side of the axle. If you are able to run the wire through openings in the trailer frame, this is recommended, as it will better protect the wire from the elements. You can use zip ties like # DW05724-10 to secure the wiring as you route it along the frame.

For a 7-Way on your trailer, I recommend the Hopkins 7-Way Molded Trailer Wire Connector # H20046.

I have also attached an article on adding electric brakes to a trailer (which includes wiring) that you might find helpful.