How to Wire Electric Brakes on a Tandem Axle Trailer
Question:
Installing new trailer brakes on a tanden axle trailer.When wiring my understanding is that the existing 7 pole wiring can be tapped into by running a two wire 12 guage section from brake to brake and then splicing into the existing 7 ptong and attaching the blue and whiteground wires.Do i have to ground the white wire to the trailer ? Thanks
asked by: Gene L
Helpful Expert Reply:
If your trailer has 7 wires running all the way back to the brakes, then yes, you can tap into the existing wiring. Each of your new brakes will have two wires for the brake magnet. One wire is for 12 volt power to the brake magnets and the other wire should be grounded either to the trailer frame or to the main trailer ground wire. It does not matter which wire is used for power or ground because they are not polarized.
If the trailer wiring is running down the left side of the trailer, then we splice the left side brake assemblies into the main electric brake power wire coming from the 7-way connector. We then run a jumper wire from the electric brake power wire to the right side brake assemblies (see photo).
I recommend using 12-gauge wire, # 12-1-1, for the jumper wire and for additional ground wire. If you want to use duplex wire, you can use part # 10-2-1.
I have attached an electric brake installation video for you to check out. The trailer in the video is a single axle trailer, but it will give you an idea on the installation process.
Mike B.
6/11/2020
I am having a brake problem on my TT. I keep getting a message in the truck that the trailer brakes have disconnected. it is intermediate. I disconnected the blue wire and ground wire for the brakes and tested each to ground. I have continuity on the blue wire to ground with the brake ground wire disconnected. This does not seem normal to me. What is your opinion?
Products Referenced in This Question
Deka Jacketed 2 Wire, 10 Gauge, Brake Wire - per Foot
- Wiring
- Wire
- Jacketed Wire
- 2 Wire
- 10 Gauge
- Deka
more information >
Product Page this Question was Asked From
35 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 42" Ground
- Trailer Wiring
- Trailer Connectors
- Trailer End Connector
- 31 Feet and Longer
- Plug and Lead
- 4 Flat
- Optronics
more information >
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Matt
2/23/2020
Bought a tandem trailer with brakes on one axle. Axle tube has 2 wires coming out on both left and right sides. Are these suppose to be connected to the brakes on their respective sides? What is the wiring diagram? Never seen wires coming from inside axle.