Instructions to Wire a Trailer for Electric Brakes

Question

Question:

I have a black and white wire coming from the brakes, I dont know where to plug them in the box to truck lead, color for color

asked by: Larry B

0

Expert Reply:

It sounds like you are speaking of the wires for the brake magnets. If this is correct, you will need to connect one of the wires to the brake controller output wire on your trailer connector and the other wire will need to be grounded to a clean metal surface on the trailer. I have included a diagram for you.

expert reply by: Leah S

0

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Haden S.

6/1/2020

W/ a 4 wire harness (green, yellow, brown & white). How do you wire the electric brakes from the junction box to the hubs? Which wires Tie together to get function? I have 2 green wires coming from the hub, a red & black wire coming from the axle to tie into the passenger side brakes & the white & black brake wire. How do these all tie together from the junction box to get the brakes to function?? Thank you.

Chris R.

6/4/2020

If you just have a 4-Way connector harness on the trailer this needs to be upgraded to a 7-Way so you can wire up the additional brake functions. I recommend using the etrailer Kit # e99011 for this application, which includes the junction box and new harness.

Sam

5/26/2024

Hi Leah. Found this and it is super helpful. I just wanted to ask, my understanding is that there is no polarity as such with the electric trailer brakes. So any wire can be the ground. Can I ground any of the two to any suitable surface on the trailer frame?

Kevin C.

5/29/2024

@Sam Yes, either wire from a trailer brake assembly can be wired to power or ground, without issue.

Earl

5/23/2026

@KevinC. Is it better to ground thru a wire back to the plug??

Heather A.

5/23/2026

Most people ground through the trailer’s main ground wire that runs back to the plug, and then make sure the plug itself is properly grounded to the trailer frame on a clean bare metal surface. That usually gives the most reliable setup and helps avoid grounding issues caused by rust, paint, or weak frame connections.

Answer 1

That's a very good question, we tend to be extra cautious and say to use 10 gauge wire because that would be more than enough. When you get into longer trailers that will end up using a lot of wire the heavier gauge wire becomes more necessary.…

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Answer 2

Hey Drew, in theory yes you can hook an additional 7-way to the back of your first trailer that would get spliced into the trailer's current 7-way wiring and then the Redarc Tow Pro Link part #RED57AR would control both sets of brakes but you…

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Answer 3

Hey Jon, yes you sure can! And it's not too difficult either. If your vehicle already has a 4 way flat on the back, you can just install the #ETBC7 which converts it to a 7 way to be used with trailers that have electric brakes. Basically the 4…

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Answer 4

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…

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Answer 5

Hey J.J. welcome back! The Correct Track Trailer Alignment and Lift Kit item #RR55QX is exactly what you need to lift your tandem axle 5th wheel trailer. This kit comes with all the necessary brackets and hardware to lift your trailer the full…

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Answer 6

The brake wire providing voltage is wired in parallel, with one lead from each magnet being grounded to the trailer frame. We have a great Wiring Help Page that shows a diagram, I will provide a link to it below.

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Answer 7

In order to install electric drum brakes on your Top Hat Econo Angle Utility Trailer you will need braking assemblies, hub/drums, a breakaway kit, and trailer wiring. For the braking assemblies, I recommend using the Dexter Nev-R-Adjust Electric…

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Answer 8

The correct brake controller install harness for your 2018 Ford F-450 is the part #22292 and there is two possible locations for where to find the connector on your truck. Most of the time it's below the dash behind the steering column. The other…

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Answer 9

When converting from a surge braking system to an EOH system, you will want to have a fixed coupler. If you were to use the surge coupler as is without immobilizing, it can lead to rapid wear on internal parts because of the unassisted movement.…

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Answer 10

In order to actuate the trailer brakes, you'd need a brake controller installed in the vehicle and a 6 or 7-way trailer connector. A 4 pole flat wiring harness like the #18002 you'd looked at carries 4 circuits- right turn/brake lamp, left…

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Answer 11

On the Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector, #30717, the extra wires can be taped off, tied up with a cable tie, and tucked out of the way if not in use. I would attach the white ground wire to an existing grounding point or the…

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Answer 12

Hello Greg, thanks for reaching out. The Redarc Tow-Pro Link Bluetooth Brake Controller #RED57AR will work great on your 2026 BMW X5 X40i with the factory tow package. We list it for vehicles without the tow package since it comes with a universal…

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Instructions to Wire a Trailer for Electric Brakes

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