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

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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

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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.

Reply

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.

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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?

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Kevin C.

5/29/2024

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

Reply

Answer 1

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 2

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 3

Hey Jared, If your axle has a brake flange like I have pictured below then you would be able to mount a 3,500lb brake assembly #AKEBRK-35 (manual-adjust) or #AKEBRK-35-SA (self-adjust). You'll also need to replace your idler hubs with drums so…

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Answer 4

To determine the size of the brake assemblies you need you have to measure the depth and width of the hub drum on the axle like what you see in the picture I attached. The most common size is 2-1/4 inch wide like the #T4071600-500 that you…

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Answer 5

Hey Steve, thanks for reaching out. So all of the 3,500 lb brake assemblies we offer use a standard 4-bolt mounting flange. The center on center horizontal measurement of the mounting bolts are 2-7/8 inches and diagonal center on center of 4 inches.…

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Answer 6

The left side is the driver side, right side is passenger side. On a trailer brake assembly like #23-105 the arm that the magnet is on points to the front of the trailer and the magnet always will be on the bottom. I have included a picture that…

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Answer 7

The 4 bolt brake mounting flanges are used on axles up to 3,500 lbs. If the axle is any larger then it will likely use a 5 bolt flange. There is one exception to this which is select 4,400 lb axles. That said, you cannot use 4 bolt brakes with 5 bolt…

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Answer 8

To install a Redarc Tow Pro Liberty in your 2023 Toyota Tacoma Sport you will need the following parts: Redarc Tow-Pro Liberty Brake Controller item #RED24FR Plug-and-Play Wiring Harness for Redarc Tow-Pro Trailer Brake Controllers item #RED99FR…

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Answer 9

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 10

I sure can Bob and thanks for the information! Since you have a Lippert 3,500 lbs axle you'll be able to use the Easy Grease Trailer Hub and Drum Assembly for 3.5K Axles item #AKHD-545-35-EZ-K, you were looking at. These have a 5 on 4-1/2 lug nut…

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Answer 11

To completely rewire your 20' trailer from start to finish I recommend using the following parts: 7-Way Connector and Cable - Hopkins Molded Cable 8' Long item #H20046 Junction Box - Trailer Wiring Junction Box - 7 Color Coded Terminals item…

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Answer 12

If things start to melt when you pull the breakaway pin from the switch then that indicates a bad short that we have to track down. It also sounds like somehow the trailer running light circuit is being tied into the brake and breakaway system wiring…

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Instructions to Wire a Trailer for Electric Brakes

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