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.

Reply

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?

Reply

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

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 4

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 5

The kit you are looking for is the part #BRKH10B which is nuts and lock washers needed to install the brake assemblies part #AKEBRK-35-SA that you referenced. The nut size is 7/16-20.

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Answer 6

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 7

It sounds like you may have a 7-way trailer connector and a 4-way trailer connector on your truck and only a 4-way connector on your trailer. Is that correct? See the attached picture for examples of each. If this is the case, then this change will…

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Answer 8

First you will need to remove the old hydraulic equipment. Remove the surge coupler or actuator, remove all the lines, and finally remove the brake assemblies. If you have 10 inch diameter hub and drums, you may need to replace those as well. If you…

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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

Yes, the Dexter Nev-R-Adjust Electric Trailer Brake Kit #23-468-469 that you referenced can be used on a boat trailer. I know what you are probably thinking...and that dipping electric brakes in water when backing the boat down the ramp is a bad…

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Answer 11

It may be possible to change your studs from 9/16" to 5/8" so long as the studs are drive-in, and the length and knurl/spline diameter needs to be the same. For example, if your studs are 2-3/4" long and have a 0.69" diameter…

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Answer 12

There really isn't a particular maximum trailer weight that is used to determine when brakes need to be added to both axles of a tandem axle setup. While I do still recommend checking your local laws, I am also not aware of any general laws that…

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