Towing a Trailer with Electric Brakes with a Semi Tractor with Air Brakes

Question

Question:

I see the air to electric brake controller. Do you have any products for converting the light control wiring from my tractor to my goose neck. I tried making my own convertion it works but interferes with the RF brake controller operation. Thanks towing an electric brake trailer with a semi tractor.

asked by: Ryan D

0

Expert Reply:

To tow your trailer that uses an RV style 7-way blade style connector with your semi that has a 7-pin connector, you need to construct an adapter that will also combine the brake signal into the right and left directional signal pins.

This can be done by using a female 7-pin socket # PK11720 to accept the plug from the semi, a tail light converter # 119178 and a female 7-way RV blade-style socket # PK12-707E. The converter would be wired in between both sockets to combine the brake light signal onto the right and left turn circuits for the trailer. See the diagram I included showing how to wire this setup.

The Hayes air utility brake control # HA100400C you referenced will work as this controller taps into the semi air brake line and sends an electrical signal back to the trailer brakes when activated.

What I recommend and is easier to install would be to get a Tekonsha Prodigy P2 brake controller, part # 90885. Electric brake controllers do not tap into the vehicle braking system at all. They only need an input signal that tells it you are stepping on the brake pedal then it sends power back to the trailer brakes.

On the brake controller, the white wire needs to be grounded to the battery, the black wire connects to the positive battery terminal via a 30 amp circuit breaker, # PK54530, the blue wire goes out to the trailer connector and the red wire is input from the brake switch.

I included a few helpful articles and video review for you to look at.

expert reply by: Chris B

0

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Mark T.

3/17/2025

I need something to make my electric trailer brakes to work from an Semi air brake system. right now they lock up when I use an adapter for the 7 pin round connector on the truck to the 7 way flat connector on the trailer rv plug-in . . any ideas ? any list of items needed ? need help and fast

Reply

Jon G.

3/17/2025

@MarkT Have you tried the solution Chris mentioned above? In my experience, you'll need to make your own 7-Way plug for the RV just like what this page talks about. Adapters just won't work for a Semi to RV setup.

Reply

Answer 1

The trailer brakes work on a separate circuit than the lights. You have a couple of options to control the electric brakes on the trailer. One option is to use an air over electric brake control, #HA100400C. This unit connects to the air brakes on…

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Answer 2

The Tuson DirecLink Base Model Trailer Brake Controller - 1 to 4 Axles - Proportional #335DL-100 you were looking at for your 2013 Freightliner M2 112 pulling a Kaufman Wedge Car Hauler will be perfect. The 335DL-200NE you were looking at has…

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Answer 3

Yes, David you are correct. The Redarc Tow-Pro Liberty Brake Controller w/ Custom Harness item #RED82CR is exactly what you need. Since your 2024 Toyota 4Runner came with a 7-way connector, the plug and play adapter included with item #RED82CR will…

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Answer 4

If your trailer has separate turn signals from the brake lights and you want them to remain that way, you will need to use a special converter. On the trailer side, behind the 7-Way, you will attach the Vehicle to Vehicle Taillight Converter,…

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Answer 5

You'll want to look at the weight rating sticker at the front of your trailer for that info. On e of the numbers should say what the empty weight is of the trailer, one should say what the load capacity is, and one should have the…

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Answer 6

Since even semi trucks like what you have use OBDII connectors the Tuson DirecLink Base Model Trailer Brake Controller #335DL-100 that you referenced can be used. The module of this is what interprets the brake signal from your tow vehicle and…

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Answer 7

The globrite 122 in red or yellow/amber are 3.75 inches by 1.70 inches from what I can find online. We do not have a direct replacement, however the closest dimension we have to replace them is 3-1/2 by 1 inch. I recommend the #MC68RB and #MC68AB. If…

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Answer 8

Hey Ray, thanks for reaching out! The Tuson DirecLink Base Model Trailer Brake Controller #335DL-100 can definitely be used with your 2005 Freightliner Century Class either by splicing in the wiring or using one of the following adapters if they…

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Answer 9

Either way is correct. It depends on if you want to keep the semi-style 7-Way (if you need to tow that type of trailer) or if you will never be towing a semi-trailer. If you need to keep the 7-Way semi active on the truck, then you would need to make…

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Answer 10

For your Peterbilt 335 I definitely recommend going with the Tekonsha Prodigy P3 Trailer Brake Controller #90195 over the Hayes #HA100400C because it's going to allow for a much easier install and is more economically priced. The P3 also offers a…

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Answer 11

Thanks for reaching out, Keith! Semis have different functions for their wiring connectors so we'll essentially need to "start from scratch" using the following: - Universal 4-Way #119147KIT - Universal Upgrade #ETBC7 This gives you the…

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Answer 12

I do have an option but the Flash Solid Steel HD Adjustable 2-Ball Mount part #FA49-00-5925 doesn't have an pintle hook/ball adapter. Instead, you can use the Curt Adjustable 2-Ball Channel Mount part #C45926 which has similar specs and can be…

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