Hayes-Lemmerz Energize III+ Electric Trailer Brake Controller - Proportional
Custom Wiring Adapter for Hayes Brake Controllers - Dual Plug

Part Numbers: HA81742B,HA81781-HBC

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Hayes-Lemmerz Energize III+ Electric Trailer Brake Controller - Proportional Under-Dash Box HA81742B
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Hayes-Lemmerz Energize III+ Electric Trailer Brake Controller - Proportional
part number: HA81742B

Energize III+ all electronic brake controller features a patented sensing device that automatically monitors and measures tow vehicle deceleration and applies the trailer brakes in direct proportion. It reacts instantly to any change in brake pedal pressure and ensures controlled, smooth stops. Trailer and tow vehicle stoplights operate automatically when the manual lever or trailer brakes are applied.

  • Proportional electronic trailer brake controller
  • Combines the best of the Energize III and XPC into one unit
  • Reduces inventory
  • 3 axis accelerometer
  • Faster/smoother stopping performance with extra power and control
  • Recommended for medium and heavy duty trailers with 2, 4, and 6 electric trailer brakes
  • Provides automatic and manual trailer braking
  • 100% braking power in manual mode
  • Featuring the exclusive Hayes Quik-Connect installation that you have come to rely on
  • Limited lifetime warranty
  • Wide range of mounting positions and pendulum adjustability
  • Easy to install mounting bracket and instructions included with VHB Tape for peel and stick installation
  • Trailer/tow vehicle stoplights operate when trailer brakes are applied automatically or with manual lever
  • Made in the USA

81742B Hayes Energize III Plus - Proportional

Replaces 81741B and 81745

Custom Wiring Adapter for Hayes Brake Controllers - Dual Plug
part number: HA81781-HBC

Install your Hayes electric trailer brake controller quickly and easily with this custom wiring adapter. One end plugs into the controller, and the other plugs into the junction box beneath your vehicle's dash.


  • Plug-in wiring adapter allows for quick, simple installation of your electric trailer brake controller
  • No cutting or splicing required
    • Custom connector end plugs into the electric junction box beneath the dash of your vehicle
    • Opposite end plugs into the back of your electric brake controller
  • Compatible with time-delayed and proportional brake controllers from Hayes
  • Made in the USA

Installation of Hayes Brake Controller Adapter

To install your Hayes electric brake controller, you need to connect the wiring of the controller to your vehicle. Certain auto manufacturers offer pre-wired options, typically known as tow packages, in which the wiring is run for you from the dash to the trailer connector on the back of your vehicle. Usually when this is done, a port is installed at your dash so that you can easily plug in a brake controller.

Junction BoxBrake-Control Adapter Port

This adapter plugs into the port that is built into the electric junction box underneath your vehicle's dash. The black box is located to the left of the steering column, just above the carpet. To plug in the adapter, first remove the cover on the box. The adapter plugs into the second slot from the left, on the top row.

No hardwiring is required to install this adapter. After you plug it into the factory port, you simply plug the other end of the adapter directly into your electric trailer brake controller. Because there are no wires to connect, installation is not permanent. You can unplug and remove your brake controller at any time to transfer it to another vehicle or securely stow it away.

81781HBC Hayes Dual-Mated Brake Control Wiring Harness - Chevrolet, GMC, Cadillac

Replaces 81781-HBC

Customer Reviews

Hayes-Lemmerz Energize III+ Electric Trailer Brake Controller - Proportional - HA81742B

Custom Wiring Adapter for Hayes Brake Controllers - Dual Plug - HA81781-HBC

Average Customer Rating:  4.9 out of 5 stars   (21 Customer Reviews)

Install your Hayes electric trailer brake controller quickly and easily with this custom wiring adapter. One end plugs into the controller, and the other plugs into the junction box beneath your vehicle's dash.

- HA81781-HBC
by: William06/29/2019
2001 Chevrolet Silverado

I was needing to install a brake controller in a newly-acquired 2001 GM pickup. The truck already had an available plug-in port, and I was looking for a connection cable between it and the controller. Due to their strong reputation for good business, I checked with eTrailer first. They not only had exactly what I needed, but the price was about the lowest around. I ordered the cable, and the shipping was fast. As expected, the cable fit perfectly, and was the precise length necessary. I have used this company before this order, and rest assured, I will do it again. 664464

- HA81742B
by: James08/04/2018

Very pleased with the Hayes controller and the installation videos and information available at etrailer. My installation was hardwired due to an earlier install which removed a connector, so etrailer support was very beneficial plus their price was very competitive...a winning combination. 549748

- HA81742B
by: Amanda07/31/2019

Easy to assemble and etrailer made sure that I had everything I needed to install the brake control system. Order arrived on time and will definitely order from etrailer again. 678721

- HA81742B
by: Nicholas09/22/2020

Works well! 887094

- HA81781-HBC
by: Tim08/24/2020
2002 Chevrolet Suburban

Very fast shipping, will buy from this store again, happy customer. 867944

- HA81742B
by: Dennis08/15/2020

super easy to install with the adapter. gain was set a tad high initially so be sure to turn it down first, then up until you get the gain you want. 862773

- HA81781-HBC
by: Alton05/25/2020

super fast shipping. definitely will use etrailer in my future needs 803211

- HA81742B
by: Howard04/26/2020

Easy installation 5 minutes 786566

- HA81742B
by: Harry03/07/2020

I installed it yesterday but did not have a chance to yet we moving on the 1st of next month what did 764207

- HA81742B
by: Quench03/03/2020

Very easy to install, easy to follow instructions. Works great. 762810

- HA81742B
by: Van T02/20/2020

works. what else is necessary? 756690

- HA81781-HBC
by: Billy11/05/2019
2001 Chevrolet Silverado

work well installed easy 722913

- HA81742B
by: Billy11/05/2019

with wiring harness installation was easy ...worked well 722912

- HA81742B
by: Richard10/23/2019

Got tip off Utube for the wiring harness adapter for a 2019 Ram. Installation was plug and play. We have a 26 ft camper we will be towing. Very easy install. 719795

- HA81742B
by: James10/07/2019

Exactly what I ordered. Easy to install 714370

- HA81742B
by: Ken05/31/2019

my second one in another truck, works well for my heavy race trailer 650873

- HA81781-HBC
by: Kenneth08/03/2018
2002 Chevrolet Suburban

Well made product that installed easily and great service! 549234

- HA81781-HBC
by: Jesus12/12/2017

Very good 459449

- HA81781-HBC
by: Greg12/05/2016

Easy hook up , works great . 322354

- HA81781-HBC
by: Mike06/21/2016

Every thing works great 263265

- HA81781-HBC
by: Eric H.06/02/2015

Along with wiring harness ordered a Hayes controller and a trailer jack. Was hoping for a Friday delivery. Items were setting on front porch midday Thursday! Once again outstanding service and products. 199809


Ask the Experts about this Trailer Brake Controller
Do you have a question about this Trailer Brake Controller?

  • How Does Hayes Brake Controller install in 2012 Volvo XC60
  • You will need to start with a 4-way (if you do not have one) installed on your 2012 Volvo XC60 to install a brake controller. For that you would want the # 118739 which I attached an install video for. From there you would need to convert the 4-way to a 7-way so that you can install the Hayes brake controller # HA81742B. For that you will want the Brake Controller Install Kit and 7-Way Adapter part # ETBC7. I attached installation instructions and an install video for this product as
    view full answer...

  • Brake Controller Wiring Harness for 2017 Ford Expedition
  • Not all manufacturers will utilize the same brake controller wiring harness. Hopkins, Tekonsha, Curt, etc, all have their own connections on the brake controller side and the vehicle manufacturers will have a specific connector if they are prewired for a controller as well. For instance the Hayes-Lemmerz Energize III+ Electric Trailer Brake Controller - Proportional # HA81742B will use the Custom Wiring Adapter for Hayes Brake Controllers - Dual Plug # HA81794-HBC for a 2017 Ford
    view full answer...

  • Does Install of Brake Controller in a Vehicle Affect Vehicle Brakes
  • The brake controller you sent in a picture of will only affect the brakes of a trailer you would be towing. It does not affect the brakes of your vehicle in any way if you were to leave the controller installed. I attached an FAQ article on brake controllers for you to check out as well.
    view full answer...

  • Troubleshooting Energizer III Brake Controller with no Power Output on 2009 Chevrolet Silverado
  • Yes, the signal for the trailer brakes comes from the stop light lead. The red wire on the controller is meant to be connected to the stop light circuit which is the light blue or orange wire on GM vehicles with the factory tow package. This wire will then send a signal to the brake controller when the brake pedal is pressed which in turn sends power to the trailer. I would first start off by testing the light blue stop light wire on your 2009 Chevrolet Silverado. You will want to use
    view full answer...

  • Red Light on Hayes Brake Controller Stays on and Drains Tow Vehicle Battery
  • I am not sure which Hayes brake controller that you have, but in reviewing the installation instructions for the Hayes-Lemmerz Energize III+ Electric Trailer Brake Controller # HA81742B I found that there is a section that goes over if the "Controller red indicator on all the time." The solutions they offer call for testing the Red wire and the Blue wire on the brake controller with a circuit tester like part # PTW2992. The Red wire connects to your Stop Light Switch and only receives
    view full answer...

  • Tips for Finding Brake Controller Stoplight Circuit Wire in Truck
  • All you need for the red wire of your brake controller is a circuit that sees voltage only when the brakes are applied. If you wanted to run a wire to the fuse box to find a wire like you said that would work fine. Some people will also use the third brake light circuit as well. It almost sounds like you are running the blue wire of the controller to the stop light circuit if the brakes lock up when you tap them. Or your brake controller is just set too aggressively. I attached a
    view full answer...

  • Can Hayes Energize III Install in 2001 Dodge Ram 1500 ST 4X4
  • For your 2001 Dodge Ram 1500 the Hayes Energize III part # HA81742B that you referenced can be installed if you use the install harness part # HA81782-HBC that you referenced as that is the custom fit harness designed for your truck.
    view full answer...

  • Trailer Brake Controller Manual Override Not Functioning but Trailer Brakes Work from Brake Pedal
  • Since the trailer brakes are working when you press on the brake pedal, it sounds like there could be one of two things going on here. It could be something as simple as the connections inside the controller being dirty or dusty. Give the manual override button a series of pushes and let the button snap back up into place- we just want to try to dislodge anything that might be keeping the button from making a full connection to the internal parts that operate the manual override. If
    view full answer...

  • Will Hayes Energize III Work on Tandem Axle Trailer with One Brake Axle
  • The Hayes Energize III brake controller part # HA81742B that you referenced will work great on a tandem axle trailer that has one brake axle. That means your trailer has two assemblies which is perfect with this controller.
    view full answer...

  • Hayes Blackbird Has Constant Power On Blue Wire Without Brake Pedal or Override Activated
  • Correct, if you have constant power on the blue brake output wire then your brake controller is faulty and will need to be replaced. The Hayes Blackbird Trailer Brake Controller part HA81726 is a timed delayed brake controller so this would be a great time to upgrade to a proportional brake controller which will be much smoother and will have a faster response time. The Hayes-Lemmerz Energize III part # HA81742B would be a good option for this and it uses the same plug and mount you have
    view full answer...

  • Brake Controller Connector Location on 2005 Dodge Ram 1500
  • If your 2005 Dodge Ram 1500 came with a factory 4-Way or 7-Way trailer connector at the rear then yes, there is an OEM harness under the driver's side dash and to the right of the emergency brake pedal. Typically this should be blue but the color could vary. If you don't have a factory trailer connector at the rear of your vehicle then you'll need to hardwire everything. The brake controller I recommend, if you don't already have one, is the Hayes-Lemmerz Energize III+ # HA81742B because
    view full answer...

  • Troubleshooting OC Error Message on Hayes Blackbird Trailer Brake Controller
  • When the Hayes Blackbird Time-Delayed brake controller displays the error code OC this means that the controller senses that it has lost its electrical connection to the trailer's brake circuit. This code could be caused by many things: trapped water, dirt or corrosion inside the vehicle socket or trailer plug, or it could be due to a loose physical connection at the 7-way or at the blue wire at the back of the controller. The blue wire carries the output signal from the controller to
    view full answer...

Info for these parts were:

Edited by:
Lindsey S
Updated by:
Laura H
Updated by:
Sarah W
Installed by:
Cole B
Written by:
Tammy D

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