Hayes-Lemmerz Energize III+ Electric Trailer Brake Controller - Proportional
Universal Wiring Adapter for Hayes Trailer Brake Controllers

Part Numbers: HA81742B,HA81789-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

Universal Wiring Adapter for Hayes Trailer Brake Controllers
part number: HA81789-HBC

Designed for applications that do not come equipped with a brake control wiring harness port from the factory, this adapter plugs into your Hayes electric trailer brake controller at one end and the other end splices into your vehicle's wiring.


  • Universal wiring adapter provides a quick-disconnect for your electric trailer brake controller
    • No need to cut the plug off the brake controller to wire it directly to your vehicle
    • Makes it simple to plug and unplug controller for use in a different vehicle or for storage when you're not towing
  • Wire end splices into your vehicle's wiring
    • Use on a vehicle that does not have a factory tow package or is not equipped with a plug-in port
  • Connector end joins with the plug on your electric brake controller
    • Compatible with time-delayed and proportional brake controllers from Hayes
  • Wire length: 24"
  • Made in the USA

Installation of Universal 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. However, if no port is present, you will have to splice into your wiring.

With this universal adapter, you can install your Hayes brake controller without having to wire the controller directly to your vehicle. If your vehicle has a factory tow package, just splice the pigtail end of the adapter into your vehicle's factory brake control harness wiring, and then plug the other end of the adapter into the controller. If your vehicle doesn't have a factory tow package, you'll have to hardwire the pigtail end of the adapter into your vehicle's wiring. Because only the adapter is hardwired to your vehicle, you can unplug and remove your brake controller at any time to transfer it to another vehicle or securely stow it away.

If your vehicle is not equipped with a factory tow package, you will need to purchase additional equipment to ensure that the signals from your brake controller are sent to your trailer's brakes. We recommend etrailer.com's exclusive 7- and 4-way brake control installation kit (ETBC7 - sold separately).

81789HBC Hayes Universal Pigtail Brake Control Wiring Harness

Replaces 81789-HBC

Customer Reviews

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

Universal Wiring Adapter for Hayes Trailer Brake Controllers - HA81789-HBC

Average Customer Rating:  4.8 out of 5 stars   (29 Customer Reviews)

Designed for applications that do not come equipped with a brake control wiring harness port from the factory, this adapter plugs into your Hayes electric trailer brake controller at one end and the other end splices into your vehicle's wiring.

- 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: Art11/11/2020

Easy to install (with the adapter for my truck). Works perfectly. 910788

- HA81789-HBC
by: Nicholas09/22/2020

It took a while to figure out which wire to tap into for the brake signal, but we eventually figured it out. It takes some awkward body positioning to locate the wires above the brake pedal. 887095

- HA81742B
by: Nicholas09/22/2020

Works well! 887094

- HA81789-HBC
by: Ken K09/08/2020

Made trailer brake install easy. 875686

- HA81789-HBC
by: Homer08/21/2020


- 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

- 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

- HA81789-HBC
by: Quench03/03/2020

Makes installing trailer brake controller super simple. Great product. 762812

- 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

- 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

Great! No complaints.
Richard - 10/29/2020


- HA81742B
by: James10/07/2019

Exactly what I ordered. Easy to install 714370

- 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

- HA81789-HBC
by: Roger07/22/2019

Just traded car in for new one. Much easier to leave old cars wiring alone and add new plug to replacement car. 673514

- HA81789-HBC
by: James06/15/2019

The pig tail was easy to hook up. I was replacing a faulty unit so all the wires were handy. I did not want to do a hard wire in, this made it easy. 658645

- HA81742B
by: Ken05/31/2019

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

- HA81789-HBC
by: James11/07/2018

It's a plug and 4 wires. I haven't installed it yet but most likely it will work. It would have been nice if they had the vehicle-specific cable for their brake controller but then maybe my vehicle doesn't have a receptacle (2006 Jeep Commander). Not sure yet, haven't got that far, don't know when I will. I wanted to do it yesterday but it's been cold and rainy here and I don't have room in my garage to work so I've been working on the Jeep in the driveway. I got the trailer hitch mounted the other day and now I'm working on the wiring for the trailer plug. I put the Jeep up on 4 ramps to give me room to get under it and run wiring. At 275 pounds I need the extra space. When the rain stops and the wind dies down I will make an attempt to install this device, but I got this email first asking me for a review and an opinion. I don't really have an opinion yet and I can only write a review of what I know so far, which is very little. The instructions that came with it are quite simple. They tell you to plug it in and then read the instructions that came with the controller that you plugged it into. I was hoping for something more specific, like where should I look for the signal from the brake pedal to the stop lamps. I guess I'll start at the pedal and look for a place to tie in. Maybe YouTube has a video demonstrating the installation procedure for the controller using this Wiring Adapter. That would be nice too. The price for the item was fair, as was the shipping cost and delivery time. No complaints with any of that. I'd share a picture of the product but actually there's one on the page where it is advertised, the page from which I ordered it. I'm not sure why they want me to "share a picture of my product". As for the problem that it solved for me... I didn't have one. It solved that problem. Now I have one. 580967

Thank you for your review. There is not a port to plug a brake controller adapter into on the 2006 Jeep Commander. If the 2006 Jeep Commander has a factory towing package the wires for a 7-way will be ran to the front of the Jeep. You will then use the hardwire adapter part # HA81789-HBC
Universal Wiring Adapter for Hayes Trailer Brake Controllers
to splice into those wires. You will also need part # 5506 to complete the wiring to the battery. If the 2006 Jeep Commander does not have a factory towing package it requires the 7-way plug to be hardwired. In this case an wiring kit part # ETBC7
Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires
is needed. The ETBC7 comes with the all of the necessary wiring to wire in the plug and the brake controller. If the vehicle does not have a factory towing package you may also need a 4-way flat connector if you do not already have one. The 4-way connector is part # 118408
T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
for the 2006 Jeep Commander without towing package. I have attached a video of installing a brake controller on a 2010 Jeep Commander with factory wires ran and a help article for the ETBC7 installation.
-- Heather A - 11/08/2018


- HA81789-HBC
by: Jack P.01/20/2017

This product makes installing the brake controller so much easier, because I use this unit with multiple tow units it is nice to be able to unplug and move to the other vehicle. 333930

- HA81789-HBC
by: Jon01/10/2017

Came quick, just as ordered. 334694

- HA81789-HBC
by: DAVE12/22/2016

Works great with the Hayes brake controller. Makes older vehicle installation a breeze. 327406

- HA81789-HBC
by: Jerry M06/30/2016

Product arrived in good condition packaged very well as always great service and quick response.Will be buying from E-trailer again. Was able to find a replacement connector for my Hayes brake controller. Thank you keep up the good service. 266706

- HA81789-HBC
by: Bob P.04/10/2016

Made the installation a breeze and allows for the plug and play of the controller when I need it as opposed to the permanent installation of a brake controller in my other pickup. 243612

Show More Reviews

Ask the Experts 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...

  • Available Brake Controller to Fit a Honda Goldwing Towing a Tent Trailer
  • I found a brake controller for your Honda Goldwing and tent trailer application. The Hayes Blackbird Brake Controller and Universal Wiring Adapter, # HA81789-HBC, are the controller and harness I recommend for your application. The Hayes controller is a time-delayed controller that will allow set and adjust the power output to a preset intensity. You will use the Universal Wiring Harness to wire the controller to your bike and trailer. I have attached an article that will show the typical
    view full answer...

  • How to Install and Remove the Connector on Hayes Universal Wiring Adapter # HA81789-HBC
  • The Hayes Universal Wiring Adapter # HA81789-HBC that you referenced is intended to plug into the back of a compatible Hayes brake controller such as their Genesis # HA81790 and then hard-wire to your vehicle using the 4 wire leads. The plug portion on the adapter is not intended to mate with any connectors on your 2007 Dodge Ram 2500 Pickup. There are other brands of brake controllers that do use adapters with plugs on both ends, one for the controller and one for the vehicle, such
    view full answer...

  • Wiring Adapter for Hayes Lemmerz Energize III Brake Controller on a 2012 Chevrolet Suburban
  • The adapter you are looking for is the # HA81789-HBC. This universal harness will need to be hardwire installed for your 2012 Chevrolet Suburban. Hayes does not offer a wiring harness that will plug into the brake controller port under the dash, if your vehicle has one. I have attached a Help Article on installing a brake controller on your vehicle for your convenience.
    view full answer...

  • Installing Hayes Energize III Brake Controller on 2012 Chevrolet Silverado
  • To install your Hayes-Lemmerz Engerize III 81741B in your 2012 Chevrolet Silverado, you will want to use the Hayes Universal Wiring Adapter # HA81789-HBC. This universal adapter will need to be hardwire installed for your Silverado. Hayes does not offer a wiring harness that will plug into the brake controller port under the dash, if your truck has one. I have attached a help article on installing a brake controller in a 2007-2013 Silverado for you. This help article will walk you
    view full answer...

  • How to Set the Right Power Output on a Brake Controller when Towing a Trailer
  • For any brake controller, including the Hayes Blackbird, the set up process is basically the same. You start by setting the controller to the mid point for power output. Then with the truck and trailer coupled together on level, dry ground, tow at about 20 miles per hour or so. Then apply the manual override on full (not the truck's brake pedal). If the trailer brakes lock up and skid, adjust the power down and do the test again. If braking is insufficient then adjust the power up and
    view full answer...

  • Trailer Wiring Harness to Install Hayes Brake Controller on 1996 GMC K1500
  • For the Hayes Energize XPC brake controller the wiring harness that connects into the wiring of your 1996 GMC K1500 is # HA81789-HBC. It needs to be hardwired into your truck with the black wire going to 12 volt power, white to ground, the blue goes to the rear of your truck to power the trailer brakes, and the red connects to the stop light switch which is the wire coming from the truck's brake pedal connector that is hot only when the pedal is pressed. You can test this with a circuit
    view full answer...

  • How to Wire the Hayes Blackbird Brake Controller to a 2009 GMC Sierra
  • I attached a picture that has a diagram that details which wire from your 2009 GMC Sierra gets wired to the Hayes Blackbird Brake Controller part that you referenced. You will also need the universal install harness part # HA81789-HBC that you also referenced. The red wire of your truck goes to the black wire of the controller. The dark blue wire of truck goes to blue of controller. The light blue or orange wire goes to the red wire of the controller. The white wire of the truck
    view full answer...

  • Recommended Stoplight Circuit to Install a Brake Controller in a 1979 Ford F150
  • You should be totally fine installing a brake controller in your 1979 Ford F150 by using the brake pedal switch as the stoplight switch for the controller. You will just want to find the circuit that only sees voltage when the brakes are applied and none when not and you would be fine. You would want to use a circuit tester like part # PTW2993. I attached an FAQ article on installing a brake controller from scratch that should be very helpful for you.
    view full answer...

  • Troubleshooting Brake Controller that Powers Off and On Constantly
  • It sounds like you have an intermittent short on either the power or ground wire of your Blackbird brake controller and it is constantly shutting off and powering on. Check the attachment point for the black and white wires of the controller to see if they are making a secure connection as it sounds like one of the wires is loose. I also attached a help article on brake controller installs for you to check out as well.
    view full answer...

  • Parts Needed to Install Hayes Blackbird Trailer Brake Controller in 1994 Chevrolet Blazer
  • To install the Hayes Blackbird Trailer Brake Controller in your 1994 Chevrolet S-10 Blazer you will use the following items in addition to the controller itself. You will need Universal Wiring Adapter # HA81789-HBC that plugs in to the back of the Blackbird and provides 4 leads for hardwired installation. You will also use our brake controller install kit # ETBC7 which includes a 7-way socket, wiring, connectors, circuit breakers, etc. - everything you need to install the Blackbird.
    view full answer...

Info for these parts were:

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

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