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 Brake Controller - 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

Video of Hayes-Lemmerz Energize III+ Electric Trailer Brake Controller - Proportional

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for Hayes Brake Controller - Proportional Controller - HA81742B Review

Today we are going to be taking a look at the Hayes Enegerize III Plus. This is an electric brake controller. This proportional brake controller is for use on all trailers with 2, 4, or 6 electric trailer brakes. A proportional brake controller works in direct proportion to the tow vehicles braking effort, so basically the more deceleration detected by the internal censor, the greater the amount of power that is delivered to the trailer brakes. This offers faster and smoother stopping performance, as well as extra power and control. It activates immediately, so there is no pausing like when using time delay brake controllers.

It's going to provide automatic and manual trailer braking with 100% braking power in manual mode. This brake controller features built in safe guards that are designed to protect your vehicle and your trailer. Some of those safe guards, I'm going to mention 3 of them. The first one is that the trailer and tow vehicle stop lights will operate when the trailer brakes are applied automatically or manually with the brake controller. The unit has built in short circuit protection from trailer brake wiring and it's going to feature hazard flash immunity that prevents pulsing of the brakes when the flashers are activated on the tow vehicle when the controller is adjusted correctly. Now the unit is going to come with detailed installation instructions. They are going to help with the initial setup.

It's going to go through owner responsibilities and it's going to walk you through the entire process of getting the unit out of the packaging to fully installed in your particular vehicle. Now right here on the front of the controller, there is going to be a red LED indicator. This will illuminate from dim to bright when stopping and will return to dim when deceleration is no longer detected. When the tow vehicle brake pedal is released, the controller and the red indicator will be turned off. The units also going to feature a gain wheel, that's located right here, that allows you to increase or decrease the amount of power being sent to your trailer brakes. On this side of the unit, it's going to have a deceleration sensor lever, that's going to let you adjust the braking aggressiveness. Then right here also at the front, it's going to have the slide bar manual override, so the further the lever is moved, the greater the amount of braking power that's applied manually to the trailer brakes.

This operation is an independent circuit and overrides the gain wheel adjustment, to allow full braking effort whenever needed. The unit is going to come with your mounting bracket, as well as your installation hardware. It's also going to come with VHB tape, which stands for very high bonding. This tape is included for an easier installation. You just peel that off, stick it to the unit and then stick it to the mounting surface. It's also going to come with a cleaning pad, so that way you can effectively clean the mounting surface when you're mounting it with the VHB tape. It's going to come with the 2 installation options.

Hardware is included. Everything that you need to get it installed is included. The controller is a really nice design, pretty compact. We'll take some measurements here in a couple of minutes, but it does come with the installation bracket. On the sides you're going to have 4 anchor holes, or adjustment holes, so you can choose whatever one works best for your application. Now when it comes to mounting, it does offer a wide range of mounting positions and pendulum adjust ability. Mounting angles between -35 and +90 degrees can be accommodated by this controller. Please keep in mind that the unit must be installed so that it is parallel with the travel of the tow vehicle and the trailer. When it comes to the wiring, the units going to feature the Hayes quick connect wiring, that makes connecting and disconnecting the brake controller quick and easy. The wiring simply plugs into a vehicle specific wiring adapter. Now those adapters are sold separately, they are available at etrailer.com, so you can check out that option to see if a wiring adapter is available for your vehicle. If you don't want to use that wiring adapter, you can cut that off, expose the wires and you can use it as a hard wire application as well. A few measurement to go over with you real quick starting with the overall width of the unit. Edge to edge, we're looking at a measurement of about 3 1/4 inches wide. Taking a look at the length from back to front, that is going to give us a length measurement of about 5 3/8 of an inch. Then when it comes to the thickness, that's going to give us a thickness of about 1 3/8 of an inch. The product is also made right here in the U.S.A. That's going to do it for today's look at the Hayes Energized III Plus.

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   (15 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: 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: 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


- 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

- 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: 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

- HA81789-HBC
by: bill w03/26/2016

Fit good shipped fast thanks good peopl e. 241820

- HA81789-HBC
by: Brad03/03/2016

Product quality and function is every bit as good as expected. 239352

- HA81789-HBC
by: Bruce H05/31/2015

Very pleased with product. Better than the factory of same product. It arrived before estimated date and installation was easy. 199138

- HA81789-HBC
by: Dave W03/09/2015

etrailer.com delivered as promised. Fast friendly service. Product arrived quickly as was exactley what I needed. The how to video was spot on. Thanks, Dave W. 177657


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

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...

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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