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

Part Numbers: HA81742B,HA81794-HBC

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Hayes Proportional 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

Custom Wiring Adapter for Hayes Brake Controllers - Dual Plug
part number: HA81794-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 built-in port behind 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 built-in port behind 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.

This adapter plugs into the built-in connector behind your vehicle's dashboard. To access this connector, first locate the instrument cluster finish panel in the center of the dash, near the driver's side. Carefully pry the panel out and undo the locking tabs to remove the panel. Plug the adapter into the mating connector in the large gray housing behind the panel.

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.

81794HBC Hayes Dual-Mated Brake Control Wiring Harness - Ford

Replaces 81794-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

Custom Wiring Adapter for Hayes Brake Controllers - Dual Plug - HA81794-HBC

Average Customer Rating:  5.0 out of 5 stars   (10 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 built-in port behind your vehicle's dash.

- 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: Van T02/20/2020

works. what else is necessary? 756690

- HA81794-HBC
by: Ron12/28/2019
2019 Ford F-150

Etrailer was very helpful with all the info needed to buy the correct connecting cable for my Hayes brake control. Delivery was quicker than expected & of course the cable works as stated. Great job again! Thanks Etrailer! 734677

- 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

- HA81794-HBC
by: John06/29/2018

This harnress was exactly what I ordered. Very pleased as usual. I have to add that for a while I was sure that I had received the wrong product. Then I watched an Etrailer install video and realized that the plug in my truck had an adapter attached that had to be removed before the harness could be plugged in. 5 minutes later I was done and ready to tow. 528384

- HA81794-HBC
by: Budman08/15/2017

I, order wrong wire adapter by mistake, I called etrailer, and spoke to nice lady there and gave the number of the one I had ordered, she looked up what I needed and placed order while I was on the phone with her. Got the adapter and it was the correct one and works perfect. To help others Ford puts a hard shell in there wire to protect against short circuit, it has to be removed before you can plug any adapters into it. 420629


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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...

  • Does Hayes Brake Controller Install Harness # HA81794-HBC Fit 2016 Ford F-150
  • Yes, the Hayes brake controller install harness part # HA81794-HBC that you referenced is a confirmed fit for your son's 2016 Ford F-150. The most popular brake controller used with this harness is the Hayes Genesis part # HA81790.
    view full answer...

  • Which Hayes Brake Controller Install Harness Fits 2015 Ford E-450 Cutaway Chassis
  • The correct Hayes brake controller install harness that fits your 2015 Ford E-450 cutaway chassis is the part # HA81788-HBC and not the one you referenced as that fits newer models.
    view full answer...

Info for these parts were:

Edited by:
Lindsey S
Expert Research:
Jameson C
Installed by:
Cole B
Written by:
Tammy D
Updated by:
Sarah W

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