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

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

Item # HA81742B

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Hayes Brake Controller - HA81742B
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  • Proportional Controller
  • Hayes
  • Electric
  • Up to 3 Axles
  • Under Dash Mount
  • Indicator Light
Call 800-298-8924 to order Hayes brake controller part number HA81742B or order online at etrailer.com. Free expert support on all Hayes products. Guaranteed Lowest Price and Fastest Shipping for Hayes-Lemmerz Energize III+ Electric Trailer Brake Controller - Proportional. Brake Controller reviews from real customers.


  • All Info
  • Reviews (1)
  • Q & A (7)
  • Videos (1)
  • Photos
  • Why etrailer?

Hayes Brake Controller - 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



HA81742B Installation InstructionsInstallation Details HA81742B Installation instructionsHA81742B Installation InstructionsAlternate Instructions HA81742B Installation instructions


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

Average Customer Rating:  5.0 out of 5 stars   (1 Customer Reviews)


- HA81742B
by:

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


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


  • Recommended Electric Over Hydraulic Trailer Brake Conversion for Dual 10K Axles
  • The Disc Brake Kit # K2R1058D13 by Kodiak is the brake set that you will need to use for your 10,000 lb Dexter Torsion axles. When it comes to hardware, like the brake line, I recommend going with the Kodiak Hydraulic Brake Line Kit # 24TA-BLKIT which will wear better than other traditional brands. These lines are very flexible so the line is easy to maneuver under the trailer. The only downfall is that you cannot cut the line due to how hard and risky it is to do yourself. All you have...
    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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...


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Info for this part was:

Expert Research:
Jameson C
Written by:
Laura H
Installed by:
Cole B
Photos by:
Stacy F
Updated by:
Hannah L

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