Hayes Trailer Brake Controller
- HA81742B
- Electric
- Proportional Controller
- Indicator Lights
- Hayes
- Up to 3 Axles
- Under-Dash Box
- Dash Mount
This proportional brake controller keeps towing simple with a straightforward design and user-friendly controls. Includes an LED indicator and a slide-bar manual override. Adhesive backing gives you the option of drill-free mounting.
Features:
- Brake controller activates your trailer brakes in proportion to your vehicle's braking action
- Automatically adjusts trailer's braking based on deceleration of tow vehicle
- Simple controls keep your settings within easy reach
- Gain setting lets you adjust the amount of power sent to the trailer's brakes
- Slide-bar manual override allows you to control trailer sway or stop in emergencies
- Deceleration sensor lever lets you adjust initial braking power and aggressiveness for smooth, safe braking
- Red LED indicator lights up when brakes are engaged
- Quick, simple installation with included bracket and hardware
- Drill-free installation option with included adhesive tape
- Optional universal wiring adapter (HA81789-HBC) sold separately for a plug-and-play installation
- Plug-in, vehicle-specific brake control adapter (sold separately) can be used to reduce installation time on certain vehicles
- -35-Degree to 90-degree mounting range - must be horizontally level
- Made in the USA
Specs:
- Application: trailers with up to 3 axles (6 brake assemblies)
- Compatible with electric brakes only
- Dimensions: 5-3/8" long x 3-1/4" wide x 1-3/8" tall
- Mounting angle: -35 degrees to 90 degrees vertically
- 5-Year limited warranty
Gain Setting for Braking Power
You can adjust the gain setting (also known as braking output) on the Hayes Energize III+ using the thumbwheel on the front of the module. This will set the maximum amount of power that will be applied to your trailer's brakes. You want to go as high as you can without the trailer brakes locking up. Typically, the gain is only readjusted when you experience changing road conditions or if you switch over from a heavy, loaded trailer to a much lighter, empty trailer, or vice versa. To get more power to your brakes, turn the wheel up. To get less power to your brakes, turn the wheel down.
![Hayes Energize III+ Braking Output]()
The red LED indicator on the front of the module will light up when the brake controller is activated. This way you can keep your eye on your braking and be sure that it's working.
Sensitivity Adjustment with Deceleration Sensor Lever
Once you have the overall power set, you can fine-tune the power output by adjusting the sensitivity of the internal sensor. This controls the aggressiveness of your trailer's braking, meaning how quickly the brakes reach the maximum braking level. You can adjust this when you're towing heavy loads and you need more umph to bring your trailer to a stop. Your tow vehicle doesn't need that much power to brake in time, but your heavy trailer does. Boost gets the braking power to your trailer brakes faster and with more intensity so that it doesn't push your tow vehicle forward. To increase the sensitivity for towing heavier loads, move the lever away from you. For a lighter load, move the lever toward you.
Slide-Bar Manual Override
The Hayes Energize III+ comes with a built-in, easy-to-reach slide-bar manual override, great for stopping sway or controlling your trailer's momentum in emergencies. To engage the manual override, just push the slide-bar to the left, toward the center of the controller. This will activate the trailer's brakes and brake lights without you having to apply the brakes on your tow vehicle, perfect for limiting trailer movement while you're cruising.
Quick, Simple Installation
The Hayes Energize III+ is easy to mount wherever you want it. Simply use the bolts or the double-sided tape to secure the included mounting bracket to your dash, and then install the controller in the bracket.
If your vehicle already has a plug-in brake controller wiring harness, just connect the unit to it. Otherwise, you will need to purchase a vehicle-specific wiring harness (sold separately) to plug into. If a harness is unavailable for your vehicle, hardwiring will be necessary.
Because the Hayes Energize III+ operates with an internal inertia sensor, it must be mounted between -35 degrees and 90 degrees vertically. The brake controller also needs to be horizontally level and parallel with the direction of travel to function properly.
![Hayes Energize III+ review]()
Installation Accessories
See etrailer.com's exclusive 7- and 4-way brake-control installation kit (ETBC7 - sold separately) if you don't already have a 7-way plug at the back of your vehicle
Note: One of the following will be required to ensure proper installation:
- 20-Amp circuit breaker (9506P - sold separately) for 2- to 4-brake applications
- 30-Amp circuit breaker (38630 - sold separately) for 6- to 8-brake applications
Proportional Braking
![What is proportional Braking]()
The Hayes Energize III+ brake controller comes equipped with proportional braking to give you the best towing experience. Proportional braking means that your trailer brakes mimic your tow vehicle's brakes. If you slam on the brakes in your vehicle, your trailer brakes will activate with the same intensity; if you brake lightly, your trailer brakes lightly too. The trailer's braking is in proportion to your vehicle's braking. This saves wear and tear on the tires and the brakes on both your vehicle and trailer.
The Energize III+ uses a pendulum system to sense how your vehicle is braking so it can send the right amount of braking power to your trailer. It detects the inertia of your tow vehicle and activates the trailer's brakes to slow at the same rate. The result is uniform braking across your towing setup. No push-pull action - just smooth, proportional braking every time.
81742B Hayes-Lemmerz Energize III Plus Brake Controller - 1 to 3 Axles - Proportional
Replaces 81741B and 81745
Installation Details
Alternate Instructions
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