bing tracking image
  1. Tow Bar Braking Systems
  2. Brake Buddy
  3. Brake Systems
  4. Air Brakes
  5. Air Over Hydraulic Brakes
  6. Hydraulic Brakes
Brake Buddy Select 3 Portable Flat Tow Brake System - Proportional

Brake Buddy Select 3 Portable Flat Tow Brake System - Proportional

Item # HM39524
Our Price: $1,389.24
Tow Bar Braking Systems

Will this fit?

To see if this custom-fit item will work for you please tell us what vehicle you'll use it with.

Shipping Weight: 19 lbs
Add to cart
zoom in icon
slider vertical icon
zoom out icon
Comment field cannot be left empty.
Name field cannot be left empty.

Thank you! Your comment has been submitted successfully. You should be able to view your question/comment here within a few days.

Error submitting comment. Please try again momentarily.

Product Images

In Use/Installed

Customer Photos

Need help with installation?
Locate installers near me
This portable unit gets you smooth braking without a complex installation. Senses the RV braking and applies the brakes proportionally. Easy to swap between multiple towed cars: settings adjust for safe, even braking for any size car. Great Prices for the best tow bar braking systems from Brake Buddy. Brake Buddy Select 3 Portable Flat Tow Brake System - Proportional part number HM39524 can be ordered online at or call 1-800-940-8924 for expert service.
  • All Info
  • Reviews (258)
  • Q & A (0)
  • Photos

Brake Buddy Tow Bar Braking Systems - HM39524

  • Brake Systems
  • Air Brakes
  • Air Over Hydraulic Brakes
  • Hydraulic Brakes
  • Proportional System
  • Brake Buddy
  • Portable System
  • Recurring Set-Up

This portable unit gets you smooth braking without a complex installation. Senses the RV braking and applies the brakes proportionally. Easy to swap between multiple towed cars: settings adjust for safe, even braking for any size car.


  • Applies towed vehicle's brakes proportionally for comfortable braking
    • Measures motorhome's braking and activates car's brakes with same intensity
    • Prevents false braking with terrain-sensing technology
  • Lets you adjust force and sensitivity for smooth braking
  • Swaps easily between multiple towed vehicles
    • Requires a second vehicle kit (BB59SR - sold separately) for each alternate car
  • Adjusts easily to fit in almost any vehicle
    • Sits level for optimal performance thanks to adjustable feet
    • Clamps easily around almost any brake pedal
  • Allows you to control and monitor braking with handy wireless remote
    • Plug into 12V accessory outlet or use with AA batteries
    • Easily check readouts for potential problems
    • Change braking modes and settings from the cab of your RV
  • Gets ready to tow with 1-touch auto start
    • Removes excess vacuum pressure from your car's brakes
    • Checks braking system for errors
  • Keeps car's battery fully charged with 15-amp battery charge line kit


  • Compatible with hybrids and other cars with electric power-assist brakes
  • Dimensions: 19" long x 11-3/4" wide x 6-3/4" tall
  • Power draw at 12V: 15 amps
  • Range of adjustable feet: 1" - 4" tall
  • Power harness length: 36"
  • Weight: 12 lbs
  • 5-Year limited warranty

Do I Need a Braking System for Flat Towing?

A braking system is a must when towing a vehicle behind your motorhome. Without it, the weight of the towed car can create a safety hazard, strain your RV's brakes, and affect its warranty. Most states legally require a supplemental braking system, so if you don't use one and you end up in an accident (which is more likely since your RV takes longer to come to a full stop), your insurance and liability headache just doubled. You also won't have any breakaway system; if there's an accidental disconnect, there's nothing to bring your car to a stop.

Pros of a Portable System

First, this system is great for DIYers, since you can get the basic installation done yourself. There will be some minor wiring to do under the hood and in the cab, but that's as complicated as it gets.

Second, it offers you a lot of flexibility. It's easy to move from one toad (towed vehicle) to another - or, if you think you'll likely get a new car down the road, you can easily set the Select 3 up in your new toad.

How Does the Brake Buddy Work?

The Brake Buddy Select 3 uses a built-in inertia sensor to detect when your flat tow setup begins to slow down as you apply the brakes in your motorhome. The moment the system recognizes the change in momentum, the actuator will press down the brake pedal of your toad proportionally: at the same time, with the same intensity. Meanwhile, the terrain-sensing technology keeps the unit from activating when you go over bumps in the road, so it doesn't brake when it doesn't need to.

Compatible with Hybrids and Continuous-Power-Assist Brakes

If you're towing a hybrid or any car with continuous-power-assist brakes, all you have to do to be able to use the Brake Buddy is change the Braking Mode to Hybrid.

Setting Up the Brake Buddy Select 3

You'll be setting up this portable unit in your toad every time you flat tow, so it's designed to be easy to do. And because it's so adjustable, it fits in almost any vehicle on the market.

setting up the Brake Buddy Select 3

Step 1: Position the Brake Buddy

Shift the driver's seat back and set the Select 3 on the floorboard. It's important that the unit sits as level as possible so the actuator has enough leverage to effectively push down the brake pedal, so adjust the feet of the unit to suit your floorboard if need be.

how to adjust feet of Brake Buddy Select 3

Each foot can be adjusted easily by hand or with the included wrench. Twist it counterclockwise, pull it down to the right length, and then twist clockwise to lock it in place.

Quick Tip: It's best to remove your vehicle's floor mat before installation to keep the Brake Buddy from shifting.

Step 2: Attach the brake pedal clamp

Brake Buddy Quick-Lock Clevis

Next you need to get the clamp attached to the brake pedal with the Quick-Lock clevis. This adjustable clevis is designed to securely clamp onto the pedal regardless of its size or shape. Once you have the clevis fixed around the pedal, turn the lever to tighten it in place.

Step 3: Plug in and power up

Brake Buddy Select AutoStart

Plug your Brake Buddy into the connector you'll have installed under the dashboard and then press the Auto Start button. The system will automatically boot up to your saved settings and then check your brakes, pushing and releasing the brake pedal several times to remove built-up vacuum pressure from the brakes and prevent over-braking. It will also check for any connection errors. Then you're ready to flat tow!

Braking Power Settings

Brake Buddy Select Control Panel

The braking power settings control how intensely the Brake Buddy Select 3 applies your toad's brakes. When you are first setting up the Brake Buddy, choose the setting that's recommended for a vehicle of your toad's size:

Vehicle Type Recommended Braking Power
Hybrids 10 - 20 psi
Cars and Compact SUVs 25 - 45 psi
Small Crossovers 25 - 45 psi
Crossovers and Small SUVs 35 - 65 psi
Mid-Size Pickups 35 - 65 psi
Large SUVs and Pickups 45 - 75 psi

After selecting an initial setting, press the plus or minus buttons on the control panel to fine-tune the power. The setting should be enough that your toad gives a slight tug at your RV when you brake. On the right setting, you won't be at risk of damage from over-braking. Once you've set the braking power, it shouldn't need to be changed unless you tow a different vehicle.

You can also customize the sensitivity. This determines how aggressively you need to brake in the motorhome for the Brake Buddy to activate your toad's brakes. If you set the sensitivity high, then your car's brakes will activate with just a light tap of your RV's brakes. Low sensitivity will mean the system only activates when your motorhome brakes significantly.

Full Braking

You can also select the full-braking mode. When in this mode, the Brake Buddy will activate your toad's brakes at the maximum preset intensity, regardless of how intensely your RV is decelerating. The full-braking setting is ideal for when you're towing a heavy truck or SUV, or if you're towing your car down a steep incline. By setting the power to a higher level, you can ensure that the momentum of your toad won't cause it to push against your motorhome.

Easy Remote Operation

Brake Buddy Select Remote

It's important to monitor your toad's braking to make sure that everything's working the way it should. With the included remote, you can also control the Brake Buddy from the cab of your RV! It's just like having a brake controller in your motorhome.

With the remote, you can easily switch from proportional braking to full braking and vice versa with the push of a button. You can also change the Brake Buddy's sensitivity settings, which makes it easy to fine-tune the braking as you drive so that you can adjust based on feel. Finally, the remote will illuminate to alert you of any errors with the Brake Buddy system, including a breakaway event.

Breakaway System

The Brake Buddy also comes with a breakaway switch, an absolute must for safe flat towing. If there's ever an emergency situation where your toad becomes detached from the motorhome, the breakaway switch will immediately activate the brakes and bring your vehicle to a stop.

This switch mounts to the front of your toad and plugs directly into the unit. It includes a pin that connects to your RV's hitch receiver with a breakaway cable. If the toad and RV become disconnected, the cable will pull the pin out of the switch and trigger the braking system. A reserve air supply in the operating unit will then apply the brakes in the car.

39524 BrakeBuddy Select Three Portable Supplemental Braking System by Hopkins

Installation Details HM39524 Installation instructions

This Product Fits The Following Vehicles

California residents: click here

Customer Satisfaction Score:

Customer Reviews

Brake Buddy Select 3 Portable Flat Tow Brake System - Proportional - HM39524

Average Customer Rating:  4.5 out of 5 stars   (258 Customer Reviews)

This portable unit gets you smooth braking without a complex installation. Senses the RV braking and applies the brakes proportionally. Easy to swap between multiple towed cars: settings adjust for safe, even braking for any size car.


Once I got the right brake mount clamp and had the power cord from car to controller replaced, the unit has worked great, thank you.



Still great.


The proportional breaking never worked right and on our last trip the system kept cutting out until it quit working all together. I was in the southern US and had to drive back to Canada without the aid of the breaking system. i tried to check it out and fix it but was unable to get continuous power to the brake buddy.


Don't really like this system and decided to just tow without a braking system at all and all is good by doing so. This unit is awkward, expensive and a pain to use

Etrailer Expert

Katrina D.


I would definitely look into your states laws on pulling a trailer with or without a braking system. For instance, in Missouri, by law a supplemental braking system is not required except on trailers coupled by a 5th-wheel and kingpin. While in Idaho the law states "Trailers with an unloaded weight of 1,500 lbs. must have an independent braking system, and a breakaway system." Please double check your states laws before proceeding without a braking system.

Jeep Wrangler

I looked at several supplemental braking units and wanted one that was portable with nice features like wireless monitoring and parameter changes while flat towing my Jeep Wrangler. I reviewed the videos on the etrailer site for features and installation instructions, they’re well done and really helped with my buy decision and installation guidance. I decided on the Select 3 mainly because of the option for full or proportional braking, as I live in CA and take my RV through mountain passes often. The installation was straight forward with the help of the etrailer videos, very well done. The initial testing of the unit was a bit tricky, but it worked, after leveling the unit out. The first trip with the unit was from Southern CA to Paso Robles through the “Grapevine” pass and some other large hills, the unit worked well and gave me the extra braking I needed while flat towing my jeep behind my RV. During this trip, the unit was inconsistent in bleeding the brakes upon startup. I shared this information with etrailer in detail, and they sent me a replacement unit after trouble shooting. I want to thank etrailer for excellent support of a product which I entrust the safety of my family to while in use. The new unit has been wonderful on two other trips so far. I’m very happy with the performance and ease of use for the Select 3. It just takes a few minutes to position in the jeep, activate and get going down the road after the initial install was complete, which only took a few hours to run simple wiring. The unit is not very large or heavy, and easily fits in a normal storage compartment of the RV when we arrive at our destination. I look forward to many more trips with my family in our RV and the Select 3 giving us the supplement braking we need in our jeep on any road type.


have trouble with the brake paddle attachment locking onto the brake. setting the brake buddy adjustment take a while to adjust.


Plug keeps getting loose on unit. I drilled a hole in the case and installed a tie wrap attaching wire to case no more movement of plug works great otherwise


Overall good performance so far with the Brake Buddy. The only issue that we had was the cable connected to the unit would come loose during operation and send a “check Brake Buddy” error on our remote. We were able to easily remedy this by using a screwdriver to spread out the connection terminal to make it tighter as per customer service instructions.
Customer service is great & very helpful!

Jeep Liberty

I have had the brake buddy system 3 for a year and it's a great braking system, I have no problems and its works great with my jeep liberty.

2020 Jeep Wrangler

If you’re installing in a 2 door Jeep this brake buddy will install much easier if you 1. Remove floor mat 2. Set the driver seat all the way back towards the rear and 3. Lower the driver seat all the way down. By doing this the brake buddy will fit properly and allow for installing the cotter pin into the cleaver.


Nice unit, does what it is supposed to do and will noticeably slow my towed vehicle. It is a little cumbersome, but I set everything up in 8 or so minutes. Downside is that after one month long trip it would lose power after hitting a bump. Customer service was great and I eventually sent it back for repairs. They replaced a few things and has worked well until very recently. It appears that the plug will lose contact for a second over a bump and then the unit goes into a standby mode. The remote will let me know and I have to pull over and rebleed the unit. Some dielectric grease seems to have solved the problem


Hi Miranda, here are the pictures of the bracket and Brake Buddy installed in my Jeep. Works very well. I tried to move the seat forward a bit but when the Brake Buddy activated it pushed the seat adjuster and moved the seat all the way back. Thank you for the bracket.


Easy to get the car ready for towing. Just a few minutes. The permanent wiring with a battery tender makes towing worry free.

2012 Chevrolet Volt

Looking good so far. The only comment I can think of is a question as to why the wiring is different then standard 12 volt wiring. For example, ground in normal 12 volt is the black wire. Hot is the red. etc. The brake buddy doesn't follow that standard.

2014 Jeep Wrangler

This was super easy to install in my Jeep. The install video for the Wrangler was spot an very helpful. I installed a permanent brake system in another car before doing this one and I am so pleased with the install.

Now I am off to test it out.

Trevor B.


Ive been using this for a year now and have set it up a couple dozen times or more. This was so much easier than an installed brakes system. The only issue that weve had with it has to do with the power cable that connects to the 4 pin connector inside the vehicle. After some time the connector gets loose enough to fall out which requires is to pull over and reset the system. From Brake Buddy the fix is to look at the pins on the cable and where the tips of the pins almost look like you could a screwdriver, use a pocket knife or something thin enough to fit into the slots and gently spread them apart. I definitely recommend this device for a good, simple brake system.

Etrailer Expert

Mike L.


@TrevorB They gave you great advice, that's exactly what we recommend to folks that have the same problem with their # HM39524 Hopkins Brake Buddy.


Much Better than Air Braking. This system can be setup in one minute. I also have another vehicle that I use it with after purchasing an additional wiring kit. It’s easy and it works well. The wireless monitoring is flawless from the driver seat in my 38 foot Monaco Diplomat.


Had to remove weathertec floor mat and lamb wool cover from seat for proper fit. Company was very responsive in helping me with the fit to our CRV. Unit function very nice with smooth application of toad braking. Remote display is compact and clearly shows when unit is working. Quite happy with my Break Buddy.


This unit is large and hard to install each time in my Honda CRV

It works great when installed



Just OK - doesnt fit well in my Honda CRV - Awkward set up each time. Seems to work well


I’ve towed close to eight thousand miles in the past year. I had an incident when someone thought it amusing to pull my hitch pin while I pumped gas. The hitch dropped off about a half mile later and my break buddy saved me from any serious damage. Just got home today from a 3600 mile trip and no problem.



I had to replace the release pin on my tow hitch but with good tech support it was relatively easy. Had an incident with the brake buddy which caused the breaks on my toad to overheat. I don’t believe it was the device but rather the way I had installed it that caused the issue.since repairs. I have towed about 2500 miles without incident.

2019 GMC Acadia

So far so good! Haven't towed yet, but installation and test was successful. Install directions leave a little to be desired, all of the wires on the wiring diagram are black some have a color listed next to them some don't, it would have been a guessing game if it wasn't for the videos I found on etrailer. Upon initial test of the system, it went through its 5 actuations, indicated "normal" but kept the brake depressed, I double checked all the wiring, redid some iffy connectors, next test was the same, 5 actuations then an "error" light. Unplugged the system and waited 5 min, then performed test again. It tested well, showed "normal" but kept the brake depressed. I began to suspect the brake away switch. I repeated the pin with no luck, removed the whole assembly and the brake released. I found there was a factory splice point about 6 inches from the switch, I redid thoes connections and the system works as advertised!!
Thank you etrailer for the recommendation. Will update once I hit the road



Over the past year I have put about 10K miles on this unit, and it has been Flawless, up until this last trip. During A short 100-mile trip in January, I kept receiving the Check Brake Buddy Unit light. When checking the unit I found it would be powered off. After the 3rd time I disconnected the vehicle and drove it the rest of the trip. After some troubleshooting, I found the power cord at the Brake buddy unit to be intermittent. In order for the unit to work properly I have to apply a slight upward pressure on the power cord, once the pressure is released the unit loses power and turns off. I currently have to run some string through the thumb hole up to the steering wheel and tie it to maintain power, even then a large bump will turn the unit off. When the system works, its amazing, when it doesnt its very frustrating

Etrailer Expert

Heather A.


Hey James, this is actually a known design flaw with the power cord of Brake Buddies. It has since been fixed but Hopkins will help you out if you contact them. I will send you the deets.

2020 Jeep Wrangler

Just returned from our first camping trip with our Wrangler in tow. The Brake Buddy worked flawlessly and gave me the piece of mind I needed to safely tow a vehicle behind our RV! Takes some time to get it installed and adjusted the first time and then is an absolute breeze to install subsequent times. A great product!


BrakeBuddy is a great product. I had verified this newer style included a 12 volt plug. It does, but there is no where to plug it in according to their manufacturer, Hopkins. I will need to rewire two tow vehicles before I can verify that this item works. The box was delivered and dropped off on my driveway without a signature for a $1300 item!!! Also, the box was not even taped shut. I have verified that all the parts are present.

Etrailer Expert

Thomas M.


Instead of connecting to a 12V accessory outlet, the Brake Buddy 3 draws power directly from your towed cars battery. To do this, the included wiring harness connects to your cars battery. Install the harness by routing the wire end through your cars firewall and into your engine compartment. Connect the harness to your battery with the included battery wire and ring terminal. Mount the connector thats on the opposite end of the harness in a convenient, out-of-the-way location beneath your cars dash.



Having rewired two vehicles to use the new BrakeBuddy my husband and I had an RV trip with friends to four wheel around the Anza Borrego State Park in California. The BrakeBuddy performed flawlessly on the trip down there in our 4 wheel drive truck. Setting up to come back it would not power up. We discovered that the inline fuse was blown, replaced it and home we went. The RV needed some maintenance so we hooked up our hybrid car, setup with the new BrakeBuddy, and delivered the RV to the shop. When we went to pick up the RV, the BrakeBuddy would not power up hummm. Again, we found a blown in line fuse, replaced it and headed home. I contacted Hopkins Manufacturing about this. They thought the problem might be in the unit and requested that I send it to them. They kindly offered a prepaid mailing label. They found a short in the wiring and the unit was back to me within a week. This is my second BrakeBuddy and I was quite happy with Hopkins service on our first unit which we used for over 15 years. We only purchased a newer model because of the hybrid vehicle.

2017 Jeep Wrangler Unlimited

Peace of mind! That's what this gives me. We have towed several times with it now and it's an ease to set up. The first time took a little longer, as to be expected, but now that everything is set where we need it is so easy to drop in and hook up.

Dodge Charger

I had to set the height up to miss the seat release and the driveshaft release. I do not have it braking the toad yet so the review might be premature. No one explained how this works. It does not connect up the the brake light but rather uses slow down sensing. Also, matching the wire colors would have been nicer (breakaway switch has black and red wires but they are connected to the brown and red on the brake buddy loom. The black wire was power and was to be connected to the red wire which was connected to the battery. The fused wire for power had a ring connector just 3 inches from the fuse so you could not mount the power fuse as configured. I wanted to mount the two fuses and the battery charger on the fender well so had to do some cutting.

2010 Honda CR-V

I have owned an older Brake Buddy Classic model for about 18 years. I wanted to update to the Select 3 and found the eTrailer price to be the best deal. Very pleased with the install of the select 3 and its improved functionality. Fits tight in my 2010 Honda CRV but workable. Looking forward to our first trip using the new Select 3.


I've used this in a 2022 Chevy Colorado ZR2 - towed behind a 2016 Thor Axis. The unit works as expected, but after 5000 miles of towing (Over 2 months) one of the connectors seemed to lose it's tight fit. When hitting a bump in the road, they system would disengage due to the connector wiggling loose ever so slightly. I'd have to pull over and push it back in. This continued to happen until I utilized duct tape - the master fix-it item.)

Show More Reviews

See what our Experts say about this Brake Buddy Tow Bar Braking Systems

Do you have a question about this Tow Bar Braking System?

Info for this part was:

Employee Mike L
Expert Research:
Mike L
Employee Jameson C
Expert Research:
Jameson C
Employee Lindsey S
Edited by:
Lindsey S
Employee Jeff D
Video Edited:
Jeff D
Employee Joshua S
Video Edited:
Joshua S
Employee Jacob T
Video Edited:
Jacob T
Employee Dustin K
Video Edited:
Dustin K
Employee Chris R
Video Edited:
Chris R
Employee Jonathan Y
Video Edited:
Jonathan Y
Employee Leah S
Updated by:
Leah S
Employee Mike S
Updated by:
Mike S
Employee Isabelle B
Updated by:
Isabelle B
Employee Noah M
Updated by:
Noah M
Employee Amanda K
Updated by:
Amanda K
Employee Alexander C
Written by:
Alexander C
Employee Shane H
Test Fit:
Shane H
Employee Conner L
Test Fit:
Conner L
Employee Ryan G
Test Fit:
Ryan G
Employee Bradley B
Test Fit:
Bradley B
Employee John A
Test Fit:
John A
Employee Jacob H
Video by:
Jacob H

At we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time. Let us know if anything is missing or if you have any questions.