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Demco SBS Stay-IN-Play DUO Supplemental Braking System - Proportional

Demco SBS Stay-IN-Play DUO Supplemental Braking System - Proportional

Item # SM99251
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Tow Bar Braking Systems

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Demco SBS Stay-IN-Play DUO Supplemental Braking System - Proportional Power Assist Brake Compatible SM99251
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Product Expert Mike S

Is this right for you? Product Expert Mike S says:

Yes, if you:

  • Don’t have time to waste setting up a portable system before every trip
  • Don’t have extra storage space in your RV to store a portable box system
  • Want a permanent system that’s easy to install

No, if you:

  • Upgrade your towed car every few years
Get automatic, proportional braking with a system that never has to be removed, replaced, or reset. The DUO activates when your RV's brake lights go on and an inertia sensor in the towed car detects deceleration. No false braking. Lowest Prices for the best tow bar braking systems from Demco. Demco SBS Stay-IN-Play DUO Supplemental Braking System - Proportional part number SM99251 can be ordered online at etrailer.com or call 800-298-1624 for expert service.
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  • Reviews (256)
  • Q & A (0)
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  • Why etrailer?

Demco Tow Bar Braking Systems - SM99251

  • Brake Systems
  • Proportional System
  • Hydraulic Brakes
  • Fixed System
  • Demco
  • One Time Set-Up
  • Power Assist Brake Compatible

Get automatic, proportional braking with a system that never has to be removed, replaced, or reset. The DUO activates when your RV's brake lights go on and an inertia sensor in the towed car detects deceleration. No false braking.


  • Supplemental braking system applies towed vehicle's brakes in proportion to braking action of RV
    • Towed car's brakes are activated at the same time and with the same intensity as those in your motor home
  • Inertia sensor detects deceleration and signals system to activate brake pedal with proportionate amount of pressure
  • No false braking
    • Coach brake light must be on for system to activate towed car's brakes
  • Sensitivity control on the inertia sensor lets you regulate how aggressively the towed car's brakes activate
  • One-time setup - no need to remove or to activate each time you tow
    • Operating unit and actuating cylinder stay hidden so everything is out of your way when driving
    • Inertia sensor mounts in the cab of the vehicle
    • System automatically functions when towed vehicle is hitched to RV
  • LED coach notification system illuminates when the towed vehicle's brakes are applied
    • Connects to towed car's brake light switch to ensure proper reading
  • Vacuum pump restores towed car's vacuum after each braking event
    • Less force is needed to move the brake pedal in the car, resulting in more natural braking and less risk of damage
    • Compatible with vehicles that have continuous-power-assist brakes
  • Breakaway included
  • Necessary installation components and instructions included
  • Made in the USA


  • Operating unit dimensions: 8" long x 5" wide x 2-1/4" tall
  • 5-Year warranty

Note: Works with Re-Install Kit SM6270 to use in another tow vehicle.

A supplemental braking system is a must when towing a car or truck behind your RV. Without it, the weight of the towed car can create a safety hazard, strain your RV's brakes, or affect your RV's warranty. Most states require a supplemental braking system.

Automatic, Proportional Braking

There are many supplemental braking systems available to RV owners who choose to tow a car. Stay-IN-Play DUO combines the best features into a single system that is both automatic and fully proportional. This system relies not only on your towed car's momentum to activate, but also on your RV's brake light signal. As a result, the DUO will automatically activate any time you engage your RV's brakes, so long as there is enough deceleration for the system to detect. And when it does activate, your towed car's brakes will engage with an intensity that matches the slowing or stopping action of your RV.

An inertia-sensing mercury switch inside the DUO's controller is what makes this system proportional. This switch reads and interprets changes in forward momentum that occur when your towing setup decelerates. As your RV and car slow down, this switch sends a signal to activate your towed vehicle's brake pedal with an intensity that matches the deceleration of your RV. The result is even braking across your towing setup. Whether you lightly tap the brakes in your RV or apply them hard in a panic situation, your towed car's brakes will be applied proportionately.

Dual Activation Signals

G Force Controller

The G-Force controller is responsible for sending the signal that activates the brakes in your towed car. When the coach brake lights come on, the tow bar wiring sends a signal to this controller. This signal powers the internal, inertia-sensing mercury switch, enabling it to detect deceleration. If a change in forward momentum is detected, the G-Force controller initiates the braking process by sending an activation signal to the system's operating unit.

If the mercury switch is powered but there is no change in momentum, the system will not activate the towed car's brakes. Likewise, if a decrease in forward momentum occurs but there is no brake light signal from the RV, the inertia sensor will not be able to register the deceleration, and the system will not activate the towed car's brakes.

Because the DUO will not work without your RV brakes being applied, there is no false braking. When you downshift in your RV without applying the brakes, the DUO will not mistakenly depress your towed car's brake pedal because that first activation signal is not there. And because there is no time delay, this proportional system delivers instant braking in an emergency.

Note: The G-Force controller mounts in the towed car and must be pointed it in the direction of travel - with the toggle switch facing the rear of your vehicle - for the internal sensor to function properly.

Sensitivity Adjustment

You can adjust the sensitivity of the inertia-sensing mercury switch with a knob on the front of the G-Force controller. Adjusting the sensitivity lets you decide how intense the change in momentum must be for the sensor to respond. Adjust it to fit your personal preference so that you can get a customized braking experience. Set the sensitivity low and the DUO will only respond when you forcibly step on your RV's brake pedal. Set the sensitivity high and it will respond when you merely tap your RV's brakes.

To fine-tune the sensitivity, first move the knob all the way to its most sensitive setting. From there, you can apply the coach brakes and gradually move the knob until you get the setting right where you want it. You only need to set the sensitivity upon initial setup.

Permanent Installation with Concealed Components

Operating Unit

The operating unit receives the signal from the G-Force controller to activate. It then delivers air through a hose to the actuating cylinder, which depresses the towed car's brake pedal with a pressure that ensures your car will brake in proportion to the deceleration of your RV.

DUO Under Hood

Once you install the Stay-IN-Play DUO's operating unit under the hood of your towed vehicle, it stays concealed. Not only will it be installed and ready for the next time you want to tow your car, but it will also be out of the way so that you won't notice it when you drive your car normally. In addition, there is no need to constantly set up or remove this system. As a result, you don't need to worry about where to store the components when you're not towing.

Actuating Cylinder

Small Cylinder

The actuating cylinder depresses your towed car's brake pedal upon receiving air from the operating unit. This small cylinder stays mounted on the arm of your towed car's brake pedal at all times and will not interfere with braking while driving.

Actuator on Pedal

Mount this cylinder so that it is perpendicular to the firewall when you depress the brake pedal. A clamp anchors the actuator to the firewall.

To connect the actuating cylinder to the operating unit, you will need to run the included air hose through your towed car's firewall. You can usually create the necessary, small opening without drilling. In most instances, you can cut a slit in the hood release cable grommet. Simply cut the end of the air line at an angle to poke it through the slit.

Vacuum Pressure Creates Smooth Braking

Normally, when you activate the brakes in your vehicle, a vacuum multiplies the pressure you apply to your brake pedal, creating the force necessary to stop the full weight of the moving car. On most cars and trucks, this vacuum-assist function does not work when the engine is off. As a result, many supplemental braking systems on the market have to use an excessive amount of pressure to effectively depress the towed car's brake pedal.

The Stay-IN-Play DUO's operating unit ties into your car's vacuum line and uses a built-in vacuum pump to activate the vacuum-assist function of your car's brakes when it's being towed. As a result, the actuating cylinder of the Stay-IN-Play DUO does not need to apply extreme force to the brake pedal to achieve proper braking. The Stay-IN-Play DUO will replenish your towed car's vacuum after each braking event so that you will get smooth, even braking every time.

Built-In Safety Features

Most supplemental braking systems have methods of letting you know you when the system itself is activated, regardless of whether the towed car's brake pedal is depressed. Such setups leave opportunities for false notification. The Stay-IN-Play DUO's system is different. This system's LED monitor connects to your towed car's brake light switch. When your car's brake light goes on or off, so does the notification light. So you can tell whether your car's brake pedal is depressed.

You can install the monitor light on your RV's dash, or you can save time by attaching the monitor light to the back of the rearview mirror of the towed vehicle. This way you can see the light from your RV's backup camera or rearview mirror. The system includes the necessary parts for either installation method.

The breakaway system ensures that your car will come safely to a stop if it accidentally detaches from the RV while you are towing. A switch mounts to the front of the towed vehicle. This switch - which is wired into the operating unit - includes a pin that connects to your RV's hitch receiver with a breakaway cable. If the car separates, the cable pulls the pin from the switch, causing a signal to be sent to the operating unit.

9599006 Demco SBS - (Formerly SMI) Stay-IN-Play DUO Supplemental Proportional Braking System

Replaces Demco SBS SM99251

Installation Details SM99251 Installation instructions

This Product Fits The Following Vehicles

Customer Reviews

Demco SBS Stay-IN-Play DUO Supplemental Braking System - Proportional - SM99251

Average Customer Rating:  4.8 out of 5 stars   (256 Customer Reviews)

Get automatic, proportional braking with a system that never has to be removed, replaced, or reset. The DUO activates when your RV's brake lights go on and an inertia sensor in the towed car detects deceleration. No false braking.

- SM99251

Haven't actually had the chance to tow behind yet so this is just for the install. It took me quite a long time to install but, that's not the products fault. Everything you need to do the job is included. I only give it 4 stars because the system uses the towed vehicles battery to activate the vacuum/compressor pump, so it would be possible to run the battery down as there is no charge circuit from the towing vehicle. I did choose to add one though. Other than that I'm sure it'll work fine. It was installed on a 1983 Vanagon.

Im not in the car when it works, but the indicator light comes on so I assume they work. Honestly, my motorhome is so big I cant tell if there working or not, mostly I stalled to be legal and safe. I like it.
David - 10/21/2021

- SM99251

I personally installed this on my 2020 Jeep Wrangler and have towed it using this braking system over 4K miles and have had zero issues. Would definitely recommend! The installation instructions were well written and included an easy to read wiring diagram making is easy to install and the very knowledgeable etrailer support was a bonus too!

- SM99251

We wired this into a 2017 Ford CMax and it has worked ideal braking system, just switch it on when connected to our motor home and we are ready to go. We mounted the unit behind the drivers seat in a floor compartment to keep it dry and it has worked perfect. It was a little tricky to get the toad indicator light to work, required a separate switch kit to be purchased but once that was wired in we can see the brake pedal indicator lighting up and know that our unit is working as it should.

- SM99251
Saturn Relay

This braking system has worked very well and is effortless to enable and disable. One thing I would encourage users to do is to determine all accessories that will be needed for the install (I.e. brake light relay, indicator light on coach dash, wiring kit, etc). Pulling all of the needed wires thru the firewall at one time is much easier. Don’t ask how I know this LOL I would recommend this product

- SM99251

I ordered a Falcon II tow bar, Base plate for a GMC Canyon, Demco Stay-n-play braking system and safety cables. worked exactly as it should, directions were easy to follow. All hardware was included. This system allowed us to tow our Canyon 10K miles around the country. super easy to use and I was able to connect and disconnect in less than 5 min. I liked the system enough that I bought the same setup for our new vehicle.

- SM99251

Installation does take alot of additional kits due requirement of Jeep to disconnect battery. Very pleased with system. Wiring print was a real plus and online video

- SM99251
2019 GMC Terrain

This has been installed in our 2017 GMC Terrain for a year, we have navigated numerous highways and country roads, even did the I-40 stretch by Ashville, with super steep grades, this has performed flawlessly, hook up requires a flip of a switch and away we go. Never do we feel any tug or push, the Terrain brakes nicely and nothing to install and remove each time, disconnect tow bar, flip a switch and you are driving towing behind a 2019 Tiffin 36UA

- SM99251

I used the video from etrailer and it was very helpful, I added a terminal strip near the vehicle battery to help me keep track of everything and I moved the brake indicator LED to the motorhome dash instead of the tow vehicle, overall the system works great and I have towed for over 7000 miles since the install

- SM99251

This setup saved my 2020 Civic. Had an uncommanded tow vehicle disconnect. Yes, it was my fault. However, the Demco system activated as designed and I was able to pull over and reconnect with no damage. Without this system, the tow car would have been all over the back of the RV. Very impressed with the performance of this system. Installing it was made easier as I had to remove the Civic bumper cover to install the tow bar base plate. I was able to install the operating unit just below the left headlight behind the bumper cover. All of the wire and hose routing was easy. I could go on about how well this unit saves my RV brakes on long descents, but it’s already paid for itself.

- SM99251
2016 Ford Edge

Thanks to installation videos provided by etrailer, I felt confident that I could do the install myself. I had never pulled off moldings and panels in a car before, but with your videos as guidance , it was a breeze. This system was going into a 2016 Ford Edge 3.5L AWD and your (and SMI's) instructions call for installation of 2 check valves. After calling SMI to clarify the install points, it got even easier, as only one valve is required, and is ridiculously simple to install it. No cutting of original car hoses required (see photo). After everything was installed, the whole setup just simply worked, no troubleshooting required. That was fun and it is totally doable, even for the average guy like myself.

The rear-view camera display in my RV is not good enough to show the operation of the brake notification LED which is applied to the rear-view mirror in the towed car. I installed a small light in the RV dash and ran wiring all the way back to the toad, with a disconnect plug at the hitch, of course. Now it is easy to see when the car brakes come on. Else, the system works great.
Herbert M - 07/13/2018

- SM99251

This is a great breaking system. It took me about 3 hours working off and on to install. just plug it in and turn it on and you are ready to go

LOVE it. very easy hook up.Works great
Namron - 06/14/2021

- SM99251

Overall, this is a great system. Biggest disappointment is the LED brake indicator that comes with the kit, and is mounted to the backside of the rearview mirror, is not bright enough to be seen through the RV rear camera. This necessitated in us having to purchase the optional and expensive brake indicator that goe inside teh RV cab.

- SM99251

Very happy with the way this turned out. Video was very helpful. Only thing I didn't really care for was the red LED that was to be mounted on mirror. Purchased a red LED light at parts store and mounted in grill, see picture, using alternate connection. Much easier to connect and much easier to see in RV camera.

- SM99251

I have not actually tried it on the road, but it activates as advertised. Thus only 4 stars. It replaced an old Cumbersome Brake Buddy. Working under the dash was the most difficult part. The LED notification lite does not work the wire is very flimsy. Will update when I get on the road.

- SM99251
2003 Subaru Outback Wagon

I chose to go with this unit because I didn't like the idea of the other types that mash the brake pedal without any vacuum assist & the fact that you have to remove, then reinstall them each time you want to use the car. This ended up TOUGH install. Not because of the unit, but rather the lack of ANY room under the hood on my 2003 Subaru Outback Wagon to mount the operating unit. The only place I could find that would be out of the way was under the driver's seat of all places! Luckily there was JUST enough hose with the unit to reach all the way to the brake booster. I had to cut the carpeting so the seat would clear the operating unit during movement without any chance of contact. There was no hole in the firewall large enough to accommodate the hose so I had to drill a hole for that although I was able to route the wiring through a small rubber grommet. Routing the hose to the firewall was a real challenge! I ended up running it through the heater duct under the driver's floor mat to the left side kick panel, then up over the pedals keeping clear of any moving parts. WHEW!! The brake pedal actuator went on without much fuss, although with my large feet I have noticed I'll catch the actuator with my toe on occasion. I may mark the location it's in now & merely raise it up a tab in between trips. The wiring was pretty much straight forward, there was plenty of included wire & I had JUST enough room tho mount the G-Force Controller on the left kick panel covering without interfering with my feet. The breakaway switch I fastened to the body in front & below the radiator. I read where everyone was saying you need to have a battery cut-off device to keep the braking system from draining the battery over time, but I had power from the RV keeping the battery fresh so I didn't worry about that & saved myself the $180 for the cost of an automatic battery disconnect. After installation, I sat in the car while we towed it around the neighborhood to see how it worked & made the necessary adjustments to the G-Force Controller. Now THAT was weird! What with the car steering itself & braking too. We just got back from a 4,000+ mile trip & everything worked fine. On occasion I forgot to flip the switch to turn the system off, but it didn't seem to make much of a difference. All in all a great system!

- SM99251
2018 Jeep Wrangler

After doing much research and reading many reviews and watching a lot of your instructional videos I chose the Stay-in-Play Duo. It came complete with instructions and extra parts for any application. I like the fact that after everything is installed it is just a matter of flipping a switch and checking it out and drive off. I mounted it in a 2018 Jeep wrangler, not very much room for the operating unit, but I I went off of one of your videos on a 2017 Jeep Wrangler Unlimited and mounted it underneath above the cross frame below and behind the radiator but still protected from the elements. Not a lot of room under the dash either, but everything is in and looks great and ready for the 1st trip.

- SM99251
Jeep Cherokee

Had it installed by my RV Service guy, and it’s worked great for us in towing our Jeep Cherokee with the Roadmaster Falcon 2 towing system!

- SM99251
2012 Dodge Charger

I installed this in a 2012 mini Cooper S. With the turbo charger there is no room in the engine compartment for the system unit, so I mounted it under the passenger seat. I had to remove the seat, cut out the carpet, mount the unit, and then buy longer seat attachment bolts. I used half inch thick spacers between the seat track in the floorboard. Made a long run for the vacuum hose to get up to the engine compartment through the firewall. By removing the cowling on the driver side, it exposes a huge Gromit where the main wiring harness passes through the firewall. It actually had two nipples ready to be cut off to run the vacuum hose and the wires through — so that part was pretty easy. I haven’t towed it behind the motorhome yet, but it passed all the start up tests the first time!

- SM99251
Jeep Grand Cherokee

Ok. This takes a bit of time to install. Plan for a full day. Not that it is all that hard but I wanted it to look nice and finding a way through the firewall on my Jeep Grand Cherokee was not easy. But I do love how it operates. Found the sweet spot for the Toad to help just a little when braking.

- SM99251
2018 Ford F-150

I installed this braking system on my 2018 F-150 Lariat over a period of several weekends. I took my time and have the satisfaction of knowing exactly how the system works. The instructions suggested mounting the main control box on the lower frame under the engine but I chose to place it on top of the main fuse box under the hood. It isn't going anywhere and is easily moved to check fuses if needed. Take a few hours and pull your toad around while fine tuning the braking level. I ended up pulling over to re-adjust the cable once and the sensitivity knob several times to make it perfect. Very happy to have brakes on my F-150 while towing behind my coach.

- SM99251
2012 Chevrolet Spark

Installed this on our Chevy Spark. It was a fairly simple install. It was a bit more time consuming than I had expected. It has been about a year now and 12,000 miles since the install and it is working well.

- SM99251

It wasn't easy to get everything installed in a way that looked neat and professional but in the end the ease with which you can hook up the car and start towing makes it worth it. I bought a replacement factory vacuum pump line so that I didn't have to worry about ruining the original one and as a result the installation looks that much better. Literally all I have to do is flip a switch once the car is connected and I'm ready to go. Given a second opportunity to do the installation I would mount the LED light strip vertically on the backside of the rear view mirror to make it a bit more visible but other than that, I'm happy with how it turned out and the system works great.

- SM99251
2015 Jeep Wrangler

SMI Stay in Play Duo installation in 2015 Jeep Wrangler Unlimited – Packaging was great with everything needed included plus extra items for various installation methods of you’re choosing. Upon initial investigation and survey, everything except the CD Information pack was accounted for. No big deal, as I had previously watched 2 different Youtube installations found on the internet. In fact, the internet videos were what I used as my step by step installation process, and the written instructions were only used for concerns where the video may not have been as clear as I had hoped for. Understanding that everyone has their own style and methods for doing this project, I purposely was not in a hurry to rush through it. All in all, I took @ 8 hours to install the Adapter 4 to 6 pole #30637, the EZMount Tow lights Kit, and the Stay in Play Duo Braking System. I choose the EZMount because I didn’t want to mess around with the OEM taillights and wiring. Magnetic lights don’t work so well on composite tops and I didn’t want to stick them to the sides of te Jeep, so I modified the EZ mount to wrap around the thickness of the rear glass hatch on both sides. I added a 2”x 4” pc of Velcro on the inside of the glass hatch and the mating surface of the plastic light housing - to hold the lamps in place until the rear gate was closed. I ran the wire harness on the inside under the trim all the way up to the front and through the grommet in the firewall. The flat 4 wire was routed and secured up to the Adapter 4 pole to 6 pole that I had fastened to the Blue Ox base plate. The actual installation of the SMI unit and assorted parts went rather smoothly. Most difficult issue was the lack of working space in front of the driver’s seat area. Installing the screw that holds the G force controller on the front (the side towards the front of the car) was difficult as it was almost a blind installation due to lack of room. The nut and fender washer used through the fire wall for attaching the air cylinder cable bracket was a challenge to reach - tight fit with not much room for one's hand and arm. Other than that, no big surprises – just a lot of tedious steps to do when you want to be sure that it is being installed properly – take your time and don’t be in a hurry. Once everything was installed – it all worked when I checked the system out. The only thing that may seem a bit odd is that when setting the G force initially, the compressor will shut off while adjusting per instructions. To do this initial adjustment, the wife stepped on the brake in the Motorhome, with the switch “On”. The compressor starts, and the brake is pushed down by the Air Cylinder, at which time I slowly adjusted the G force until the compressor shuts off. I secured the adjusting bolt and I told the wife to take her foot off the brake and then re-apply them. The compressor did not start again and the air cylinder did not apply the brakes in the Jeep. After setting the G force per instructions, the unit didn't turn on when the brakes in the Motorhome were applied - but since we were not moving - all I can assume is that the brake system will function while slowing down once the accelerometer setting (the sensitivity setting on the G force box) has been met. I assume that the sensitivity setting method includes a way to ensure the Jeep brakes are not engaged too frequently and only until needed. This is the only step that is a tad bit confusing without an explanation as to what to expect once the G force sensitivity is set. Lastly, I checked the brake away switch and it turned the compressor on and applied the brakes as expected. Overall - the installation went rather smoothly. Can't wait to see how the product works once we hit the road. I'll check back and provide an update later.

Still working as expected, trouble free and no problems since the install.
Mike A - 10/23/2018

- SM99251

Ordered online and was shipped very quickly. Box arrived in good shape. Watched a number install videos by etrailer and got the job done. System seems to be working but have not had a chance to tow behind motor home yet. Thanks!

- SM99251

LOVE this braking system. Install was straight forward. I had installed an Invisibrake on a different TOAD and this system is much easier when it comes to hooking the device to the brake pedal. Highly recommended!

Show More Reviews

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    You are on the right track for the parts you'll need to flat tow your 2020 Jeep Gladiator but you do need a lighting solution so that your Gladiator taillights activate like they need to when towing. Since you already have some of the wiring from the Nighthawk you'd just want the part # RM-154 and you'd be set! I attached an install video for this kit on a 2020 Gladiator for you to check out as well.
    view full answer...
  • Trailer Brake Controller That Can Be Used with Towed Vehicle Braking System
    A standard trailer brake controller that mounts in the tow vehicle to power trailer brakes cannot interface with a separate supplementary vehicle braking system but there is one product we offer, the Brake Buddy Stealth Supplemental Braking System # HM39530, that combines both a trailer brake controller and a vehicle braking system in one setup. The linked video will give you a recap of the system's components and also its capabilities. This item is a confirmed fit on your 2016 Wrangler.
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  • Blue Ox Base Plate Kit and Tow Bar Lighting for 2015 Ford C-Max
    Basically you just need the correct base plate kit for your 2015 Ford C-Max from Blue OX part # BX2639 and then a lighting solution and you'd be set. For lighting you can use the diode kit, # RM-15267, and not have to worry about cutting into the taillight housing. This will splice into your taillight wiring to allow your tow vehicle to control the taillight assemblies of the towed vehicle. This comes with a round 6-way connector that you will install on the front of your towed vehicle...
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  • Parts Needed to Flat Tow 2014 Ford Explorer
    There are several components to safely flat tow your 2014 Ford Explorer, a base plate, a tow bar, safety cables, a wiring/lighting solution, a battery charge line and a supplementary braking system. I linked an article that goes over all of these in detail. The Blue Ox Base Plate Kit with removable arms # BX2632 is confirmed to fit if you have the 3.5L v6 or the 2.0L ecoboost and the one I recommend. I think it has a clean look on the front of the Explorer when your not towing. The arms...
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  • Electrical Components Required For Flat Towing A 2016 GMC Canyon
    GM requires you to disconnect the battery to prevent damage to any of the electrical components while flat towing your 2016 GMC Canyon. Failure to do so would place all liability for damaged components solely on you. I recommend installing the Roadmaster Automatic Battery Disconnect with Switch for Towed Vehicle w/ Supplemental Braking System # RM-766 to make disconnecting the battery as easy as flipping a switch. Since you'll be travelling quite a distance I do recommend installing...
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  • Does Flat Towing 2020 Jeep Wrangler Require Using Brake Light Relay
    To determine if you need the Roadmaster Brake Lite Relay part # RM-88400 you'll need to first put your 2020 Jeep Wrangler in ignition position that it needs to be in when towing (check owners manual) and then check to see if the brake lights of the vehicle come on when you hit the brake pedal. If not you do not need the relay but if so you will. I attached an install video for it for you to check out as well.
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  • SMI DUO or Invisibrake Recommendation for 2005 Jeep Wrangler
    The SMI DUO # SM99251 is the best option for supplemental braking for a vehicle that permanently installs. Our installers prefer this kit to all of the other ones as it's got an easier install and performs really well when flat towing. For your 2005 Jeep Wrangler this would be the best option. I attached an install video for this on a similar Wrangler as yours for you to check out too.
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  • Mounting Location for Stay and Play DUO Operating Unit
    When I installed the Stay-IN-Play DUO # SM99251 in a 2018 Jeep Grand Cherokee I mounted the operating unit in the front of the engine bay on the core support. You can mount the operating unit anywhere that the wires and hoses can reach; it's just recommended that it mounts in the engine bay away from direct water exposure and extreme heat sources. After installing many flat tow set ups on different vehicles, the biggest piece of advice I can give you is to plan out your install. Take...
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  • Will Stay-IN-Play Duo Supplemental Braking System Work on RV With Air Brakes
    Technically the SMI Stay-IN-Play DUO Supplemental Braking System # SM99251 you currently have is still going to "work" with your 2018 Jeep JL Wrangler Unlimited and new RV with air brakes, but the issue is that you are going to get false braking because it uses both the RV's brake lights and deceleration to apply the brakes. This is going to make your drive less comfortable and more importantly, wear out your Jeep's brakes quicker than need be. It could even go as far to drag the Jeep as...
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  • Are Additional Diodes Needed for Demco SBS Stay-IN-Play DUO Supplemental Braking System
    You will not need additional diodes when installing the Demco SBS Stay-IN-Play DUO Supplemental Braking System # SM99251. The 10 amp diode that come with the kit are only needed if your tow wiring harness is not diode-protected. Since yours is not, you will install the diodes in-line with the green and yellow wire from the G-Force controller to the green and yellow tow bar wires. I have added an install video for you to check out as well of the Demco SBS Stay-IN-Play DUO Supplemental...
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  • How to Install Stay-IN-Play DUO in New Jeep
    I spoke with my contact at SMI and he advised not to install the Stay-IN-Play DUO # SM99251, which you referenced, under the seat but to install it on the toe kick per the installation instructions. He said it will not work if placed under the seat because the unit needs to be mounted level as it is working off inertia. The operating unit measures 8" long x 6-1/4" x 2-1/2" tall. (See photo.) He said the units have been fitted in all new Jeep models and that they will fit, you will...
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  • Recommended 2016 Chevrolet Sonic LTZ Auto Flat Tow Equipment
    For a permanent install braking system for your 2016 Chevy Sonic the SMI DUO Stay and Play part # SM99251 is the best option. But if you wanted something that installs easier but requires removal and re-installation every time it's used the Blue Ox Patriot part # BRK2019 is the best option for that. You'll need the outlet kit part # RM-9332 to go along with this to power it. For a base plate kit the part # 523173-4 is a confirmed fit and would work well. The most popular compatible...
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  • Installing SMI Stay-in-Play DUO Braking System SM99251 in 2018 Jeep Wrangler JL
    My contact at SMI advised that the Stay-in-Play DUO Supplemental Braking System # SM99251 that you currently have installed in your 2006 Jeep TJ can be installed in the 2018 Jeep JL Wrangler by cutting the JL's 8mm hard plastic line and installing the SMI 3/8-inch vacuum hose. SMI recommends also using a worm clamp for a secure connection.
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  • Supplemental Breaking System and Lighting Kit to Flat Tow 2013 Honda Fit
    For lighting you can use the diode kit, # RM-15267, and not have to worry about cutting into the taillight housing. This will splice into your taillight wiring to allow your tow vehicle to control the taillight assemblies of the towed vehicle. This comes with a round 6-way connector that you will install on the front of your towed vehicle and enough coiled wire to go from there to the RV. The SMI DUO part # SM99251 you are thinking about is the way to go. This is our installers favorite...
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  • Parts Needed to Flat Tow 2005-2007 Jeep Liberty Behind RV
    In order to flat tow your Jeep Liberty behind an RV/motorhome, you need a base plate kit, a tow bar, safety cables, a lighting solution, a supplemental braking system, and likely a high-low adapter. Starting with the base plate kit, I recommend the Roadmaster EZ5 Base Plate Kit # RM-521423-5. These base plates are custom fit for your Jeep and feature a hidden bracket design for a clean look when you aren't towing. Its black powder coat finish is durable and will work do a nice job of...
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  • Recommended Supplemental Braking System to Flat Tow a 1999 Jeep TJ
    We do have a few supplemental braking systems that will fit your 1999 Jeep TJ. I recommend the SMI Stay-IN-Play DUO Supplemental Braking System - Proportional # SM99251 which becomes plug and play after the initial installation. It does require the relay # RM-88400 to prevent the towed vehicle's brake signal from overriding the turn signal from the RV when applying the brakes during a turn. If you want an easy installation that requires just a short install time for each use, I recommend...
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  • Recommended Supplemental Braking System to Flat Tow a 2019 Fiat 500
    The supplemental braking system I recommend for a 2019 Fiat 500 is the Stay-IN-Play DUO Supplemental Braking System part # SM99251 if the coach has hydraulic brakes or the Air Force One Supplemental Braking System part # SM99243 if the coach has air brakes. The Stay-IN-Play and Air Force One are two of my favorites because they are generally easier to install than most other permanent options. If you will not be installing the system yourself then the easier install means you could potentially...
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  • Can Roadmaster Rock Guard Be Used When Flat Towing 2018 Buick Envision
    Yes, you can use a Roadmaster Guardian Rock Guard # RM-4000 when flat towing your 2018 Buick Envision. You'll need to use a Roadmaster flat towing setup that has the crossbar so let's get you set up with that as well. Starting with the base plates I recommend the Roadmaster EZ4 Base Plate Kit # RM-523188-4. This base plate kit is custom fit for your vehicle and features a hidden bracket design for a nice clean look when you aren't towing. For a compatible tow bar that will work...
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  • Is a Tow Vehicle Battery Charge Line Needed for Supplemental Braking System Like Stay-In-Play Duo?
    When using any supplemental braking system on any vehicle, I recommend adding a charge line to the vehicle being towed. The Roadmaster Battery Charge Line Kit for Towed Vehicles # RM-156-25 is easy to install and simply gives that additional peace of mind that your TOAD will start without any issue once you get to your destination even when it has been a lengthy trip. This kit simply uses your wiring connection from your motorhome to maintain your vehicle battery so that it is never...
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