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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
Our Price: $1,175.00
You Save: $410.79
Tow Bar Braking Systems

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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. Great 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 or call 1-800-940-8924 for expert service.
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Demco Tow Bar Braking Systems - SM99251

  • Brake Systems
  • Hydraulic Brakes
  • Proportional System
  • Demco
  • Fixed System
  • 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 Jeep Wrangler Unlimited
    • 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 Jeep Wrangler Unlimited.

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 Jeep Wrangler Unlimited'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 Jeep Wrangler Unlimited - 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 Jeep Wrangler Unlimited, 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 Satisfaction Score:

Customer Reviews

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

Average Customer Rating:  4.8 out of 5 stars   (503 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.

2017 Chevrolet Spark

I mounted this in a 2014 Chevy Spark. Finding a spot for the main control unit was interesting, but I found a video for a 2017 Spark that I could use. I did have to drill an extra hole in the mounting flange and car. I haven't taken it on a trip as of this time, but a tow around the block indicated it was working. One note, watch about placing the LED indicator behind the tinted part of the toad window. It makes it harder to see from the camper camera.


The Demco stay-n-play braking system has worked flawlessly for a full season of towing! The one time installation went smoothly and all components fit and functioned perfectly.
Very easy to use, connect to tow vehicle, flip a switch, and it's ready to tow. Disconnect from tow vehicle, flip a switch, it's ready for normal driving.
Would highly recommend this setup over other braking systems.


I am very deceived and feel I have bee fooled by the false affirmation, this is not proportional. I DO NOT RECOMEND THIS PRODUCT.
This system is nothing but proportional. All proportional wording or video is misleading should be removed. It's actually an on-off system. When braking light is on and the tilt sensor actually (on-off) is on the pump is on at full pressure pressing the brake until it bottoms out, period. The pump inlet creates a vacuum for the brake booster and the pump outlet is for the cylinder pressing the brake. All triggered by a simple switch. Nothing is regulated or proportionally controlled. Totally false information is provided here. Unfortunately the initial concept is good, but lacking the extra electronic pressure regulator and electronic control.
I had to set the angle switch so the system ONLY TURNS ON in the event of an emergency, otherwise it will brake fully and destroy your towed vehicle brake.
I am sure this review will not appear and will be deleted by the moderator. Too many good fake reviews...

Etrailer Expert

Brooke M.


I reached out to the manufacturer about this and they said what makes it proportional is the system works on two signals, the first signal needed is the brake signal that comes electrically from the coach, the second signal is when the towed vehicle feels forward inertia. The pump does not come on full, it slowly ramps up pressure, the more inertia felt the longer the system runs, the longer the system runs the more pressure that the system creates. The more pressure the system creates the harder the brake pedal is depressed. I also asked about the sensitivity issues you seem to be having and Demco said they have heard of that before when the sensor isn't installed level, as outlined on page nine of the instructions.

2014 Honda CR-V

After watching the excellent installation video I had very little trouble installing this product. I like the fact that it is a stay-in-play system that literally requires only the flip of a switch to activate. The major components are all installed out of the way, yet are still easily accessible. As for the braking system itself, I find it operationally excellent and believe this product choice was a great one.

2019 Jeep Wrangler

great kit for installing a supplemental braking system in my 2019 jeep wrangler. It takes several hours to install, but if you follow the instructions and watch the video, it's a pretty straight forward install. Just think it through and plan where you'll route the wiring and hoses. The hardest part was being flexable enough to mount the hardware to the firewall behind the brake pedal, but that's not a fault of the system.

2005 Jeep Liberty

I'm very pleased with this Stay-in-Play /DUO Braking System which I installed on my 2005 Jeep Liberty. I debated wheather I dared install it myself, but with the video instructions I decided that I could. I watched the video a couple of times, then followed it step by step during the installation, and it went pretty smoothly. One issue I had is that they changed the instalation of the LED indecator light, since the making of the video, so the parts did not come as described on the video. I do prefer the new method, as described in the installation manual, but it does require a toggle switch to turn it off. I installed one just below the Control Unit inside the car (see photo). I was also very impressed since, right after ordering the system, I found it for less on another web site. I emailed eTrailer about my disappointing discovery, and they credited me back the difference. GREAT COMPANY!

Robert P.


One year later, the system is still working great. Still very pleased.

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.

Herbert M.


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.


Erica G at etrailer was very helpful with managing my order and getting it to me w/ regular updates. The installation takes a lot longer than all of the etrailer 30 min videos but after it’s installed it’s easy to activate.


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.


Great product. Been towing my Jeep behind our Wanderloge using this set up for a year. Easy to install and works as expected. Keep in mind - these work on the brake light signal from the towing vehicle so if your tow vehicle is wired to flash your brake lights along with your turn signals when you turn on the hazard flashers, it will apply the brakes on the towed vehicle in sync with the hazard lights on the towing vehicle. So we learned not to use the hazard lights on the Bus when hooked up. If we are in steep mountains that slow us down, we just turn on the hazards in the Jeep and leave them on.


This braking system works great, much better and easier than other RV tow-ers that I run into from campground to campground. And although the install is not simple, the video instructions by Etrailer made everything go together without a "hitch"!

2020 Ram ProMaster 3500

Installing on 2020 Jeep Trailhawk :

Pic #0557 : Roadmaster Base Plate Kit , Demco Supplemental Braking System , Diode Wiring Kit , Demco Battery Charge Wire Kit

Pic # 0548 ,0551 , 0559 Had to adjust the bracket plate to line up with the upper bolt holes

Pic #6028 finished install , mounted the operating unit to the top fuse box cover using automotive Velcro . Air cylinder , controller and LED light installed . Aside from the base plate bracket not lining up with the upper bolt holes I would give it 4 stars . My son in law is a master at solving mechanical issues .

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!

2019 Jeep Grand Cherokee

had to make a bracket for under driver seat because the e brake would not allow the g-force controller to be place on the side panel.
the wires had to be extended to reach up to the controller in the engine compartment. Used a piece of aluminum plate to make a bracket mounted on strut frame that can easily be moved for other maintenance


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.

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!

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.


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!


I selected this item as an alternative to braking systems that sit in front of the driver seat and must be put in and taken out each time it is used. I like the fact that it is nearly undetectable once installed and works seamlessly. On installation the most difficult part was drilling the holes to screw the unit under the driver seat. The carpet being the primary problem in my experience, as it bound up around the drill bit.

2019 Ford Ranger

Intense installation. Take your time, do step by step per etrailer videos and demco instructions. Watch the videos several times so you are a sure you are ready to go. Then when your doing it, review the videos. You will be fine if you are mechanically inclined. For the vacuum booster connection on 2019 ranger do not get extra 3/4" id hose to tap into booster. It is too large to fit 3/8 ID hose and will cause a vacuum leak. You will get a brake system failure with a vac leak P050 cood. By 5/8" ID hose to tap in then your t-fittings with the 3/8" id hose will fit into the 5/8 " id hose and seal with clamps. No more vacuum leak or brake system failure warning. That is the only gotcha besides following the instructikns!

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.

Mike A.


Still working as expected, trouble free and no problems since the install.


Initial install of this was complicated and time consuming. Most difficult part was anchoring the cable to the pedal and firewall. The mount on the brake pedal interferes with the foot of people with larger shoes. This is because my car - Ford Fiesta - has very little room around the pedals. Works OK for me, but anyone with larger feet (size 12+) should consider the room around the pedal.


Easy to install. Perfect fit on my Honda 2014 CRV. Video was awesome. Great information on web site to aid in purchasing the correct one the first time.


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


The install was not easy. You need to follow the instructions in the videos. The product works very well and I would recommend it to anyone in need of a very good braking system.

Show More Reviews

See what our Experts say about this Demco Tow Bar Braking Systems

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    view full answer...
  • Recommended Fixed Supplemental Braking System for a 2017 GMC Terrain
    I recommend the Stay-IN-Play DUO, part # SM99251. It's a permanently installed braking system, like you're looking for, so all you need to do is flip a switch to activate it when you're ready to tow. Instead of using a cylinder and bracket that pushes your Terrain's brake pedal the DUO's actuating cylinder mounts to the brake pedal arm and connects to the firewall. The actuator doesn't get in the way and doesn't need to be removed or unhooked at all. Just flip the switch back off and...
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  • Getting Power to SMI DUO Braking System on 2017 Ford Focus
    I spoke with a representative of SMI, and they informed me that when using their Stay-IN-Play DUO, # SM99251, you should disconnect the positive cable from the battery, not the negative cable, despite what the owner's manual says. Then you should run the power wire between the positive post and battery disconnect. I also asked SMI about the braking system being activated when the turn signals are used. They said it was likely that this was happening because the sensitivity knob is set...
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  • Does SMI Supplemental Braking 2016 Ford Fiesta Know Difference Between Turn Signals & Brake Lights
    No as the SMI part # SM99251 is designed to recognize the difference between turn signals and stoplights when determining if the brakes or just the blinkers are being applied. I attached an install video for this braking system on a similar 2014 Ford Fiesta for you to check out as well.
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  • Will Heat be Concern with Demco SBS Duo Mounted Near Brake Booster
    Since you would plan to mount the Demco SBS DUO on a bracket near the brake booster that would be far enough from heat sources to not be an issue. You just wouldn't want it right near exhaust components as they get the hottest.
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  • Monitor Light for the SMI Stay-IN-Play Wont Turn On
    I looked through the owner's manual for the SMI Stay-IN-Play DUO Supplemental Braking System part # SM99251 and did not see any sensitivity settings for the monitor light. However, I do believe I know that the problem is. Do the brake lights in your toad illuminate when the vehicle is off? If they don't then you will need a stop light switch kit and I would need to know the year, make, and model of your vehicle in order to recommend one. If they do illuminate then odds are you may just...
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  • Installing SMI Stay-IN-Play DUO Braking System on 2018 Jeep Grand Cherokee
    It sounds like you are referring to the "Monitor Light" that is installed in the towed vehicle for the SMI Stay-IN-Play DUO Supplemental Braking System # SM99251 that you referenced. This bright LED strip is important and should be kept in your line of site, as it indicates that the towed vehicle's brakes are engaged. If you are pulling your Jeep and see this light illuminated in your rear view mirror when it shouldn't be (you aren't braking), you will want to stop immediately, as it indicates...
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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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  • Does SMI DUO Tow Bar Braking Kit Fit Gas Versions of 2018 GMC Canyon Same as Diesel
    The braking system is the same between the gas and the diesel versions so the SMI DUO part # SM99251 is going to install the same. The install video we have is for a 2015 which is mainly the same as your 2018 but there are a few little differences like you mentioned. The overall process though is the same.
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  • Installation Instructions for SMI Stay-IN-Play DUO Supplemental Braking System SM99251
    All of the flat towing braking systems that work with your 2011 Suzuki SX4 are shown on the linked page. For the SMI Stay-IN-Play DUO Supplemental Braking System # SM99251 the installation instructions are linked for you. I also linked an installation video (showing a different car) that will let you see the whole process.
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  • SMI Stay in Play Duo Supplemental Braking System Compatibility With 2017 Fiat 500
    The SMI Stay-IN-Play DUO Supplemental Braking System # SM99251 is a confirmed fit for your 2017 Fiat 500. It is my personal favorite system as well as a favorite with our installation team. This is because it is an easy installation that is extremely reliable. The system becomes plug and play after installation so you don't need to be concerned about adjustments or fit after the initial install. I'm confident you will be happy with this system in your Fiat. I've linked an installation...
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  • Recommended Supplemental Braking System for 2013 Chevy Sonic
    The supplemental braking system on your 2013 Chevy Sonic I highly recommend is the SMI Stay-IN-Play # SM99251 for this. This is a proportional braking system which is a one-time install which you can leave in so you'll never have to deactivate or re-activate it. The Stay-IN-Play uses an inertia sensor to detect when you decelerate which in turn will activate your Chevy's brakes. This system is made in the USA and comes with a 5-year warranty. I've added links to a number of video reviews...
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  • Does Demco SBS Stay-IN-Play DUO Work with Manual Transmission Vehicles
    Yes the Demco SBS Stay-IN-Play DUO Supplemental Braking System # SM99251 that you referenced does work with vehicles that have a manual transmission.
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  • Does Check Valve of SMI DUO Braking Kit Have to Be Used to Install in 2018 GMC Canyon
    You do have to install the check valve of the SMI DUO part # SM99251 to your 2018 GMC Canyon. What you sent in a picture of doesn't appear to be a check valve. It looks like it may be a tee valve or possibly a vacuum reduce so you would want to install the check valve of the DUO like the install instructions indicate as well as install video I attached that shows this installed on a similar Colorado as your Canyon.
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  • Troubleshooting Stay-In-Play DUO on 2016 Jeep Cherokee with Start/Stop System
    I reached out to the manufacturer and they said the Stay-IN-Play DUO Supplemental Braking System # SM99251 will work fine with your 2016 Jeep Cherokee with start/stop if it is installed correctly. The start/stop system won't be an issue and will function properly. What your error code and issue is showing is that there is a vacuum leak caused by either a part issue or wrong positioning. This can be due to a check valve being installed backwards for instance. The black part of that valve...
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  • Why Isn't The Demco SBS DUO Supplemental Braking System Activating When At A Stand Still
    The Demco SBS Stay-IN-Play DUO Supplemental Braking System - Proportional # SM99251 has an inertia sensor that detects deceleration and signals the system to activate the brake pedal with a proportionate amount of pressure. Because of this if you're sitting at a stand still and trying to test the system it will not activate. I recommend slowly rolling through your neighborhood to test the braking function of the system.
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  • How does the Demco Stay-In-Play's break-away switch attach to the vehicle?
    The Demco SBS Stay-IN-Play DUO Supplemental Braking System - Proportional # SM99251 comes with a bracket that is already attached to the break-away switch. It has a bolt hole in it to easily attach to the front of your 2021 Jeep Cherokee. (I attached a photo of this switch installed with a bolt/screw.) There is no other bracket to attach this to your vehicle's front end.
    view full answer...
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