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Demco Air Force One Supplemental Braking System for Motorhomes with Air Brakes - Proportional

Demco Air Force One Supplemental Braking System for Motorhomes with Air Brakes - Proportional

Item # SM99243
Our Price: $1,329.00
You Save: $511.71
Tow Bar Braking Systems

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This truly proportional braking system uses the air pressure from your RV's brakes to apply the brakes in your towed car in the same manner. Low-profile design installs out of your way and is always at the ready. Great Prices for the best tow bar braking systems from Demco. Demco Air Force One Supplemental Braking System for Motorhomes with Air Brakes - Proportional part number SM99243 can be ordered online at or call 1-800-940-8924 for expert service.
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Demco Tow Bar Braking Systems - SM99243

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

This truly proportional braking system uses the air pressure from your RV's brakes to apply the brakes in your towed car in the same manner. Low-profile design installs out of your way and is always at the ready.


  • 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
  • Truly proportional system uses the air pressure from your RV's brakes to apply the brake pedal in your car
    • Coiled air hose connects air assembly in RV to operating unit in towed car
  • No false braking
    • Coach air brakes must be activated for system to apply towed car's brakes
  • 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 you are driving
      • Low-profile design of operating unit allows for more room in the engine compartment of towed car
      • System automatically functions when towed vehicle is connected to RV
  • LED coach notification system illuminates when the towed vehicle's brakes are applied
    • Reed switch on the actuator ensures an accurate reading
  • Vacuum-assisted function of towed car is activated with air from the coach brakes
    • 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
  • System meets FMVSS safety guidelines for motor homes that use air brakes
  • Necessary installation components and an instructional CD included
  • Made in the USA


  • Application: motor homes with air brakes
    • Can accommodate air-over-hydraulic brakes - additional 1/4" DOT air line (not included) may be required
  • Coiled air hose length when fully stretched: 7'
  • Breakaway cable length when fully stretched: 7'
  • 5-Year warranty

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, Truly Proportional Braking

Air Force One is a proportional braking system. When you apply the brakes in your motor home, the system will engage your towed car's brakes at the same time and with the same pressure as those in your motor home, creating synchronized braking.

To achieve this proportional braking, Air Force One ties into your coach's air brakes. The patent-pending process uses air pressure from your coach's brakes to depress the brake pedal in your towed car. The result is uniform, real-time braking that mirrors the slowing or stopping action of your coach. Whether you lightly tap the brakes in your RV or apply them hard in a panic situation, your towed car's brake pedal will be applied in the same manner.

Many other proportional systems activate the towed car's brakes based solely on inertia. With this kind of setup, any activity that affects the forward momentum of your towed car - from the coach actually braking, to driving over a pothole - can activate the supplemental braking system and apply your towed car's brakes. This potential for false braking, which can occur simply from driving over uneven terrain, can create a rough ride for you in the RV and can also wear out your towed car's brakes over time. Air Force One is different, though. Because it is tied into your coach's brakes and is not dependent on inertia, this system activates only when you apply the brakes in your RV, so there is no false braking.

Permanent Installation with Concealed Components

Once you install the Air Force One system, it stays concealed and out of your way - both in the RV and in the towed car. Unlike systems that require you to keep the actuating box under the seat or in the trunk of your towed car, Air Force One does not take up valuable storage space inside of your car. And the components that install on your RV all remain hidden beneath the vehicle so that no room is taken up in its interior either. Because the entire system installs permanently, there is no need to constantly set up and remove this system. You never have to worry about where to store a bulky actuator box when you're not towing. And while most of the components do remain on your vehicle and RV at all times, none of them will interfere with normal driving or braking.

Coach Air Connection Assembly

Because Air Force One uses air to activate, it is a natural choice for diesel motor homes that have air brakes. The coach air connection assembly taps into your RV's air brakes and delivers the air necessary to activate the towed car's brakes through the included coiled air hose. The valves on the coach air connection assembly ensure precise airflow.

Pressure Protection Valve

A 1-way check valve collects air from your RV's brake lines so that it can power your towed car's brakes. This pressure protection valve also ensures that your RV's air lines maintain the same amount of pressure so that the braking in your RV is not affected.

Relay Valves

Metered air from the coach's brakes connects to a service relay valve. This relay valve collects air from your RV's brake lines so that it can power your towed car's brakes. When you activate the brakes in your RV, the delivery relay valve releases the appropriate amount of air to the operating unit in your towed car.

The coach air connection assembly is best mounted in a location on the RV where the air lines will not be near direct heat sources or moving parts, such as in front of the rear axle.

Note: Air Force One is designed for motor homes that have air brakes, but it will also work with RVs that have air-over-hydraulic brakes. Additional parts (not included) may be required for installation on RVs with air-over-hydraulic brakes.

Operating Unit

The operating unit, which mounts in your towed car, receives air from the coach air connection assembly. The unit then diverts a matching amount of air through a hose to the actuating cylinder that mounts on your towed car's brake pedal. That air activates the cylinder so that it applies proportionate braking pressure.

The unit goes under the hood of your towed car, so it is out of your way and always ready. Because this system is a universal fit, you can remove it from your towed car and reinstall it in a different car or truck if needed.

Actuating Cylinder

Small Cylinder

The actuating cylinder depresses your towed car's brake pedal upon receiving the air that is delivered 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.

Coiled Air Hose Connection

Coiled Air Jumper

The coiled air hose, also called a jumper, connects your towed car to your RV by connecting the operating unit to the coach air assembly. When you are ready to hitch up your car and tow it, simply hook up the coiled air hose at the same time as you hook up your tow bar.

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.

Air Force One reactivates the vacuum-assist function of your car's brakes when it's being towed, even though the towed car's engine is not running. As a result, the actuating cylinder does not need to apply extreme force to the brake pedal to achieve proper braking. The operating unit ties into your towed car's vacuum line with a tee so that it can use the air pressure from your RV to create the vacuum your car needs to brake gently. As a result, no additional vacuum pump is required to create the vacuum-assist function for your towed car's brake pedal. Air Force One 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

AFO Light in Towed Car

Included is an LED indicator light for safety and peace of mind. This LED, mounted in the toad and visible in your backup camera, will light up whenever your toad is actively braking. It's a simple way to keep tabs on when the system is working properly or if something goes wrong.

Most supplemental braking systems have a method of letting you know you when they activate, but not all of them are checking if the toad is actually braking. There could be an error where the system is activating without the toad braking, or even that the brakes are staying on continuously when they shouldn't be, but you won't know it until the damage is already done. This indicator, however, connects directly to a reed switch on the actuator so it only lights up when the pedal is depressed.

Air Force One Monitor Install

You can attach 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.

If there's a strong glare on your toad's windshield, the LED light strip can be hard to see. The wireless Coachlink system (SM99945 - sold separately) is a great solution to this problem; the monitor mounts right on your RV's dashboard so it's directly in view. This is a great add-on for convenience and peace of mind.

AFO Breakaway

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. A reserve air supply will then apply your towed car's brakes. This system also has "total coach protection" built in. If there is separation, the RV's air supply is sealed off, so its brakes will continue to function as normal.

Air Force One meets Federal Motor Vehicle Safety Standard (FMVSS) guidelines requiring that supplemental braking systems use a separate air supply and activation relay valve.

9599007 AFO115 Demco SBS - (Formerly SMI) Air Force One Supplemental Proportional Braking System

Replaces Demco SBS SM99202 and SM99243


Installation Details SM99243 Installation instructionsAlternate Instructions SM99243 Installation instructions

This Product Fits The Following Vehicles

Customer Satisfaction Score:

Customer Reviews

Demco Air Force One Supplemental Braking System for Motorhomes with Air Brakes - Proportional - SM99243

Average Customer Rating:  4.9 out of 5 stars   (310 Customer Reviews)

This truly proportional braking system uses the air pressure from your RV's brakes to apply the brakes in your towed car in the same manner. Low-profile design installs out of your way and is always at the ready.


I wouldn't use anything else! Once this system is installed it's literally plug-and-play. Nothing to move or install into the car, each time you tow. Just plug it into the coach's air break system and you're done. Install video from etrailer made it even easier to complete.

You do need a bit of mechanical guidance/assistance as you're connecting to both your vehicles and coaches breaking system but it has worked flawlessly for over 11,000 miles and in some pretty intense traffic.


The Air Force one was not an easy install for me because I’m old and I don’t get around like I used to but it was not impossible. However, in my opinion, it is the best supplemental braking system for flat towing. The best part about it is my Allegro Bus came with the system already installed on the coach and once you install it on your towed vehicle you don’t have to deal with any of that to get on the road. If it takes me more than ten minutes to hook everything up and get in the coach ready to drive away then I've done something wrong.

2014 Honda CR-V

AF1 is amazing so far. I did the installation by myself. I have a 2014 Honda CR-V and bought it for towing. Watching the video helped me through it. The car installation portion was pretty straight forward. The video is better than the instructions overall, but I read through the entire instructions before beginning. I was able to install the RV tank without putting the rig on a lift. Depending on how big you are and flexibility, it can be done with the RV on the just takes longer. Also, I would recommend knowing where you are going to mount your RV tank. I mounted the tank near the rear and didn’t have enough brake tube after doing the car. Picked up an extra 20 ft at Autozone or order the tube with etrailer.

The customer service center is very helpful too. Many thanks to Mariah for the outstanding assistance. Finally, I would say that if you order the brackets to mount the emergency brake away for your car, you may have to cut them down with a grinder. It is so much nicer not putting the brake buddy in the car now. Looking forward to enjoying it on trips. I drove the rig about 20 miles yesterday, and the light came on and I honestly couldn’t tell the car was back there other than looking in the video and seeing the light on the car during braking. Highly recommend this unit.

Darryl W.


5.0 Product is working great! No issues. Minor adjustment to brake cable after a year. It took 5 mins.


I believe the AFO is the best supplemental braking system for air brakes on the market today. Probably the most expensive also. A lot of work to install but a good system that is truly proportional and safe to use with an air brake system.

Bruce P.


We have used our AFO for over 12,000 miles towing a 2018 Chevrolet Colorado. It seems to be working fine but is really hard to know for sure. It is difficult to see the LED light strip in the camera during bright daylight. When I installed the AFO, etrailer was very helpful even returning my call on a Sunday. I also added a plastic stub next to the connectors on both the RV and toad that very conveniently stores the plastic cover when the brakes are not connected so they do not get lost. I tried to contact etrailer with my simple improvement but no one seemed interested.


Installation was easy, compact and out of the way. Had a little problem finding controller location due to clearance. Ended up using velcro on top of the fuse box to hold the controller in place.



Questionable? This year it Felt like the truck in tow was pushing me during mid to heavy braking. Pulled over a couple of times to verify pedal was being pushed down. Verified vacuum lines from your system to the brake vacuum line was tight. It acted like the vacuum assist was not working. I need to find time to ask you about this problem.

Etrailer Expert

Katrina B.


So, it seems that this is going to be better diagnosed through troubleshooting with the manufacturer. I have sent you Demco's contact information and their hours of operation in a seperate email.

2012 Saturn Relay

"Out of sight, out of mind" would be the best description I could offer for the Air Force One supplemental braking system! When properly installed, it's effective as well as quick and easy to hook up. Connect the tow bar, safety cables, safety switch cable, tow plug and air line, you're done! Five minutes at most.

I did add a couple of features to my towing system:

1. Using a relay and the extra wire in the connector to the coach, I installed the LED indicator strip on the dash of the coach; no need to rely on the back-up camera to verify operation of the brake cylinder. Coaches that have a tow connector are usually equipped with a power wire to the cab for electric brakes - this wire is a good way to get the indicator signal to the front of the motorhome.

2. I used the 12 V power connection from the coach to connect a charging wire to the car battery to ensure it would not discharge; I used an auto-resetting breaker with a rating below the glass fuse in the 12 V circuit to prevent a fuse from blowing if the charge current gets to high.

In all, a great investment! I have an article I wrote on the install if anyone is interested.

2016 GMC Canyon

Vehicle 2016 GMC Canyon Diesel.
of the SMI Air Force One supplementary braking system was not too difficult. The instructions from SMI were good as was the video from etrailer. The only reason that I didn't give it a 5 star is because the air cylinder installation on the brake pedal was complicated by an unusual shape of the brake pedal arm. I eventually found a solution.
Tapping into the truck's vacuum line was a little difficult but the kit included everything I needed to T into the vacuum line and install the check valves.
All in all not a bad installation, this summer we'll see how it holds up.

Ford F-150

Very pleased with the Air Force One braking system. I installed it myself on my Newmar Dutch Star and it works great for towing my F150.


I’ve fitted it to my Jeep Wrangler then taken of and fitted to our new Jeep Grand Cherokee. Works perfectly . I had used our 53ft coach without it and in an emergency stop, was a problem stopping in the rain. Now we have had a couple of fast stops and it works great, would be without it.


Took some time to route the lines but the system works well


Came with everything I needed to install it. Great quality and works fantastic!

Jon M.


Works great!


I installed it myself, followed the eTrailer installation video. I have used it a year, works great, have put over 3000 miles on it. No issues. Struggled with using a portable brake system and decided to do it right. It was the right choice.



Perfect, way better that the portable device


This braking system has been nearly flawless for me since installation.
Only tow coomplaints to speak of, as follows:
1. During install of the firewall screw for the acutator, the screw ended up causing a short in my vehicle. I had to spend many hours troubleshooting and Demco support was adamant it was not their products fault.
2. The actuator has gotten sticky over time and does not reset to the correct location after braking, causing the light to stay on longer than it should.


Great product and easy to follow detailed instructions.


Works confidently! The activation cylinder on brake pedal arm rattles and doesn't adjust well to moving brake pedal to driver position. It also lights up the LED on my rear view mirror when not being towed.

2004 Chevrolet Avalanche

Pulled entire length of route 66 and then some. We had absolutely no issues with all of our etrailer equipment. Thanks for all of your help.

Ford Ranger

This system has worked great for my flat towing of my Ford Ranger. Had my local dealer install the system for me and have had not one single issue with the operation.



After one year and more than 10k miles have not had a single problem with the Air Force One braking system on my 2019 Ford Ranger.


We love our Air Force One braking system. The confidence it was done right by etrailer allows us to tow our 4x4 van without worrying about it!

2022 Jeep Grand Cherokee L

Simple installation. Very good instructions from Demco.

2014 Jeep Wrangler

Just finished a 10,000 mile trip trailering a 2014 Jeep Wrangler with Air Force One braking system and we are very satisfied with the product. No issues or failures and once installed, it is very easy to use. We can connect and disconnect from the Air Force One and our Blue Ox towing system in 2-3 minutes.

Joe T.


After a year, we are still happy with the AF One. We had one issue where it didn’t work and it turned out we let a little grime get into the air fitting. Took some time to figure it out but we cleaned with compressed air and the problem went away. Lessen learned it to keep rubber covers on the air fittings when not in use.

2004 Jeep Wrangler

Very easy to install and works fantastic !!!


This is the best system for your towed vehicle.


It would be nice if the instructions told how the AFO was designed to work in detail. Most installers have an opinion but to have it explained would be a plus. Like the small air tank in the control box etc.

2016 Jeep Wrangler

SMI Air Force One was the choice I made when we outfitted our 2016 Jeep Wrangler Unlimited last year. I can honestly say, without any hesitation,...this was the best choice ever. The installation was very straight forward. I was reluctant to cut my coaches brake lines...but the technicians at SMI were very helpful. I emailed them a picture of the brake lines that I had identified per the instructions, and wrapped a piece of colored electrical tape around the lines to identify them. The SMI techs wrote back within 20 minutes and confirmed that I had correctly chosen the correct air lines for splicing into. The fittings where a breeze to install. The system has performed flawlessly...and it works so well ---- if it weren't for a video camera view on my dash...I wouldn't even know the Jeep was back there.

When I go to hook and unhook the Jeep. I keep my components in a canvas bag. It contains my Safety cables for the tow bar, lighting umbilical, and the two SMI parts...a coiled quick connect air line, and a safety breakaway cable. The other components of the system stay in lugging them around. They are totally out of sight.

If you have a coach with Air Brakes...this, in my opinion, is the best thing going. Proportional braking...directly metered by your coaches signal line. The system is robust...and includes it's own ping tank, and D.O.T. approved metering valve. I feel it's the safest...and best performing braking system built for a towed vehicle PERIOD.


I ordered an Air Force One breaking system one year ago, for my 2019 Allegro Bus 45OPP, and my 2012 Honda CR-V.
I paid $1080.00 with free shipping from E-Trailer. The unit arrived in perfect condition. I installed the system myself, in about three hours on the Motorhome. I had previously ordered a special hose/ tube cutter. The only part of the installation that was a little intimidating was cutting the correct air lines on the coach, however after viewing the installation video everything was made clear.
The install on the Honda took about two hours, I did have to call the people at E-Trailer , but they cleared up my questions.

Show More Reviews

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

  • Troubleshooting the Brake Lights Not Coming on in my Flat Towed Vehicle
    It sounds like you are more likely having and issue with your tow bar wiring rather than the Demco SBS Air Force One Supplemental Braking System # SM99243. You can test this by testing your Air Force One system. Depress the break and verify that the LED indicator light is coming on and that the actuator is pulling the brake pedal in your towed vehicle. If that is happening, then the Air Force One is working properly. The Air Force One is not what provides power to illuminate your brake...
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  • How Many Amps Does Demco SBS Air Force One Braking System Draw
    I reached out to Demco, who told me the Demco SBS Air Force One Supplemental Braking System for Motorhomes with Air Brakes # SM99243 draws less than 1 amp. They told me the the only power used is to light up an LED on the back of the towed vehicle's review mirror to indicate that the brakes are being applied in the towed vehicle, and that is only when the brakes are applied. I have added a link to a video review for you to check out as well of the Demco SBS Air Force One Supplemental Braking...
    view full answer...
  • Keeping Water Out of Air Force One Braking System in Automatic Car Wash
    I spoke with my contact at Demco and he insisted that while it was unlikely that the cap that goes over the air connection on the # SM99243 would come off in an automatic car wash, they recommend using a zip tie around the cap on the connection to keep it secure. Typically the cap would only come off when they are worn down and stretched out. Using a zip tie around the base will keep even the most worn down cap from coming off while going through an automatic car wash.
    view full answer...
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  • How Installed SMI Air Force One Receives Power While 2016 GMC Canyon Being Towed
    The power and functionality requirements of the Air Force One System, Item # SM99243, are taken care of when it is directly attached to the vehicle battery during installation. Everything will still function even if the negative cable is off of the battery because only the positive terminal and a ground location are needed The Air Force One works by engaging the brakes for a towed vehicle when it receives air from the coach air connection. It diverts a matching amount of air through...
    view full answer...
  • Is Air Force One Supplemental Braking System Compatible with Air over Hydraulic Motorhome Brakes
    Yes, the Air Force One part # SM99243 that you referenced is compatible with air over hydraulic brakes like what your 2003 Safari Cheetah has that is built on a Roadmaster M4R Series Chassis. I attached a review video for this system for you to check out as well.
    view full answer...
  • Video of Install for SMI Air Force One Supplemental Braking System on 2017 Ford F-150
    We are not affiliated in any way with installers apart from our own, which are located in Wentzville, MO so there is not a list I can offer for installation of the SMI Air Force One Supplemental Braking System for Motor Homes with Air Brakes # SM99243. However, if you make some calls to certified mechanics or shops in your area you are very likely to find someone who is qualified to do the installation. I did add a pair of links to video installations showing this system being installed...
    view full answer...
  • Finding Where to Connect Air Lines to Motorhome to Install SMI Air Force One
    When installing the SMI Air Force One Supplemental Braking System For Motor Homes with Air Brakes # SM99243 you will need to find the supply air line and the metered air line on the motorhome. On the Monoco Knight 34foot Road master chassis 2003 model the larger 5/8 inch line is the supply air line, and the smaller 3/8 inch line below the supply air line is the metered air line. See attached picture to see them pointed out. It sounds like what you found so far is not the service relay...
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  • Air Force One Supplemental Braking System Actuates Vehicle Brakes When Not Attached to RV
    I spoke with my contact at SMI, the manufacturer of the Air Force One braking system. He had a few possibilities that he recommended you have checked. Where the cable that joins the actuator cylinder on the brake pedal, make sure that there's about 1/4 to 1/2 an inch of slack in the cable. Also, if the vehicle has adjustable pedals, make sure that the pedals are move as close to the seat as they'll go when the tension on the cable is set. This procedure is outlined in Step 7 of the installation...
    view full answer...
  • Compatibility of Flat Towing 2014-2016 GMC Terrain and SMI Air Force One Braking System
    The GMC Terrain models from 2014 through 2016 can call be flat towed four wheels down, but it is recommended to have a speed restriction of 65 mph on all of these models when doing so. It is also recommended to start the vehicle and let it run for 5 minutes prior to towing and at each fuel stop. This gets the moving components properly lubricated to prevent damage. You will also want to let the engine idle for 3 minutes or more prior to driving after towing it. You will also want to...
    view full answer...
  • Can SMI Supplemental Braking System be Used with 2006 Tiffin Allegro Motorhome
    Our fit guide info for the SMI Air Force One Supplemental Braking System for Motor Homes with Air Brakes # SM99243 is relative to vehicles that are getting flat towed. You'd be using the Tiffin Allegro bus as a tow vehicle and not a towed vehicle which is why it's showing up as "not a fit". As long as your Allegro as air brakes this kit will work well on it.
    view full answer...
  • Will Air Brake System Apply Supplemental Braking System Brakes
    Supplemental braking like the SMI Air Force One # SM99243 will start trying to activate the towed vehicle brakes when the brake lights of the tow vehicle apply. So if the engine brakes apply the brake lights then yes the system would start working to stop the vehicle.
    view full answer...
  • Where to Mount Module of SMI Air Force One on 2019 Jeep Cherokee Latitude
    The picture is somewhat hard to understand what's going on, but it looks like they mounted the module of the SMI Air Force One Supplemental Braking System # SM99243 horizontally in front of the radiator. It would appear it wouldn't affect the air flow to the radiator too much but I'd probably keep an eye on the fluid temperature gauge. As long as it's securely mounted it would be fine. I attached a picture that shows where we mounted the box on a similar 2018 Cherokee as well. The install...
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  • SMI Air Force One Module Dimensions
    The overall length of the module that comes with the Air Force One # SM99243 is 10-1/2 inches from handle to handle but the actual box part is 8-1/2 inches. It is 5-3/8 inches wide and 1-1/4 inches tall. Check out the picture I attached to see all of the dimensions.
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  • Do I Need the Air Tank for the Demco Air Force One in a 2002 Prevost?
    You're welcome! No, you won't have it. That's a newer addition to motorhomes. You'll need to install the air tank that comes with the Demco Air Force One Supplemental Braking System for Motorhomes with Air Brakes item # SM99243.
    view full answer...
  • Potential Issues if a Demco Air Force One Braking System is Engaging the Parking Brake on a Sierra
    I have not come across this being an issue when using the Demco Air Force One Supplemental Braking System # SM99243 in your 2023 GMC Sierra 1500 before. So I went ahead and reached out to the manufacturer to see if they have come across this before and I have included what they were able to tell me below. "It sounds like when the customer disconnects the negative cable, the truck is still finding a ground through either the tow bar or lighting cables. As a result the truck acts as if...
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  • Recommended Supplemental Braking System to Flat Tow a Subaru Forester
    The brake controller you mentioned is utilized when towing a trailer or a tow dolly, but when you flat tow a vehicle a different system is used that will utilize your motorhome lights but will also utilize the braking inside your towed vehicle. For your Subaru Forester, I recommend the Air Force One, part # SM99243. It's great for motorhomes with air brakes like your Winnebago because it only engages the Subaru's brakes when the air brakes are activated and not when the brake lights...
    view full answer...
  • How to Make the Airline Connections on the SMI Supplemental Braking System Part # SM99243
    There are two airlines that must be spliced into on the coach which will then run to the air tank assembly included with the SMI Air Force One Supplemental Braking System part # SM99243. One of these lines is for supply-air and the other is for metered-air. The supply-air line is a 5/8" diameter hose (usually green but not always) which goes from the service relay valve to the braking air tank (see first photo). Once you find this line you will need to cut it in half and install the supplied...
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  • How Does The Demco SBS Work On A Vehicle With An Electric Master Cylinders Without Vacuum Assistance
    I contacted the manufacturer in regards to the Demco SBS Air Force One # SM99243, and they explained that the reason they tap into the vacuum system of a vacuum brake booster is that their system creates vacuum and they can keep the power brake booster active during tow. If your vehicle does not have a vacuum brake booster they make adjustments with the operating unit, for hydro boost systems they block off the vacuum port and the exhaust port of the unit. For electric assist units, it...
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  • LED Monitor on Demco SBS Air Force One Supplemental Braking System Stays Illuminated
    You'll want to review the installation of the actuator read switch for the LED monitor, as incorrectly installing it can cause it to ground out, in which case it'll stay illuminated all the time. The procedure is described in step 7, on page 25 of the instructions. I've inked you to the installation instructions for the Air Force One # SM99243 braking system.
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  • Estimated Installation Time for SMI Air Force One Braking System
    I reached out to my contact at SMI and he said that for both the RV and your 2017 Chevy Silverado you're looking at a total install time of around 5 to 6 hours for the Air Force One Braking System # SM99243. I have attached an installation video on the 2017 Silverado that you can use for reference along with the written manual.
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  • Does the Air Force One Activate the Towed Vehicles Brakes When the Exhaust Brake Is Used
    The Demco Air Force One Supplemental Braking System # SM99243 is actually the perfect solution for you since it does not engage the brakes on your toad when the brake lights on your coach are lit; it instead relies on the the coach's air brakes to be activated and will prevent false braking that occurs with other systems that react to the brake light signals. Because of this, when you use the exhaust brake instead of the coach's air brakes, it will not create a situation where the toad's...
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  • Troubleshooting Light Indicator of SMI Air Force One that Stays on All the Time
    The switch on the actuator for the Air Force One # SM99243 is a reed switch. It detects the presence of a magnet on the inner part of the actuator. When the magnet is near the switch the light is off. If you removed the reed switch and used a magnet you could simulate the activation and determine if the problem is the switch or the actuator. You also should try moving the switch on the actuator as it may need adjustment. If possible move the switch away from the air line as much as you can.
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  • Installing SMI Air Force One Supplemental Braking System on 40 Foot Dutchcraft on Spartan Chassis
    When installing the SMI Air Force One Supplemental Braking System For Motor Homes with Air Brakes # SM99243 you will need to find the supply air line and the metered air line. On the Dutchcraft motor home on the Spartan Chassis the larger 5/8 inch line is the supply air line, and the smaller 3/8 inch line below the supply air line is the metered air line. I have attached a photo showing witch line is the supply and which line is the metered.
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    Image 1 for
  • SMI Air Force One Brake System Air Line Connection in Coach Recommendation
    In the install instructions for the SMI Air Force One system part # SM99243 that you referenced the correct line to use for the Spartan Chassis is pointed out. I attached that picture. The line to use is the coach's supply air hose. This line goes from the service relay valve to the braking air tank. It is 5/8 inch in outer diameter. This line is normally green and should not be confused with the treadle valve hose which is 3/8 inch in diameter.
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