How to Make the Airline Connections on the SMI Supplemental Braking System Part # SM99243
Updated 04/06/2018 | Published 04/05/2018
Question:
Looking to purchase SMI Air Force One braking system for my 1998 Holiday Rambler Endeavor diesel pusher with Freightliner chassis . However am not sure which air lines to tap into. From front of coach is one approx.1/2 in. light green supply line? and one approx. 1/4 in. light green line running to drivers side valve body and one approx. 3/8 in.metered? light green line running from drivers side valve body to passenger side valve body. There are no black lines. There are also 2 red lines running from front of coach into the passenger side valve body. There are no red lines run between the valve bodies.
asked by: Bob
Expert Reply:
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 push-to-connect air line t-fitting. Don't forget to drain the coaches air tank before severing this line.
The metered-air line is a 3/8" diameter hose (usually black but not always) that will be located on the spring-brake/quick-release valve (see second photo). You can identify this valve by looking for the label which should read “spring” or “emergency”. You will again need to cut the line in half and install the supplied push-to-connect air line t-fitting.
Unfortunately, the color of the airlines will not always be a constant therefore you will need to identify the diameter of the line and source before making the connection. If you are weary of installing the system yourself I strongly recommend taking the motorhome to a quality auto mechanic at your local RV service center as they would be able to install the unit for you.
Product Page this Question was Asked From
Demco Air Force One Flat Tow Brake System for RVs w/ Air Brakes - Proportional
- Flat Tow Brake System
- Brake Systems
- Proportional System
- One-Time Setup
- Vehicle Battery
- Fixed System
- Power Assist Brake Compatible
- Air Brakes
- Indicator Lights
- Demco
more information >
Featured Help Information
Instructions
Continue Researching
- Q&A: Flat Tow Setup For 2025 Ram 1500 Being Towed by Tiffin Motorhome With Air Brakes
- Shop: Blue Ox Avail Non-Binding Tow Bar - RV Mount - 2" Hitch - 10,000 lbs
- Shop: Vehicle Tow Bar Wiring
- Search Results: blue ox apollo
- Search Results: blue ox rock guard
- Search Results: tow bar
- Video: Review of Blue Ox Towed Vehicle Battery Charge Line Wiring Harness - BLU44ER
- Shop: Blue Ox Towed Vehicle Battery Charge Line Wiring Harness
- Shop: Roadmaster 4-Diode Universal Wiring Kit for Towed Vehicles - 7-Way to 6-Way Coiled Adapter Cord
- Shop: Replacement Reed Switch with Bracket for Demco Air Force One Flat Tow Brake System
- Video: Demco SBS Air Force One Coach Air Kit Installation - 2021 Freightliner XC-Series
- Video: How to Install the Demco Tabless Base Plate Kit - 2024 Ram 1500
- Video: How to Install: Blue Ox Base Plate Kit on your 2022 Ram 1500
- Video: Hands-On with the Blue Ox Avail Non-Binding Tow Bar
- Shop: Base Plate for Tow Bar
- Video: All About the Roadmaster Battery Charge Line Kit for Motorhomes
- Shop: Blue Ox KarGard Protective Shield for Towed Vehicles
- Shop: Blue Ox 6-Diode Tow Bar Wiring Kit for Towed Vehicles with Progressive / Animated Tail Lights
- Shop: Heat Shield for Roadmaster Tow Defender Protective Screen
- Q&A: How To Wire Replacement LED Monitor Light for Demco Air Force One and Stay-IN-Play Braking System
- Q&A: How to Test Reed Switch of Demco Air Force One
- Video: Roadmaster Battery Charge Line Kit for Motor Homes Installation - 2020 Coachmen Mirada Select Motorh
- Q&A: Recommended Flat Tow Parts for a 2025 Jeep Wrangler Sport Towed By A Tiffin RV w/ Quick Connect Air
- Q&A: Easiest Setup For Flat Towing a 2024 Ford Maverick With Demco Commander Tow Bar and Brake Buddy
- Q&A: Demco Air Force One Braking System For Factory Prepped Tiffin RV
- Q&A: Recommended Flat Tow Setup For 2022 Ford Escape Plug-In Hybrid Using Blue Ox Tow Bar
- Article: Trailer Wiring Diagrams
- Article: Must-Have Flat Towing Components
- Article: Best Vehicles to Flat Tow Behind an RV
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
on Flat Tow Brake System
