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Demco SBS Air Force One Supplemental Braking System Installation - 2015 GMC Sierra 2500

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How to Install the Demco SBS Air Force One Supplemental Braking System on a 2015 GMC Sierra 2500


Hey everyone, how's it going Today, we're gonna be going over and showing you how to install the Demco Air Force One supplemental braking system, here on a 2015 GMC Sierra 2,500. So a supplemental braking system is required in nearly every state for vehicles over a certain weight. So it's gonna be a good idea to use one for your towing setup. Now, a supplemental braking system, what it does in its most basic form, it pretty much transfers the brakes from your motor home to the towed vehicle. So the reason this is important is, some of our towed vehicles, especially our larger truck here, they're gonna put strain on the motor homes brake. It's gonna wear the motor home's brakes faster and it's not gonna allow us to come to a smooth and effective stop, as we would normally when we're not towing.

So therefore assisting the motor home's brakes by applying the brakes in our towed vehicle here, it's gonna make for an overall much better towing experience. So there are a few different types of braking systems on the market. Pretty much two main types. We have portable systems and then we have more of the permanent install systems. So the Air Force One is definitely gonna be more towards the permanent side.

Not to say that it can't be removed. But essentially what this means is, the system is gonna stay installed on the vehicle, even when we're just driving around town. It's gonna be very minimal setup procedure when we do need to tow the vehicle. As opposed to a portable braking system, we're gonna be removing this and installing it each time we need to tow. So it's a little bit more involved in regards to the setup.

The installation, however, is obviously gonna be a little bit easier for the portable system. So the Air Force One is actually a proportional braking system. Now what this means is, we're gonna get a braking force sent to the towed vehicle, in an amount proportional to that of how we're pressing the brakes in the motor home. So say we're out on the highway, somebody cuts in front of us, we really need to slam on our brakes, we're gonna get a lot of braking force sent to the towed vehicle. Now on the contrary, say we're just moseying around town, coming to a slow stop at a stoplight, we're not gonna get a lot of force sent to the towed vehicle.

So with our kit here it's gonna be composed of a few different components. We have the coiled air tube that goes between the towed vehicle and our motor home. And we also have a breakaway switch here which would pull the brakes, activate the brakes, on the towed vehicle here, should it become disconnected from our motor home. So underneath the hood here, we have the operating unit. So the operating unit is pretty much the brains of the operation. This is where all of our connections are gonna go through before they're transferred from the motor home inside the vehicle. So then inside the vehicle here, we're gonna have a couple other things. You can see we have our air cylinder here. So this is actually anchored to the firewall. So when the operating unit receives the signal, it's gonna depress the pedal, using the actuator there and the anchor point on the firewall. So just to give you a quick demonstration here, we'll hold the cylinder and we'll press in on the pedal. And that's pretty much gonna mimic the operation there when we're pressing the brakes in our motor home. So then last but not least, we have a monitor light which is gonna be mounted inside the towed vehicle. This is simply just an LED light that's gonna go off each time the brakes in our towed vehicle are being depressed. We can show you that now. So in regards to installation, this one isn't too bad. It is pretty straightforward and it's definitely gonna take you some time, but I really wouldn't say anything is particularly difficult. Let's go ahead and walk you guys through this all now. So to start off our installation here we need to find a place to mount our operating unit. Now there's more than one place we can mount this but really the best location that we found throughout, is to use the fuse box and attach it directly to the lid. So if you wanna go ahead and make sure that the fuse box lid can still be removed with the operating unit installed. But we went ahead and tested that for you guys and there isn't any issues. So in order to mount it to the fuse box lid, you had to drill four holes into the plastic lid. So before we attach the operating unit to the fuse box lid, we wanna make sure that all of our ports are facing the front of the vehicle. And then the tab here, you're gonna see this little flange, we're gonna have one on the other side. We actually went ahead and bent that down. And then we drove four holes into the fuse box lid. We have one here, one here and then two on the side. And then in order to make sure that you don't have any issues with the fuses inside, we actually stuck the bolt head on the inside. We just used a Phillips head screw and then came out the other side and called that up with a flange nut. So that's pretty much how we attached it to the fuse box lid there. You wanna make sure that you use some sort of sealant as well, so water can't get in. So in regards to the vacuum connection here, the installation method is gonna vary depending on what sort of configuration our truck has. So this particular model is a diesel model. So it has hydro boost brakes. Therefore we won't actually be splicing into any vacuum lines. So you're gonna get a hydro boost brakes kit that comes with your actual full kit as well. And it consists of a few different parts. We're gonna have a little cone shaped rubber plug as well as a cap, that kind of looks like a valve stem cap. And we're gonna install that over here on the exhaust port. You just simply place the rubber cone in there and then screw on the cap to tighten it. And then as far as the vacuum side, you're gonna cut a two inch section of your rubber hose. You're gonna slide that off the barbed fitting, and then you're just gonna simply insert the plug. That finishes up for the vacuum connection for models equipped with the hydro boost brakes. So in regards to the wiring for the operating unit we have two wires coming from this. They're both black wires. It doesn't matter which one we hook up to which function, so long as we get the correct function. So one of these is gonna go straight to the ground. So I like to use the battery. I just simply run that black wire over and across, crimp on a ring terminal, attach it straight to the post here. Now yours may or may not have a nut on there already, so we went ahead and just used the nut to secure that ring terminal. And then the other wire from the operating unit, that's gonna tie into one of the wires from your breakaway switch. Again, it doesn't matter which color wire we use on the breakaway switch. So here we have our breakaway switch mounted. It needs to be on the front of the vehicle here. Now what we did to mount ours is, there's gonna be a little plastic underbody panel here that sort of holds the bottom of the license plate in. So what we did is, we actually just drilled straight up through this and into the bumper behind it. There's gonna be a metal support structure a little bit above that. You're gonna have to drill through a couple of layers of plastic, but then you should be able to use a self tapping screw. Or if you wanna drill the hole out entirely, you can use a nut and bolt as well to attach the breakaway switch to the vehicle here. You just wanna make sure it's nice and sturdy. It does need to move a little bit but you obviously don't want too much play. But then the two wires that we have coming from the breakaway switch, we mentioned one of them needs to be hooked up to the operating unit. We're gonna make our connections up in the engine bay. So what you're gonna do is, you're gonna take both of the wires. We're gonna route them over. We actually drilled a hole in this bottom lip of the fascia here because we ran our wiring through there as well, as well as the airline tubing for the airport, but we'll show you that a little later. But basically we just need to find a path to get up behind the engine here, up into the engine bay. So here we have our two wires coming up into the engine bay here. Now yours may be a different color. We actually had to extend ours a little bit, but again one of these needs to be attached to the wire coming from our operating unit. The other one is gonna be ran to the positive battery terminal with a fuse holder in between. But we're also gonna need to T into this, another wire. We used the brown wire that comes in our kit. That's actually gonna be ran inside the cab of the vehicle. So again, just to recap, one of the wires coming from the breakaway switch, goes to the operating unit. The other one goes to power with a fuse holder, and then another wire which you can kind of see here, our brown wire, we ran that up and into the cab of the vehicle. So now we're gonna have two final connections here, on the operating unit that is. We have the air in and the air out. So the air in is gonna go to a plug and a bracket. We showed you that a little earlier. But that's gonna go on the front of the vehicle, so we need to take our airline tubing, cut a section off, route it down, into the front of the vehicle. And we'll show you that connector now. So here we have our little quick disconnect here that gets mounted on the front of the vehicle. Now this is what we're gonna hook the coil hose up to, to bridge the gap between the motor home. Transfer the air over to the towed vehicle. So it's pretty simple to install. We just have a two hole bracket. We again took some self tapping screws, drilled through that first couple plastic layers and then into the metal up on above there. So once we have it secured though, we're gonna have a push-to-connect fitting on the back. We're just gonna simply cut off our excess line. Make sure we get a nice, straight, clean cut and then just push it into the connector there, 'till it locks in place. But that's pretty much it. They're very simple. So then finally, we have our air out connection on the operating unit. So we took what the remaining air tube we had was, we ran over here on the inside of the fender, and then along with that brown wire that we used earlier, we poked that through this grommet and ran inside to the vehicle. So I will tell you guys, this grommet is pretty stout. There's actually a couple of different layers and it's pretty hard to get your airline tubing in your wire through there. So what you're gonna need to do is, we went on the inside and we just sort of shoved a metal screwdriver through there, preferably a Phillips. And then we came out the outside of this grommet here, we attached our airline to the end of that screwdriver by pressing it on. And then with two people, we pushed on the airline and pulled on the screwdriver to get the airline tubing through there. Now honestly, this is probably the hardest part of the install, just 'cause that grommet is so stout. So just be patient, give yourself some time to get your wiring, your airline tubing through there, and you should be fine. So to finish up the vehicle side of our installation, we're gonna have a monitor light that has a sticky backing to it. We're gonna attach that to the rear view mirror here. And then we're gonna have a coiled wire here, rather a jacket, two wires here in this little outer sleeve. We're gonna run that up over in the headliner, just tuck it back through there, down the A pillar. And then there's gonna be some other dash panels between the A pillar. We'll tuck that through. And then the wire came back here, through the weather ceiling and then we'll just drape it below here. So once we have our wire routed all the way down through here, we're just gonna leave it dangling in this area here because we have a couple of connections we need to make. So we're gonna leave our wires dangling for the monitor light, and we're gonna go ahead and hook up the actuator now. So what you're gonna have to do is, there's gonna be sort of a foam padding with a small, soft, plastic layer on the front. We're gonna need to make a little cut out there, right where you can see, we have our metal bracket. Normally that would be bare metal. We'd have that piece of foam there. So you're just gonna take a razor knife and make it a little cut out there. So you have room to work. But once we have that out, directly above that stud on the firewall there is where we're gonna mount our three holed bracket. So we have some long self tapping screws in our kit here. We're gonna attach that on the outside of each one and secure it to the firewall. In the center bracket there, we need to make sure that we place our anchor or the center hole on our bracket, we need to make sure that we place our anchor over the self tapping screw before we attach it. But then we can move on to the actuator which gets attached to the brake pedal arm. So that's what the actuator looks like. We're gonna need a 3/8 inch socket to remove those nuts on the bracket. And then we're gonna place it over the brake pedal arm. So we have the actuator on the right side of the brake pedal arm. So that's what's gonna work best for our setup. There's a little bit of fine tuning you have to do, adjusting the anchor point and the bracket location here on the brake pedal. But we wanna make sure that we get the actuator up on the brake pedal arm, as high as we can. So then we're gonna loosely attach our bracket there just wrap it around, like so. We're gonna need to make some fine adjustments because essentially, what we need to make sure of is the angle of that cable, is not too great in either direction. It needs to be relatively straight while we depress the brake pedal. So we can go ahead and test that now by holding the actuator and then pressing the brake pedal. We just wanna pay attention to the angle of our cable, coming off that actuator. If it's too sharp, it can wear the cable over time and cause it to break. So you wanna make sure that you're within a certain degree of margin. There's a pretty good instruction in the manual that shows what degree you need to be within. So to finish up our actuator, we're gonna go ahead and connect the airline tubing that we ran into the vehicle earlier. We're just gonna have a push-to-connect fitting at the top of the actuator. You just wanna cut off your excess line, make sure it's a clean cut and just push it into the connector on the top of the air connector. And that's gonna be what transfers air from the operating unit to the cylinder. But then you're gonna have the reed switch on the actual cylinder. We need to go ahead and wire that up with the indicator light and the power wire that we ran inside the vehicle earlier. So the way this all connects is, most of our wires are hidden now but it's pretty self-explanatory, it's pretty easy to hook up. There's not too many connections. So with the indicator light, there's gonna be a black wire and a red wire. The black wire is the ground. You're gonna need to take a self-tapping screw along with the ring terminal and ground that to a bare metal surface here, inside the vehicle. We found a nice open spot directly behind that kick panel there, around where the emergency brake cable is. But then the red wire, we'll attach that directly to the blue wire coming from the reed switch. Which is the two wires that come from the actuator. And then the other wire from the read switch, is a violet wire. We're gonna simply hook that up to the brown wire that we ran inside the vehicle earlier, which is tied into the battery and the breakaway switch. But that's pretty much it. We just tucked the excess wires. We zip tied some of them, the ones that we're up, on above the dash, under the dash here, rather. And then we just tucked them behind that kick panel there. So to finish up our installation, you need to jump on over to our motor home here. We have a few things you need to install. The first thing we're gonna install is the air tank assembly. So here's what the air tank assembly looks like installed. Now, a lot of this is gonna be based on what motor home we have. So much of this is just gonna be sort of an overview or guide, to help you guys install it at home. In regards to specific lines that we're gonna be slicing into, specific install locations, these are obviously gonna vary by application. But here's where we have our coach tank mounted. So granted, we need to make sure that we're close to our relay valves 'cause we're gonna be splicing in to both the supply and the metered airlines. So there's gonna be a two hole flange on the back of the tank there. We'll simply just drill two holes and attach it to some sort of metal support structure with the provided hardware. So now that we have the tank mounted, we're gonna go ahead and start making our connections. The first connection we're gonna make, is to the supply line. So the supply line, runs between the relay valve block and the air tank. The line should be a 5/8 inch diameter and it should be green in color. So here's what our relay block looks like. Now, granted, yours may look a little bit different, depending on your specific application, but if you follow that large green line between the air tank, you should be able to find the relay block which is what we have here. Now, before we splice into this, we need to make sure that we release all the air from the motor homes tank there. So you wanna hop in your motor home there and start pressing the brakes, until they're empty. But once we've did this, we can go ahead and cut that line. Now we need to make sure that we don't cut it, on anywhere where there's too sharp a bend. We want it to be as reasonably straight as possible. Then we can go ahead and sever that connection. We can simply place one of our T's in line with that. And then run the other side, the output side of the T, we're gonna use a piece of airline tubing and we're gonna run that to the correct port on our tank, which will be labeled. So the next thing we're gonna do, is find our metered air connection. So our metered air connection is a little bit more difficult to find. And again, please verify all this beforehand because it does vary by chassis and even within those chassis's. So ours is actually this orange line that we can see here. A good way to test this is, is to actually undo the line and then have someone go in the motor home and hit the brakes, and you should feel pulses of air on this line. If you do, you know you've correctly identified the metered air. So it should actually be ran to the same relay valve block, as we spliced in the supply line from. But once we find this we're gonna use one of these smaller T fittings that come in our kit there. We'll simply cut that line, in a straight section of there, place one end in each of the T's, and then finally the output side is gonna be a little bit of a smaller line, and we're gonna run that to the tank to the respective port. So now finally, if we come back to our air tank here we should have one final connection. It'll be on the same side as our metered air connection. And basically, we're just gonna take our leftover airline tubing, we're gonna run it from that push-to-connect port and then all the way back to the rear of our motor home here, to an L shaped bracket that we have in our kit. So here you can see, we have our air check here, mounted on the rear of our motor home. Now granted, your bracket probably looks a little bit different than the one we have mounted here 'cause this is actually a factory one. But the connection at the rear, is just gonna be a push to connect, like we've been using so far. So it's pretty simple. Just go ahead and mount up your bracket there, plug in your airline to the rear and that'll conclude our installation. So now we're gonna go ahead and take our coiled air tube here. We're gonna hook it up between the motor home and the towed vehicle, so we can test the braking system. And that's gonna do it today for our look-in installation of the Demco Air Force One supplemental braking system, here on the 2015 GMC Sierra 2,500..


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