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Roadmaster Brake-Lite Relay Kit Installation - 2018 Ford F-150

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How to Install the Roadmaster Brake-Lite Relay Kit on a 2018 Ford F-150


Speaker 1: Today on our 2018 Ford F150, we're going to be taking a look at and showing you how to install the Roadmaster Brake-Lite relay kit for towed vehicles, part number RM-88400. First let's talk about what comes in our kit. You're going to have your brake relay, which is going to attach to your brake light switch, your fuse tap, your 10 amp fuse, a few butt connectors, ring terminal, your self tapping screw, and a little extra wire.So let's talk about what our vehicle's going to do if we don't have our brake relay installed. Let's say you have a brake system on your towed vehicle or on your Ford. You're towing it down the road, when you hit your brakes in your RV, the brake lights are going to come on in your truck or in your towed vehicle. However, when you hit your brakes and you turn on your blinker in your RV, you're only going to see the brake lights in the truck because the brake light signal is overriding that turn signal.

What this relay is going to do, it's going to allow that signal to transfer from the RV to the truck. When the key's in the on position, that circuit will close to allow you to use all the proper functions in the truck by their self. When the key is turned off, that's going to allow the signal from the RV, your blinkers, and your brakes to function properly in your towed vehicle.Now if you have a push button start, you'll use the blue wire. If you have a key ignition, you'll use the green wire. So what we're going to do is we're going to eliminate our blue wire.

We'll just cut that off. Your black wire's going to run to your brake light signal. Red wire's going to run out to your fuse. Green wire is going to run to your brake light switch and your white wire is going to be the ground. So if you have a turn key ignition, you're going to use section A of your instructions.

If you have a push button start, you're going to use section B of your instructions.Couple of things you're going to need. This wire, red wire is not going to be long enough to get to your fuse because it's all the way in the passenger side of the engine compartment. So you're going to need to pick about six foot of wire and you can find that on our website using part number 16-1-1. Another thing you're going to need, is you're going to need a volt meter. And that's to test your wire from your brake switch.Let's talk about why you need a volt meter over just a regular test light.

You're going to have multiple wires going into your brake light switch. If you test those wires, you're going to have several of them that are going to make that light, light up. However, you're not going to know which one you need to tap into. The brake light switch or wire that you're going to be tapping into, is the only wire that's going to read 12 volts. All the other ones will not.Another thing I like to have is maybe an extra ring terminal, a little bit larger. Just in case we find a stud on the firewall or somewhere that we can tie into that we don't have to actually bolt in or screw into the metal itself. So what we need to do is on our driver's side, we need to take this panel off. All we're going to do is pull back on it. It's going to be attached by a few clips. Just like that, we'll fold it down. If you look right here, you're going to have a couple wiring harnesses. We need to unplug those and we're going to take them and we're going to tuck them right up here out of the way for now. So next we're going take a 10 millimeter socket. We're going to take out these two screws and a bolt. Then we're going to take out the top two on this metal panel.Remove that panel. And then right on the back side, you're going to have two push clips that hold this in place. And we're just going to push them together and slide them out. Then we're going to take this panel, set it aside. So we're looking for this light blue switch right here. The wires that are coming off the back of it, we need to take this coating off or this tape. So we'll just start peeling it off. You want to peel it back pretty far. Then what we need to do is test our wires to figure out which one is going to give us that 12 volt power when the brakes are applied. We should only have one. We'll start with the one all the way on the left. With an extra set of hands, we'll have somebody push on the brake pedal. And I think that's going to be our wire, 12.14 volts. So it's going to be our purple wire with the white stripe.Next thing we need to do before we do any splicing on that wire, is we need to come over to our passenger side kick panel. There's a panel right down here. We're going to remove that panel. And you're going to see the fuse panel in here. What we need to do is, we need to take out the brake light fuse. The reason we're going this is we don't a malfunction with the wiring. If you get a malfunction with the wiring, you're going to have to take it into the dealership to get fixed and it may not be covered under your warranty. So you want to make sure you pull this fuse before you do any cutting on your brake light switch. Now what you're looking for is this 10 amp fuse right here in spot number 15.If you look at your owner's manual, it's going to say your brake light fuse is in spot 14. This fuse right here has three prongs on it. So it's working three different functions. This is actually going to be spot 14, this is going to be 15. So it's going to be this whole fuse we're going to be taking out. We can just pull that out with some needle nose pliers. So now we're going to cut our purple wire. You want to make sure you cut it back from the switch a little bit. And then we're going to make sure we strip back a little extra on each side because we're going to double it over to make sure we get a good hold on our butt connectors. We'll add one of our blue butt connectors on this end. Give it a little tug, make sure it's got a good hold and we're going to do the same thing on the other side.Then we'll add one of our blue butt connectors on that end. Make sure you good connection. So now we'll take our green wire and it's already pre-stripped. It's just a little bit too long. So cut some of that off. And our green wire is going to go on the wire that's coming out of our switch. Put that in the end of our butt connector, crimp it into place. Then our black wire is going to go into the other end of our wire that's going out to our brake lights. Crimp that on. Next thing I'm going to do, is I'm going to put on my relay. I'm going to find a place to attach it. Now right up here there's some existing wiring. I'm going to zip tie it right to that line.I'm going to cut off our excess from our zip tie. Now the reason I want to do that first, is so we can make sure we have enough room for our ground wire. Now if you look right up here, we have a large stud. We're going to take the large ring terminal that we picked up. Put it on our white wire. Crimp it into place. Make sure it's got a good hold. Then we'll take the 13 millimeter socket and we'll remove that nut. Place the ring terminal with our ground wire on it and replace the nut. So we've taken our extra red wire and there's a rubber grommet right here on the firewall. It goes out to the engine compartment. Now we put a hole in the rubber grommet. You can do it with a very small flathead screwdriver, Phillips screwdriver poke a hole in there. And then attach this to the wire to a wire hanger, airline tube if you have some works well to get it through the hole.So anyway, we're going to take our red wire from our switch then we're going to put it on the red wire here, which is going to go to our fuse panel over on our passenger side in our engine compartment. Put one of our butt connectors on. Then take our red wire, coming from our engine compartment. Then I'll put it on the other end. We'll take all of our wires. We'll just kind of bundle them up. I'm going to zip tie them right here to this existing wiring, just to keep them up out of the way of whoever's driving the vehicle. Then we can put our panels back in place.Now our red wire coming out of our rubber grommet in our firewall, pull it up, ran it right across the back of the firewall. I tucked it in behind that cardboard panel right over to this side and went underneath of this, right to my fuse panel. Now what we have determined is from 17 to 18, fuse panels have changed. And the fuses have changed. They went to the micro fuses. So, that being said this fuse tap that comes in your kit will not work. The fuses are too small, these will not fit down inside of the holes. So you're going to need a little fuse tap like this that'll slide over one of the pegs. This you can find at a hardware store. You're also going to need a mini fuse holder, part number SWC9545.So now we have to find an ignition source. So on one of our fuses, what we're going to do is you need to test. You take a test light and hook it up to a negative power source. And you're going to touch just the top edge of the prongs on the top of the fuse. Whichever one comes on with the power or ignition off, you're not going to use. You want to find one that when you touch it, it doesn't come on at all. When you turn the key on, it comes on. That's going to give you an ignition power source. Now we need to cut our wire to length. So we'll cut down our red wire. We need to strip back our fuse holder. Strip back our red wire, be ran from the inside of the vehicle. We're going to add on a heat shrink butt connector because it's going to be living out side of the vehicle, maybe exposed to some of the elements. We'll add our fuse holder, butt connector onto our red wire going inside the vehicle.Next we need a spade connector. You want to make sure the spade connector's going to fit on the end of your tap. We're going to add that onto the end of our fuse holder. Then we're going to heat it up, just shrink it down. I went between this 25 amp and this 20 amp fuse right here. Now when you test it, one side's going to be powered and the other side is not. So you want to make sure when you stick this in, you stick it in on the hot side or the powered side. So when we test it, this side was our powered side when the ignition was on. So we're going to put that back on that side. So now I'll connect my fuse holder with my spade connector onto my fuse. I want to make sure that my second 10 amp fuse that comes with my kit, I'm not going to put it in my fuse holder til I make the connection.Now the reason we're doing that is we don't want any back feed. We want a direct connection, because we don't want to mess up any of our factory wiring. So now we'll put in our 10 amp fuse. We can reinstall our cover. Just like that. Last thing we got to do, is reinstall our fuse to our brake light switch.So now we're going to test out our brake light switch relay. We're going to simulate hooking up to our RV. We're going to turn on our left turn signal. Now what we're looking for is, we're looking for our left turn signal and then our braking system that's going to be in our vehicle to apply the brakes and that brake light not to override our turn signal. Brakes on, brakes off. Brakes on, brakes off. As you can see, our turn signal is still on, which is saying that our relay is working correctly. And that'll do it for a look at and installation on the Roadmaster Brake-Lite relay kit for towed vehicles, part number RM-88400 on our 2018 Ford F150.


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