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Roadmaster Universal Diode Wiring Kit Installation - 2013 GMC Terrain

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How to Install the Roadmaster Universal Diode Wiring Kit on a 2013 GMC Terrain


Hi there, Terrain owners. Today, on your 2013 GMC Terrain, we're gonna be taking a look at and showing you how to install Roadmaster's diode wiring kit. Quick brief overview of all the components we've got here, 'cause there are five main components you'll need when flat towing your vehicle behind your motor home. You'll need your tow bar, which is the connection between your motor home and your vehicle; your safety cables, which is a supplementary connection in addition to your tow bar; your base plate, which is the connection on your vehicle for your tow bar and safety cables to attach to; your diode wiring, which takes all the lighting signals from your motor home and transfer them to the lights at the back of your vehicle, so people know your intentions when going down the road; and lastly, your supplemental braking system, which will apply the brakes in your vehicle when you hit them in your motor home to help you have a nice, smooth braking operation. And this is what you'll see once you have your diode wiring installed. All the components are hidden completely behind the taillight assembly here, and wires are routed throughout the vehicle to take all the lighting signals from your motor home and transfer 'em to the lights here at the back of your vehicle.

I've got the left turn signal on, on the motor home now. We can see the lights mimicking there on the motor home and on our vehicle, and that's it. This will give us all those signals from the motor home, which includes our left turn signal, right turn signal, tail lamps, and brake lamps, keep it as DOT-compliant in all states. Diode wiring is my personal favorite way to get all these lighting signals here at the back of your vehicle versus some of the other options out there. Some other ones are a magnetic light kit where rather than installing the diodes on your vehicle, you just have some lights and have a magnetic base that you can set up on your roof, and then you just route the wire up to the front and plug it in.

Those are all right. It's a quick and easy solution. But the magnetic bases, they have a pad on the bottom to help protect against scratches and abrasions. That pad can eventually wear out, and you can, you know, eventually lead to wear marks on the roof. There's the chance of 'em getting lost.

There's the setup that I really don't like. With diodes, it's a one-time install, and then you just plug 'em in. With the magnetic lights, you gotta get 'em out every single time, you know, and route 'em up, get a little tedious. Another option is a bulb and socket. That's another permanent installed option, kinda like our diodes.

But with bulb and socket, you actually have to drill a hole into the taillight assembly and add an additional bulb. I don't personally like this one because that just leads for a moisture intrusion to potentially occur in the future. You do seal it up and you put it in there, but it's just, it's never gonna be the same as it was when it's from the factory. Also, with a lot of these newer vehicles here, they have LED assemblies that just don't have the room inside for bulb and socket. So it can be kind of a toss-up when you're thinking, "Hey, is this even gonna fit" Let's just rule that out and go with a diode set 'cause we know that, that's gonna work. Our diode set here takes all those signals from the motor home and sends 'em to the lights. It acts as a one-way check valve that ensures that current is only flowing from the motor home to illuminate the light but not able to back-feed into anything on our vehicle here to damage any of its electrical equipment. So now that we've covered some of the features of our diode wiring, why don't you follow along with me in the shop, and we'll show you how to get it installed. We'll begin our installation here at the back of the vehicle with our lift gate open. We're gonna remove both the driver and passenger side taillight assemblies. To remove them, we're gonna remove the caps that's holding or covering up the fasteners that's holding it in place. So we're just taking our screwdriver in the little notch. There's kind of a little notch there at the bottom. And we're just prying that out and pulling it out like that. We'll do the same thing with this one, right in the little match here at the bottom and pull that out. We can then remove the two bolts behind it with a 10-millimeter socket. And then, after we remove both of those, the whole assembly here is gonna pull straight towards the rear. But when you do this, I highly recommend using a trim panel tool like this and coming in kinda the side here. So we're gonna kinda just give this a little bit of a pull. It's usually pretty stuck, and it's just two pins is all it is in there. But a plastic trim panel tool like this is gonna make a big difference on getting the leverage you need behind there to get that to pop out 'cause you can actually damage these fairly easily if you don't pull on it with the right force in the correct direction. Here, you can see those two pins where they fell into the sockets here. Now we've got this pulled out, we'll just disconnect the electrical connector, put our assembly aside, and then we can remove the housing over on the other side. So now, we're gonna be feeding up our wiring and our kit. You'll see you get a bunch of wire here. This kit has a four-pole end on it. There are a bunch of different combinations to this kit, and they all wire and install the same way, but some them have different ends. Most of the kits come with bare wire where there's no end on it, and we're actually not gonna use this four-pole, and so we'll be cutting it off. But we need to feed it up in here. And that's part of the reason why we're gonna cut it off, it's a lot harder to feed that big old end up in here. Gonna need just the wires, and all we need is the wire. So we're just poking our wire down in here, and you can see the ground down below, so just kinda poke it down in there, and then you should be able to reach around the other side here. Find your air line hose. There we go. Pull it out the other side. Once we get it down here, we're gonna cut this end off now and attach it to this to pull it up. So now we got our fish wire down here, we're gonna get rid of this four-pole end. Unless you guys really need the four-pole for your flat tow, you can leave that on there. But in most cases, you're not gonna need this, and you'll be changing it to a different style of connector for your flat tow setup. So we're just gonna trim this off of here. I like to trim it after the point where kinda like right where they're all split here. Saves us a little bit of time because we need to, we'll need to separate each one of these wires. But for now, we are gonna peel back just the green wire. We don't need to peel back super far, that's probably good enough right there. Just enough to when we pull this up, we can reach up below and be able to grab our green wire 'cause that's gonna go over to the passenger side. We'll then just take this wire now, and we're gonna tape it to this harness, and then we're just gonna pull our wire up. And there we go, it comes right out the other side. Here, we can detach it and then start making our connections. So the first thing I like to do when I get this up here is kinda get those three separated. Our green one is still down there. We can pull it, and then I like to zip tie this wire to this factory harness here. This way, that work we just did of feeding this wire up here can't accidentally fall back down in there. So we'll zip tie that right to there. And that'll just make it a lot easier to work with now. So the next thing we're gonna do is we're gonna cut back this and start hooking our wires to our diodes and stuff. We'll first start right here since we've got these ones separated. We'll make these connections here. So you can go ahead and strip these back. The yellow wire is gonna be our motor home left turn and stop signal. Our brown is our taillight signal. And the white wire is actually ground, but we're gonna be using a little bit of this white wire here in our harness to make a jumper from our taillight circuit that's on this side, the brown wire, over to the other side 'cause we need our taillights to run on both sides, and the brown circuit is the only circuit that will turn those lights on. So we can just do that with a jumper. So we're just taking these two now, twisting these two together. And this will attach to the yellow spade terminal in your kit. When you get your diodes for a spade terminal, they're usually just pushed on the diodes. You can just pull 'em right off. It's just the spade end that's pressed on there. The single yellow connector has a larger diameter on the inside, which allows it to accept two wires. All the other ones in your kit are gonna be a blue spade terminal, and they're designed to only accept a single wire. So now, we're just gonna crimp this down, and if you need a set of crimpers, you can get some here at etrailer from Performance Tools. It's what we're using today. There we go. Next, blue spade terminal for this side. All right, so we've got these wires prepared. Next, we're gonna peel back the sheathing and electrical tape that's on here, so we can connect to the factory wires that are in here. The main wires we're concerned with are pins one and two here on our connector. Pin one is this yellow wire with the black stripe. That's gonna be our stop and turn signal circuit, the one that our yellow wire is gonna wanna mate up with. And the brown wire that's located here in the pin two slot is our taillight circuit, and our brown wire here with our little white jumper wants to mate up with that one. So I'm gonna go ahead and get these sliced back, get our wires exposed, get 'em peeled back. Be very careful when you're cutting this. We don't wanna nick any of the existing wires that are in here. Once we get this peeled back, we're gonna find a spot in the middle here. We'll trim these two and we're gonna put blue spade terminals on them as well. We'll now take our diodes and start hooking 'em up. I've got all the spade terminals crimped on the wires that we just talked about. So the yellow is our stop turn for the factory wires as well here. So we're gonna plug our diode here with the outside there, arrow and labeled out, all these is gonna go to our connector side. So we're gonna start with our yellow circuit. Plug the out into that, that's our stop and turn circuit. We need to reconnect our diodes back together, so we're gonna plug in the yellow that's going towards the rest of our vehicle here into the in. And then, we can take our other yellow wire here and connect it to the other side of the in. We'll now take our other diode, and it's gonna hook up basically the exact same way. I'm gonna use this for the brown circuit, which is our taillight circuit. Out always goes towards the connector side, towards our light bulbs. And then, we need to reconnect the factory circuit. So I'll go to the in connection on the other side, and then we've got our brown wire from the motor home as well as that white jumper wire that's gonna take these signals over to the other side. Get those plugged into the other side of the in here on this diode. And these can be pretty tight. They put the terminals very close together on these. So they are very tight when you go to put 'em on there, especially that yellow one there. All right, so now that we've got these on here, I'm gonna throw one more zip tie on it just to kinda hold everything together here. And before I slip that zip tie on there, I'm gonna peel the adhesive backing off the diodes and just stick the two together. You can stick these back here behind the assembly, but you oftentimes don't have enough factory wiring. You have to extend them and stuff to be able to do that. You stick 'em together, that'll keep them from clunking around, and then we can throw a zip tie around everything here to kinda hold it all together. And this should work out plenty fine for us here. So next, we're gonna be hooking up the passenger side. It's gonna be basically the same connections here. It's very similar. We're actually gonna be using the same pins over on that side. They are different wire colors. Pin two is still gonna be brown, but pin one over there is gonna be a green circuit. We're gonna take the green wire that we had left down below, and we are actually gonna run that over to the passenger side and then up. And what I usually like to do with it is I'll kinda hold it over, kinda hold it up. And after I feel like I've got enough of that green wire peeled back for this side over here, I'll then take that green wire and I'll fold it back down the excess wire I got. And when that green wire ends, that's where I'll cut the white wire. So that way, I know that I've got an equal length of green and white wire to run from that side over to this side. So we'll get the side removed here, and we'll get the side put together. So here we are over on the passenger side. Now, you can see that we've made the connections exactly like we talked about there. So there's our factory connector. You can see pin two still brown. Pin one does change to a white wire with the green stripe. Those go to the outs. After we had cut those circuits, they go to the ins of the respective colors. So green and white, it's gonna go back to the green and white. Brown is gonna go back to brown. The white wire that we talked about for our jumper plugs into the other in for the brown. You get that taillight circuit jumper to this side. And then, the green wire, which is the passenger or right turn signal and stop light circuit from our motor home, that's gonna plug right into here because the green wire with the white stripe is your factory stop turn circuit. So we've got both the driver and passenger side assemblies, all dioded up here. At this point, we need to route our wire from underneath up to the front, and while I'm down there, I'm also gonna show you the path I took to get the green and white wire routed over to the other side. We just kinda stuck behind the bumper here. So slide these back together, and then we'll head underneath. You do kinda gotta pay attention when sliding your diodes back together like this. Make sure that they're gonna fit inside the assembly there behind it and not obstruct anything. Just kinda taking a peek at it before you slide it in. And then, it just snaps back into place, and you can reinstall your fasteners. So here we are at the back of the vehicle. We're underneath here on the driver side. This is where our wire came down, and this is where we passed it over to go towards the passenger side. So here, you can see that single green wire where we had originally kinda snipped that off. And then, this is that excess white wire that we folded back and extended over. The rest of our wire goes back that way. It's gonna head towards the front of the vehicle, but our green and that white extension we made just runs right over here, and then it goes right up underneath the passenger side taillight assembly there. From there, the rest of that wire that goes back needs to head towards the front of the vehicle. So we've got all of our wires here. It does look like it's missing the white wire here because it is, but we're gonna meet back up with that white wire here at a later point. When we head down along the frame here, there's a factory wire harness, it's right here on the inside of the frame. We zip tie it to that factory harness. And we did that at multiple spots right here in this location, 'cause there's a lot of suspension components here that move up and down. And there's really not a lot of things to actually protect the wiring. So that factory harness there is routed in a very special way that keeps it safe, so just follow that exactly with your wires. Once they come out here on the other side, kind of right above the suspension here, we can run along our fuel tank. And here, we can be a lot more relaxed. The suspension components aren't in our way. We can just continue following our brake lines up. I zip tied along the way to the brackets here. I don't attach to the line but to the bracket. And then, we do that all the way till we get to about here. At this point here, we had our fish wire that we ran up from our engine compartment, we taped our wire to it. We're gonna be pulling it back up because our supplemental braking system requires signals from our motor home and its diode wiring, so we're gonna have to tap into this. That's why we're going up to the engine compartment. If your braking system doesn't require that, you could just head all the way to the front. But most of your braking systems are gonna require this, so if you're unsure, I would just route it up to the engine compartment first, and then forward to easily access those at a later time. Now, before we head up to pull our wire up, we talked about that white wire, our ground wire. And that ended up being about right here, about right at the back of the fuel tank, right in front of the tire. That's kinda where the wire ended up for the length that we had left here from what we've used before. So we're gonna strip this back. And then, you get a ring terminal included in your kit. Get that ring terminal out of there. And it's a small ring terminal because this is just for our ground for our diodes. So I gave it a little bit of a twist. That just makes it easier to get the wires to poke into our ring terminal here. And then, we're just gonna crimp this into place. Poking that in there and crimping it down. All right. Now that we've got that prepared, we're gonna feed this down a little bit here towards the front of the vehicle. And right here looks like a pretty nice spot to put our wire. It's kinda down where it should be easy enough for us to get our tools in there, but up high enough to where it's not gonna drag on the ground or anything like that. So we're gonna take the screw that comes in the kit as well, slide it through our ring terminal, and then we're just gonna run it right into place here. And don't go too crazy with it. See how the wire still rotates there So we need to tighten it just a little bit more. There we go, that feels good. Nice, secure connection. So we're now back up top again. We're grabbing our fish wire here, and we're just gonna use this to pull that wire all the way up. There we go. Get that pulled up there like that. So after we get that wire pulled up, I zip tied it to the factory harness across the back here to ensure that it can't drop back down, and it stays tucked up against the firewall, away from any moving parts. From there, we just routed it here. Just kinda following by this AC line hose next to the battery here. And we zip tied it to a factory harness right there. And then from there, we just go straight down, and then it pops out right here, just on the inside here of the driver side headlight. And then, we can just kinda follow this factory harness over, probably put a zip tie on it right here to hold it onto that factory harness, just to make things nice, neat, and clean. And then, it routes over to where our mounting location is on our base plate. We're gonna be adding the six-pole connector here and wiring it to it, but we're gonna wait until we get our fascia back on 'cause we're likely gonna have to trim out areas on that fascia to make the connector fit. And then, we'll get that wired up. So once we get that fascia on, we'll show you where the appropriate pins go in the connector. So we've gone ahead and got our fascia back installed now. We just pulled our wires right through here. You can reach in the opening pretty easily, so just pull those through after you get the fascia on. This is for our braking system. So we're just gonna set this off to the side. It's for our monitor light. We've got a InvisiBrake system from Roadmaster. You might have one of those as well, but that's not gonna go in our connector. So here's what we have left of our wires. And this is our four-pole connector here that we're going to attach to. Got more wire here than we really need, so we're gonna trim off some. I do always like to leave a little excess just so we can always pull this out and check it and, you know, do some tests or make it easier for adding additional accessories in the future. So we'll leave just a little bit there, and then we'll cut the rest of this off. And then, we can take each of these wires and separate 'em. So we're just gonna snip right in between each one. And now, we can give that a little bit of a peel backwards. Now, take the boot off of your connector. Slide the boot on your wires, and just tuck that right up in there for now. And then, strip each one of these back. And we don't wanna strip too much. Something like that's probably pretty good, 'cause the cavities on these connectors isn't very deep, and any loose strands could potentially cause shorts on your other circuits, which can give you some pretty strange functionality sometimes. After we've got each one stripped, we're just gonna twist them. Just helps keep the strands together, makes it a little easier pushing them inside of our connector here. After we get each one of these twisted, we'll grab our connector next and a Phillips screwdriver, and we're gonna start loosening up the terminals for the circuits that we need. And I always like to start with ground, which is our white wire here, and they're labeled on the backside of our connector here. So let's find that ground. That's the one labeled GD on the connector there, it says GD. So we're just gonna loosen this one up, and then we're just gonna work our way around. So if we go to the next one to our right here, that's LT for left turn, that's our yellow wire. So we want that one. Move again, that's RT, which is right turn, that's our green wire. So we'll take that one loose. Next, it's labeled S. That one we're not gonna use, so we're gonna leave that alone. Next is TM and that is for our taillight circuit, that's our brown wire. So we'll open that one up. And we're back full circle. The center pin here is often used for our accessories, such as a charge line circuit. We don't have one of those, so we're not gonna be using it. So you get a couple extra slots here for additional accessories in the future if you wanted to add 'em. Now, we're just gonna take each wire and poke it in the appropriate spot. If you need to, you can pull back a little bit more from each one to make it a little bit easier. And again, I always like to start with ground, so I'm gonna find that GD, which is right there. Slide the white wire in, tighten down the screw, and we're just gonna move on to the next terminal just like we did before loosening 'em up and poking in the wires. So now we've got 'em all attached and screwed down, we want to seal this up. So we're gonna use some dielectric grease here on the inside that's gonna help keep out moisture and therefore keeping corrosion out of it. We're gonna be fairly generous with this 'cause we're getting towards the end of this here. After we thoroughly coat it, we'll slide our dust boot down over the end. And then, I always like to take electrical tape and put it over the dust boot. That helps keep the dust boot from sliding off, and it can just help further keep that grease trapped inside of there. And included in your kit, you do get a little bit of wire loom. We went ahead and put that on there and taped that on there as well. That'll help just protect it a little bit, and it makes it look a lot nicer. We'll now mount it up to our attachment here. This is laid down to our base plate. The hardware here that we're gonna use came included with the base plate. Now, if you have a different manufacturer's base plate that doesn't provide a mounting location for your electrical connectors, we do have no-drill brackets and six-pole brackets available here at etrailer, so you can make your own solution. Now, I just take our eight-millimeter socket and run 'em into place. Now that we've got that securely mounted, we can test it out. You can put this into the back of your motor home. We're gonna grab our test box, and make sure everything's working properly. So I've gone ahead and plugged in my test box here. We wanna make sure we have all the necessary lighting signals, which includes our left turn signal, right turn signal, tail lamps, and brake lamps. With all of our systems working properly, we're ready to hook up and hit the road. And that completes our installation of Roadmaster's diode wiring kit on our 2013 GMC Terrain..


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