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Roadmaster Smart Diode Wiring Kit Installation - 2020 Chevrolet Sonic

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How to Install the Roadmaster Smart Diode Wiring Kit on a 2020 Chevrolet Sonic


Hi there, Chevy owners. Today, on your 2020 Chevrolet Sonic, we're gonna be taking a look at and showing you how to install Roadmaster's smart diode wiring kit for incandescent bulbs. There's five main components you're gonna need when flat towing your vehicle behind your motor home. You're going to need your tow bar, your base plate, your diode wiring, your safety cables, and your supplemental braking system. So here, you can see the lights on our Chevy Sonic are mimicking that of our motor home. And that's the main purpose of our diode wiring kit is to take all the lighting signals from our motor home and transfer them to the lights here at the back of our vehicle.

This way, when we're flat towing, we can use the existing lights on the vehicle to provide all the necessary lighting signals. This is my preferred method to getting lighting signals on your vehicle because it's just the most integrated, so it's the easiest to use once you've got it installed. It is a little bit more of an initial installation than some of the other options, but once you're done, it is by far the easiest to use for the rest of your flat towing experience with it. The diode wires are going to route from the front at a connector that'll plug into your motor home here to the back. And our diodes will be placed behind the taillight assembly.

They will splice into the existing wiring, and the diode actually is a one-way check valve to allow the signals from the motor home to go in to illuminate our bulb, but they can't go back down the wiring in our vehicle and cause any damage to the components on the vehicle. Our vehicle wiring still stays intact and passes through the diode as well on its own dedicated portion of the diode that will allow the vehicle to still function as normal as well, and it also cannot backfeed up to the motor home. So this is definitely my preferred method. You do have to splice into your wiring, and some people at home might go, "Hey, maybe that could affect my warranty on my vehicle," so there is another option. Some of the other options you have are a bulb and socket.

That's my least favorite option. That option, you would physically drill a hole into your taillight assembly behind it and add an additional bulb. That's gonna give you some issues with warranty as well, potentially, 'cause you're making modifications to the vehicle. There's a high chance for leaks to occur into your taillight assembly, which could get you in trouble with safety inspections in some states. So I don't prefer that method.

I definitely prefer this one over it 'cause we don't have to modify the housing. We're just tapping into wiring. The other option where you don't have to do any tapping in is a magnetic light option where those will just simply stick onto the back of your vehicle. The issue with those is every time you wanna use it, you gotta pull 'em outta your vehicle, you gotta stick 'em in place. And then, you have to route the wires up to the front, make sure that they're secure, they're not gonna fall off in any way, and then connect to your vehicle. With our diode wiring, we've got that all hidden inside the vehicle, and there's a connector at the front. And we get all of our signals back here, which includes our left turn, right turn, tail lamps, and brake lamps. And we currently got the hazard lights running right now. Those also mimic just like they do on our motor home up there. So let's head up to the connector at the front, so you can take a look at how that's gonna plug in. So here, we have our connection at the front. Now, this system from Roadmaster does come in a lot of different options. You can get it just with various different cable ends here, so that way you can match what you're planning on using on your motor home. You can get it in a bare option where it's just the wires up here to the front with no connectors, so you can choose your connector end. That's the one we actually installed today because the customer's got Blue Ox tow bar, base plate. They wanted to stick with Blue Ox components, so they have a Blue Ox wiring and connector here as well. But it is all Roadmaster behind it, kinda making all the magic happen behind the scenes. The other options for kits, you can get it with a Roadmaster four-way connector, a Roadmaster six-way connector. And then, with the six-way connectors like you're seeing here, if it's a Roadmaster one, you do have the option to get it with either a coily cable, a straight cable, or a hybrid cable that has a straight section and a coiled section. And that all just varies depending on the tow bar you have. You wanna use a coiled cable if you have a tow bar with no cable management, like our Blue Ox one we're using here has no way to support our cables or anything like that. So a coiled one's the option we would wanna use with this. But if you're using like a Roadmaster Falcon All Terrain that has channels to support your cables, you would wanna use a straight cable with that. And in some cases, if you have a lot of extensions here, like this guy's got a bike rack and stuff on here that extends the tow bar back a little bit, in that case, if you've got a tow bar with channels, you would wanna use the hybrid one so you can run the cables through your channels. But where you've got extensions here, you've got a small section of coiled cable for up here where those extensions are. So I'm just kinda taking a look at all the options that you have here. It just simply plugs in, that's how easy this one is. Once you've done the installation, you just simply plug in, plug in, and you're ready to go. Why don't you follow along with me now in the shop, and we're gonna show you how to get all this installed on your vehicle We'll begin our installation here at the back of the vehicle with your trunk open. That'll reveal the two screws we'll need to remove to get the taillight out. We'll use a Phillips screwdriver to remove the two screws. And what we do on this side, we're also gonna be doing over on the other side 'cause both of these assemblies need to come out, so we can get our diodes installed behind them. Once we get both of these screws removed, we can pop the assembly out of there. It does have some little tabs, kind of in this area up here and down here behind it, so it needs to pull straight rearward to get released from those tabs. So just kinda rock it a little bit, there we go, and that'll pop out of there. So all of our lights that we've got here are just wired directly into the bulb. So you could twist and remove the bulbs from it and get this outta here. But we actually need to tap into the wiring here to install our assemblies. So at this point, we're just gonna stick this guy back here. And then, we're gonna get the other side removed. We're not gonna push it all the way back in, just kinda let it hang out right there. Once you got both assemblies removed, you can take the big harness of wires that come in your kit. We're gonna feed it up under the bottom, back behind our taillight assembly. You might wanna use some kinda pull wire or something to help you do that as well. You can use like a string with some weight tied to it like a nut, and drop it down through an opening. And then, pull it up. Just use some tape to it or something like that. I've already got it pulled up there, so we'll just pull this back. We went ahead and pulled it up right over here. If you look straight down there, if you put a flashlight underneath the vehicle, you'll be able to see light and that way, you know, "Okay, I can see all the way straight down. "That's gonna be the path I wanna route my wires to." Now, on the passenger side here, this is where we routed all of our harnesses up, but you'll notice that you only see the green, the white, and the brown wire up here. The yellow wire, we actually just separated that wire out. These wires just peel back from one another, making it look like a Twizzler. Each one will peel back. Sometimes, you gotta make a small cut with your tool between 'em to get it to start peeling. So just peel the yellow one and just let that one hang down below because we don't need that one on this side. So now, we've got all of our wires pulled up over here. We got the green one, the brown one, and the white one. The brown and the white, we're gonna use a small portion of the white wire to jumper our brown circuit over to the other side. So that's why you'll see here that I've got the white and the brown both attached to a single butt connector. They're just twisted together and connected in there. Our green wire here is our passenger side stop and turn signal that is gonna be coming from our motor home, so we need that over here. The other side will get our yellow wire and then a piece of this white wire here. So now that we've got the wires routed up, we do need to tap into the existing wiring, which is located here. And I just tapped right into the red wire here. So our diode goes in between. And then, we can plug our connections here right in. We're just crimping it right onto the spade terminals that it comes with here. They're all labeled to make it easy. And what we're gonna do here is we're just gonna go over to the driver side over there. I've left that side unfinished. So that way, we can hook it up together. And they're both gonna be the same on both the driver and passenger side. Both sides, you're gonna hook it up the exact same way. You're gonna be tapping into these. The only difference is gonna be you're gonna use yellow wire over on that side. And instead of being a dual wire, we're just gonna have the single white wire that we're coming from this location over there. So we'll show you the way that we routed it after we get 'em hooked up. They just run along the back, they get over to this side, and we'll start hooking 'em up over here. All right, so we are here over now on the driver's side. We routed over the yellow wire. And then, this is the white wire that we're using as a jumper. So this is the small section that's going from this end here. It goes down, it goes across, and it connects in with the brown wire over on the other side. So we're gonna hook 'em up now. We're gonna be sticking the diode in the same location that you saw over there on the other side. So we're gonna cut the red wire here. And you wanna make sure you give yourself enough room to be able to strip it back and make your connections. That looks like a pretty good spot. We'll then strip back each end of our red wire here. And the reason why we're doing the red wire is this is your factory brake light signal, and that's what we wanna use because the brake light signal, can give us both stop tail and turn all using the smart diode. So now that we've got that cut, you can grab your smart diode. We're gonna hook up the car brake out and car brake in. So the in and out are gonna be these red wires here. So we're just gonna disconnect those from our diode. And then, we'll crimp them in place onto the wires that we had just stripped back. Now, we'll take our wire. We're just gonna push it into the back of our butt connector, our spade terminal here, and then crimp it down. Double-check, make sure it's all the way on there. And then, we're just gonna repeat that for the other end of the wire here. All right, so we've got both of those already connected. We can go ahead and just plug them into the diode. I'm gonna pull off the rest of the spade terminals on there 'cause we're gonna be hooking those up here in just a minute. So we'll just get those out of the way. All the labeling for it's gonna be here on the diode. So that way, it's nice and easy to tell where everything needs to plug in. So car brake out, output is always gonna go towards the bulb. So we're gonna plug in the brake out into our red wire. Car brake in, that's going into the diode coming from the vehicle. That's gonna be the other side of our wire here that's going back to the rest of the harness from the vehicle there. So we got those two hooked up. We still got the tail, the RV brake, and the ground to hook up. So the RV brake's gonna be our yellow wire. This is gonna be the brake signal from our motor home when we're hooked up to flat tow. So we'll strip that one back. We're also gonna strip back the white wire that we routed over. And again, this one is coming from the taillight signal over on the passenger side. So this is actually our taillight circuit here. So we're gonna put a spade terminal onto each one of these wires. Okay. And then, we can go ahead and plug these in. So yellow is RV brake. That'll plug in here. And again, this white, this particular white wire is the one that's coming from the passenger side, so this is gonna be our jumper wire for the tail signal over here. So that's gonna plug into the tail signal. There we go. We got one more wire left over here, and that's the ground wire. For the ground wire, we're gonna add ourselves. You'll get two of these little, small kinda wrapped up white wires. This is used for hooking up your brown. So go ahead and just open that up, strip back each end of this wire. On the one end of this wire, you're gonna put the last spade terminal. And then, on the other end of this wire, you're gonna place one of the ring terminals that come in your kit. We can go ahead and slide that onto ground now. And now, we'll need to attach the ground wire. The ground wire, we're just gonna use a self-tapping screw that comes in our kit to just run it into any of the sheet metal here behind where our light is. I'm gonna put the diode and stick it in place in the location I want it first. That way, I can make sure that I'm gonna put this in a location that gives me enough room to still kinda pull this taillight assembly out if they ever need to replace a bulb in the future or something like that. So we'll get our diode stuck in place first. Just peel back the adhesive backing, and we're gonna try and tuck it down right in here if we can. And we use a little bit of alcohol to clean up the area before putting the pad in place. And then, this will give us an opportunity now to kinda just see where we're gonna be putting our ground wire here. And I'm kinda thinking we're just gonna put it straight back here, kinda just to the left of where that grommet is right there. And that'll gimme plenty of tilt to be able to tilt this out, so if they need to replace bulbs in the future and stuff, they'll be able to do that. So I'm gonna grab the self-tapping screw that comes in the kit and an eight-millimeter socket on a gun so I can run it in. So just take your ring terminal, slide your self-tapping screw through the terminal, and then hold it in the area that you're wanting to install it in. And we'll just use our socket here, eight-millimeter, to run it on in. And just make sure it's tight enough that it doesn't spin, so we're gonna go a little snugger. And sometimes, it's unfortunate there that the sheet metal's so thin that it's not gonna get tight enough to give you a proper ground. So we're just gonna move it to another spot. Sometimes, you can go up a little higher, and you can find a spot that's maybe a little double layered and we'll fill that in with silicone. All right, so after we moved it to a couple of spots, this one here, I can give it a push to the side. It's a nice, secure ground. So these other holes here, we're just gonna use some black silicone and just seal those up. So that way, no moisture can get in, no exhaust gases, or anything like that. And at this point now, we've got both our sides hooked up. We can reinstall our taillight assemblies. And then, I'll show you the path that we routed it underneath, heading up towards the front. So we're now underneath the vehicle, so we can show you the path that we routed. First, we took the wires and, you know, we went up behind our passenger side taillight. You can see the brown and the white and the green going up there. From there, we had to go across, and we're routing our yellow wire and then that small piece of white wire from our setup over here to the other side. The way that I knew how long to make the piece of white wire is I just stretched the yellow wire over and kinda just held it up to make sure it was gonna be long enough. And then, I folded the yellow wire back along the harness and cut the white wire where the yellow wire stopped. That way, I knew that my white wire here was gonna be the same length as my yellow. And then, we routed those up. And we already made our connections up there. So now, we're just gotta finish routing the wire forward. So it's kinda here in the middle is where the main harness is. It's gonna continue forward. I just routed it back over to the passenger side. And then, we just start going towards the front from here. And we just used some cable ties to attach it to the frame. And once we get to this point here, this is about where we had cut the white wire. So the section that we used over there for the jumper ends about right here. And that's a good spot. This gives us a nice, little area here to be able to hook up our ground. So the white wire here, that's continuing with the rest of our harness going forward, we're gonna ground that end of the white wire. So we just stripped it back, put one of the ring terminals in our kit on it, and ran a self-taping screw right up into here, just like we did behind the taillight. From there, the rest of our harness, and this is all four wires again now, white, brown, yellow, and green, all four of those just continue running forward. We go above the panel here. It comes out the opening here, and we just kinda stay right above our fuel and brake lines here, just kinda keeping it above each one of these. And I'll use a cable tie to attached to the plastic. You do not wanna use a cable tie and attach it to a line. Make sure you're attaching it to a bracket. We don't wanna, you know, put any anything on here that could potentially rub or allow the wire to like pull and damage our line. So we're just gonna continue on with that. Keep doing that all the way forward. Once we get to this point, we just continue following those fuel lines, staying behind 'em and cable-tying it all the way up until we get to this point here. And you should be able to reach your hand up in there and just kinda poke it up there. And then, we can head back up top and grab that wire and finish routing it. And this is where our wiring came up. Now, these other wires here, this is part of our braking system. Many braking systems will need to tap into your diode wiring. So that's all this is right here. You can ignore this if your braking system does not require you to tap into it. But if it does, that's the reason why we routed the wire up to this location to make it easy to access these wires, so we could attach our braking system components to it. But if your brake system doesn't need it, you could continue all along the bottom. But I still recommend routing it up, just so for the future, if you wanted to change braking systems, it would be easy for you to do that. Now, the rest of this wiring here, just gonna continue routing forward, which continues on up towards the front. We just kinda wrap around our air box, wrap around the side, and then we poke through an opening here next to the radiator. Now, from there, it just goes down the front, and it routes over to here. I did that routing while I was installing my base plate. That way, the fascia was off. So that's when I recommend that you, right when you're doing your base plate, that is the best time to do all of the rest of your components. Before you put your fascia back on, get your base plate on, hold off on putting this on, do all your other stuff, then you can put the fascia back on and you got a whole lot more room to route those wires. But they do just kinda rattle on the front and come out here. And they're gonna attach to this location here on our base plate. This is the mounting location for our wiring on our base plate. Now, depending on which kit you purchased, there is some options. This kit does come in either a four flat. It comes in a bare where you don't get anything. That's what we installed today was the bare version. We're gonna be installing a six-pole connector on it, but we're not doing one out of the kit. Our customer wanted to use Blue Ox components today, which is perfectly fine. We can use Blue Ox with this system, even though it's a Roadmaster wiring. So here's the Blue Ox connector right here. And it's very similar to a Roadmaster connector. The shape here on the back is slightly different but, I mean, it all hooks up basically exactly the same. On this connector, you'll have a little rubber sleeve. I already poked the rubber sleeve over the wires. Make sure you do that first. And then, I stripped back each end of my wire. From there, we'll need to connect all of our wires to our six-way connector. So if we look at our connector, there are gonna be labels on it. Right there, it says TM. We got a GD there. So those are all your labels for what this circuit is intending to function. I like to start with ground. So let's find the ground one. There is ground labeled GD. So we're gonna unscrew ground. That's gonna be the white wire that we routed up here. And then, we're gonna rotate to the next one. That is LT, which is left turn. That's gonna be our yellow wire. Next, we have RT, which is right turn. It's gonna be our green wire. The next is labeled S. We're gonna skip that one. That's gonna be for additional accessories if you wanted to install them. Oftentimes, we can use that for like a monitor light or something, but we don't need that one today. TM is the next one in our kinda order going around here, and that is our taillight circuit. That's our brown wire. We'll need that one, so we'll unscrew that. And then, lastly, you have your center pin here. This is often used for like a charge line circuit. We're not installing one of those today, so we don't need that either. So now, we're just gonna poke in our wires into each one of those slots that we just unscrewed. And then, just tighten it back down. We'll go back and start with ground again, GD. Slide in the white wire and screw it down. You wanna make sure that you're not screwing into the sheathing of the wire, that you're screwing directly on the wire. But you also wanna make sure you don't have any exposed wires sticking out above there that could potentially cause a short between the circuits here. All right, we got that one snugged down. And we're just gonna just move around down the line. So next was LT, which is left turn. That's our yellow wire. We got our green wire. And I did have some excess wire here as well before I started this. You can just trim off the excess. I just made sure I had a few inches sticking out beyond this. That way, it's easy to make my connections. But beyond a few inches, you don't really need me more excess than that. And our last wire, we'll poke that in there. If you twist it, it makes it a little bit easier to insert the wire into the slot without getting any stray strands. 'Cause that's all it takes is one stray strand to cause a short. All right. And then, I'm just gonna finish up here with this yellow one. It's a little bit up higher than I'd like it. We're gonna try and drop that down in there a little more to ensure we don't got any short issues. All right. So now that we've got all of our connections made now to our harness, we can go ahead and mount it up for these connections here. These came with the base plate, and those just happen to match up with our holes. So we'll remove those and install it right onto here. We're gonna grab an eight-millimeter socket to use the fasteners that came with our base plate. All right, we'll zip those out. So I went ahead and just removed those screws. Then, we'll slide our rubber piece down on here, and we're gonna fill this cavity up with dielectric grease. This will help seal it to keep moisture and stuff from building up in here, keep out corrosion. And we wanna be pretty generous with this to ensure that it does stay a nice, moisture-free connection in there. And another thing that I like to do real quick before i mount it, just take some electrical tape, and I'm gonna tape both sides of that boot just to make sure the dust boot doesn't slide off of there, try to hold that grease in. And it's a little bit easier to put the electrical tape on while it's kinda hanging down like this. All right. Got that guy all sealed up. That dust boot's not going anywhere. Slide our wiring back into place there, we'll insert our bolts, and then run it on down. Before I run it all the way down, I like to make sure I get both of my bolts inserted. That way, I can kinda slide the connector back and forth as needed to make sure it lines up appropriately. And we'll snug it on down. And we can easily access that. Your wiring that's kinda poking up here, if you wanted to, you could put some wire loom on it to protect it. We're probably gonna maybe put a little piece on it there just to make it blend in with the front here a little bit better. But that's basically it. At this point, we can test it out. So we got our tester plugged in now. You can also just plug into the back of your motor home and operate your lights. You'll get the same results there. We wanna make sure you have your taillights, your left turn signal, right turn signal, and brake lights. With all of our lighting signals working properly, we're ready to button up our vehicle, hook up to our motor home, and hit the road. And that completes our installation of Roadmaster's smart diode wiring kit for incandescent bulbs on our 2020 Chevy Sonic..


Info for this part was:

Employee Joshua S
Video Edited:
Joshua S
Employee Jacob T
Video Edited:
Jacob T
Employee Dustin K
Video Edited:
Dustin K
Employee Chris R
Video Edited:
Chris R
Employee Zach D
Video by:
Zach D
Employee Jonathan Y
Video by:
Jonathan Y
Employee Shane H
Test Fit:
Shane H
Employee Robert C
Test Fit:
Robert C
Employee Conner L
Test Fit:
Conner L
Employee David F
Test Fit:
David F
Employee Ryan G
Test Fit:
Ryan G
Employee Clayton O
Test Fit:
Clayton O
Employee Michael B
Installed by:
Michael B

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