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Tekonsha T-One Vehicle Wiring Harness Installation - 2020 Toyota Corolla

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How to Install the Tekonsha T-One Vehicle Wiring Harness on a 2020 Toyota Corolla


Hey everyone, Shane here with etrailer.com. Today I have a 2020 Toyota Corolla. I'm gonna walk you through how to install the Tekonsha T-One vehicle wiring harness. Adding the vehicle wiring harness like this is gonna allow you, whether you have a cargo carrier that needs some extra lights because it covers your factory tail lights, or maybe you're pulling a small trailer, you need to get the light functions from the vehicle to the trailer. This is gonna allow you to do that. It's gonna give you your four-pole connection, which is your brake signal, both turn signals, and your running lights.

It's gonna have a dust cap, so when you're not using it, you can cover those connections, so it doesn't get dirt and debris caught inside. Now this wiring harness is gonna live inside of the vehicle. So when you're not using it, you simply roll it up, tuck it underneath your carpet pad here, in your spare tire area. When you're ready to use it, you simply pull it out, lay it over the rubber shield, stay away from anywhere where your trunk attaches to the body there, connection points, hook up to your trailer, and you're ready to go. It's gonna give you five amps per circuit for your stop and turn signals, 7.5 amps per circuit for your tail lights.

Now, the nice thing about this wiring harness is one, it's gonna be very easy to install. Simply plugs into factory wiring behind each taillight. Two, it's gonna have a converter box on it. What the converter box does, it protects the factory wiring on the vehicle from any back feed if there's a wiring issue with the trailer. How that works is, if you have a short in the wiring, that short is gonna back feed.

If you don't have that converter box, it's gonna feed right into your factory wiring, and it's gonna cause damage to it. You could burn it up, or cause damage to any connections. Converter box is gonna stop that back feed from getting to your wiring. So what it's gonna do, it's gonna shut it down. So it's gonna give you a lot of protection when adding this.

The only thing that is a little bit difficult, and it's really not difficult, is taking the factory. or mean the power wire from the converter box, running it up, and then up and connecting it to your battery. Now you know most of the features, I'm gonna show you how I did it. Start your installation. We're gonna open the trunk, we're gonna go ahead and remove our floor coverings. We're gonna come to our threshold. We're gonna push pin fastener here, and then one on the other side. Can either put a pry tool in there, plastic trim panel tool, or if you can get your fingers right back here, they usually pop up pretty easy. That'll keep you from scratching anything. We'll pull each one of those out, and then we'll pop this up and out of the way. Pull up, and then we'll set that aside. On each side of the vehicle, this felt liner, is gonna have two more fasteners. Take your trim panel tool, get in right behind it. And we're gonna pop each one of those out, to release the lining. It makes it easier, right down here on the bottom, you have another one. You can go ahead and remove that one as well. What we're looking for, is we're looking for this green wire that goes back to a plug. You can see where it's mounted on that side wall. When you come to your felt, right up underneath, there's another faster, you pull that one out. It might give you a little extra room to get back in there. We'll disconnect that plug, and then we'll start hooking up our wiring harness. Disconnect it right here on the bottom, you're gonna push it up, and then disconnect the plug. Just like that. We're gonna take our wiring harness with the yellow cable, one's gonna go into this plug, the other end is gonna go into the plug mounted on the wall right here. In your kit you're gonna get a bundle of black wire. You're gonna strip back one end, and on one of the butt connectors, crimp it down. The black wire coming off our converter box, you're gonna add it on the other end. We're gonna take the other end of our black wire, we need to get it outside, because in another step, we're gonna run it up to the front of the vehicle, and connect it to the battery. Right behind this panel, there was a rubber plug right here in the corner. Pull that plug up, find a head screwdriver for panel tool, it allows us to go right outside the vehicle. We're gonna take our wire, and we're gonna feed it right down through it. We can take that rubber grommet, cut it 'til the center, then we can put it back in, and that'll protect your wire against that metal edge. We're gonna take our white wire with the ring terminal, there's a factory ground right here, 10 millimeter socket, remove that bolt, slide that on and reinstall the bolt. Once you get that on, you're gonna have some two sided sticky tape, grab one side, stick it on the back of the converter box, and we'll take it, and we're gonna mount it right back in this area. Right back up against that wall is a good spot for it. You just wanna make sure that your four-pole end, is out here in the middle, as well as the plugs with a green and red wire on it. And we can put this panel back in place. Our plug for our passenger side is actually gonna be right here. We'll remove it the same way we did our driver's side, and then plug everything together, the exact same way. Then we can put that panel back in place. You can do a couple of things with your extra wiring. You can take it and tuck it, and just lay it down on the bottom down here. However, your spare tire's down there. What I suggest, kind of bundle it up, and you have factory wiring that runs from one side to the other. Your kit's gonna come with zip ties. We'll just take it and zip tie it right to that factory wiring. We're gonna reinstall our threshold. And then don't forget your two fasteners that go here. Once you get out that in, we're gonna take your four-pole wire, and you can either hang it out the side before you put your floor covering back in, drive it right down in this pocket, put your floor covering back over it, it'll be ready to go when you're ready to use it. Now I'm gonna run a power wire up to the front of the vehicle, and then up to the engine compartment. Let me get it done real quick, and I'll show you how I did it. The best thing to do when running this wire to the front, is try to find some factory wiring along the way. The factory is not going to install it where it's gonna get damaged by any heat, or moving parts. What I did from here, ran it right over top of this axle, there's factory wiring right on top, so I went over to the top of it, came to here, from behind this factory line, it'll hold it up, to this side right over here, then you have a bunch of factory lines that run from here up to the front of the vehicle. I went in-between, laid them on top. Put a couple of zip ties in to hold it up there, to here, you have your pole wire from the top where my battery is, that I've fed down next to the firewall, took my line, you can tape it to it, it's an airline tube like this, you can feed it up inside. Now we can go up top, we can pull this wire up, and get it connected to the battery. We'll pull our wire up. One thing I do suggest, is once you get it to where it's tight, check underneath to make sure it's not a knot, and it's not caught on anything. Now what we need to do is grab our wire where it's gonna connect to the battery. And this cover right here, you'll notice this end, opens. If you do it anywhere else, the wire is gonna be pinched. So I'm wrapping it around the front, we're gonna ride our wire in there, still be able to close that, and cover that positive terminal. So I routed it back behind my negative cable, I can zip tie it right to this post. That'll keep it from dropping back down, wrap this in here, cut our wire, don't worry, we're gonna strip off the ends. Your kit's gonna come with a butt connector, I recommend using heat shrink, for any of your wires that are gonna be outside. It's gonna help protect those connections from corroding. Clamp it on, take your fuse holder, cut it in half, we're gonna strip back both ends. One end is gonna go in this butt connector, the other end is gonna get a ring terminal. We're gonna take our heat source, and shrink up the butt connector. That's up to you. I like to cover the butt connectors, whether they're heat shrink or not with electrical tape, gives it a little bit of extra protection. Now we're gonna take our wire, alright just like this, we're gonna run it right in this corner, connect it to our battery, that'll allow us to close that lid. Gotta make sure when making this connection, the fuse is not in the holder. 12 millimeter socket, remove the nut, install your ring terminal, reinstall the nut, reinstall your panel. And then if you wanted to, you can take this wire, there's factory wiring right here, you can zip tie it right to that. Once you've got it connected, install your fuse, then we'll test everything out, and make sure it's working correctly. Now we're gonna test out our wiring using part number I26. Left turn, right turn, brake lights, running lights. Once you've tested it out, you're ready to go. That's gonna do it for looking at and installation on Tekonsha T-One vehicle wiring harness from the 2020 Toyota Corolla..


Info for this part was:

Employee Kathleen M
Installed by:
Kathleen M
Employee Chris R
Video Edited:
Chris R
Employee Shane H
Test Fit:
Shane H

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