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Tekonsha T-One Vehicle Wiring Harness Installation - 2012 Toyota Tacoma

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How to Install the Tekonsha T-One Vehicle Wiring Harness on a 2012 Toyota Tacoma

Rob: Hey everybody. Rob here at today/ we're going to be taking a look at the Tekonsha T1 vehicle wiring harness with a four-pole flat trailer connector. Now our wiring harness is going to provide us with all the lights we need for our trailer to get down the road safely like our brake lights, our turn signals, and our tail lights. That way when we're pulling a trailer with our Tacoma, everyone knows if we're slowing down changing lanes, or if we're driving at night, they can see the trailer. Now it is going to give you that four-pole flat trailer connector, which is one of the most common trailer connectors out there. Now it is compatible with adapters, so you can bring it up to a seven way if you need to.

This is an extremely easy installation. It's just going to simply plug in behind our tail lights and then run our wire down to the hitch so we can have our connector here. Now, what I really like about our wiring harness is it's going to have a built-in converter box.That's not only going to take the signal from our Tacoma and turn it into a working signal for our trailer, but it's also going to protect our Tacoma's wiring. So if there's ever a problem on your trailer, it's going to prevent any kind of backfeeding. So you don't have to worry about the electrical system.

Now again, the installation is extremely easy. We're not going to have to cut or splice anything at all. In fact, let's go ahead and walk through the installation together so you can have the competence to do it at home.To begin our installation, we want to open up our tailgate and we're going to come right to the inside edge where the inside of our taillight is. I'll grab a 10 millimeter socket so we can loosen up the bolts and pull the taillight out. We're going to have one at the very top and then one at the very bottom.

We're not going to have to worry about any of the other bolts.Whenever you're pulling your taillight out, you want to try to pull straight back as much as you can, because we are going to have a few alignment pins, and we don't want to twist it too much where those are going to break. So you should be able to get a grip underneath and then right on the side, pull our taillight out. Now if we look on the back here, we're going to have one connector and a lot of bulbs. Should only have to disconnect this connector here, pressing on that tab. If the connector comes out, it's all right because it will just slide right back into the tab on the taillight housing.

Might be a little bit easier to disconnect that way.Push in on that tab and separate the two connectors. We're going to put our taillight aside where it won't get damaged and we're going to move to the other side and pul; that one out as well. So then we have our taillights out. We're going to grab our wiring harness and we want to start with the T-connector that has the yellow and brown wires on it since we're on the driver's side. Now one of these is going to match exactly that's on our truck and the one is going to be the mating one, because this is actually going to plug in line with our taillight circuits and plug our taillight back in. So we'll find the two connectors that are going to mate up together. Before I make the connection, I always like to put some dielectric grease in the connector and that's just going to help prevent any kind of corrosion from building up inside and any moisture getting in there. Just put a little bit of dielectric grease in there, plug our connectors in.What I like to do is take the rest of my harness. We're going to have the green T connector and your four-pole wire. I'm going to send all of this down. There's a hole where our wiring's going to go down. We can just send it down right there. Then we're going to take our green wire and run it over to the passenger side. It's a little bit of a small hole because we already do have some existing wiring going through there, but there's plenty of room to get the connectors and the full plug through just might have to move some stuff out of the way, start feeding it through the opening. Then once we have a little bit down there, we can always just reach underneath and start pulling the slack out.Now, in the back of your converter box, you're going to notice that you have this square piece of double-sided tape. That's so we can secure our converter box to a flat piece or a flat surface, but you also have this tab right here that you use a screw to attach it to. I'm just going to use the double-sided tape, but I am going to clean the surface first. Just kind of wipe it down with some rubbing alcohol and make sure there's nothing on there. I'm going to mount mine right here on the inside of that pocket. So it'd be out of the way of our taillight, but it'll still be close by. Push on it, make sure it sticks nice and good.Now we also have this white wire with a ring terminal connected to our T-connector over here. This is going to be our ground wire. Now there's a few different options of what you can do. You can use the included self-tapping screw in your kit, or you can use any one of these studs that are in the back pocket here, because not only are they going to give you a self tapping screw, but they're also going to give you a lock nut. So I'm just going to loosely put it in place and then we'll grab that 10 millimeter socket and tighten it up. I just want to make sure that ring terminal doesn't move and it's not loose. With this side all done, we'll go ahead and put some dielectric grease in the connector. We can plug our taillight back in.Just want to make sure you hear that click and locks in place and give it a quick tug. Make sure it is locked in. Then we can just put our taillight back in and secure it with the fasteners that we took out originally, I'm going to route my green wire along the back of the bumper here until I can get over to the passenger side. We're going to use the same method of just kind of reaching underneath and pushing our wire up so we can make it a connection over there. Now for your four-pole wire, you want to do the same thing, but you want to stop right around the actual receiver on your hitch. That way we can have our wiring close by, just maybe leave yourself a couple inches so that you have room to plug it in and use a few zip ties to tie everything up. Now I will say the kit doesn't come with a whole lot of zip ties. So you may want to pick up a handful just so you can attach it to the hitch or something else back here when you're routing everything.The passenger side's going to plug in the same way. The only thing I do suggest is that you will probably have a little bit of excess wire. What I like to do is pull all that excess into the taillight pocket and then use a zip tie to anchor it to the existing wiring that way we don't have to worry about it falling down and the slack is up top. So there's no reason to worry about anything catching anything. Then we can just simply plug our connectors in and make sure everything is lined up and put our taillight back in place and resecure it with the hardware. The final step of our installation is going to be testing the wiring to make sure all the circuits are working properly. Now I'm using a tester here because it's going to let me know if there's a problem on my truck. If you're using your trailer, it's going to be a lot harder to diagnose if it's on the trailer or truck side.So I always suggest using a tester when you're checking your electrical components, but I had an extra set of hands in the truck right now. They're going to run through our lights and we can verify that they're all working. So you go ahead and turn on the headlights. We can see that circuit is working. Left turn signal, please. That signal is working. The right turn signal. You can see that's working. The brakes. All right, with everything working properly, we're ready to hook up to our trailer and hit the road, but that'll finish up your installation and your look at the Tekonsha T1 vehicle wiring harness on our 2012 Toyota Tacoma.

Antonio C.


Jon G Thank you for the help

Antonio C.


I have 2018 Toyota Tacoma I wander in the work in my truck Or you are there different one in the you Have a one let me know I want to purchase please

Etrailer Expert

Jon G.


This wiring will not fit your 2018 Toyota Tacoma. You'll want to use the Tekonsha # 118685 instead. This installed similarly to the one in the video but you'll end up routing a power wire to your vehicle battery to power your trailer wiring. I'm also linking the installation video of this on a 2017 Tacoma that you can check out.

Info for this part was:

Employee Andrew K
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Jacob T
Employee Kathleen M
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Kathleen M
Employee Chris R
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Employee Aidan B
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Employee Cole B
Installed by:
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Employee Randy B
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Employee Brent H
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Employee Robert C
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Employee Ryan G
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