Tekonsha T-One Vehicle Wiring Harness Installation - 2019 Mazda CX-9

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How to Install the Tekonsha T-One Vehicle Wiring Harness on a 2019 Mazda CX-9


Bob: Bob here at etrailer.com and today we're going to be taking a look at the Tekonsha T-One Vehicle Wiring Harness with a 4-Pole flat trailer connector on our 2019 Mazda CX9. Now our Tekonsha wiring is going to give us a 4-pole flat trailer connector and where we have all the required lights to get down the road safely. Whether we're towing a trailer or we have some other kind of hitch mounted accessory that uses lights, our wiring is here to provide us our taillight signal, our turn signals and our brake lights. One thing I do want to mention is we chose to mount our wiring on the outside of the vehicle close to the hitch so it's easily accessible and ready for us. And we're also using a 4-pole bracket to mount it so it's nice and secure, but our bracket is not included with the wiring. But you can find it here at etrailer.com.One thing I really like about our wiring is there's no cutting or splicing at all on the factory wiring.

It's made specifically for the Mazda CX9 to have a factory tow package. So we can simply remove a few panels on the interior of the back hatch. We'll find a plug that we can plug your harness into. And we just got a matter routing into the outside if we want to or we can keep it in the trunk where it was designed to stay. But either way it's an extremely straightforward installation and in fact, we'll show you how to get the wiring to the outside.To begin our installation, we want to open up our rear hatch and we're going to remove all the floor coverings.

So pull this one out. We can set it aside for right now. Then on either side of the hatch we can pull out the cover trays and set those aside as well. Pull out the spare tire cover, and then on each side, we'll have these plastic trays. We're going to pull both of those out as well.

Just kind of grab the bottom and lift up. There are some plastic clips in there, you might hear them pop. Those are just those releasing and if you have any of them that get stuck in there in the body of the vehicle, it's perfectly fine. We can pull them out using a flat blade screwdriver or a trim panel tool. And then on the bottom of the panel you'll find a little notched area with a circle on it.

That's where this push pin is going to go. So we just want to make sure we get that first rib lined up. We'll just slide it into place like that. We'll go ahead and pull out the other panel on the other side as well.So with all those panels removed, we're going to come to the rear threshold plate and we're going to need to pull it out as well. So if you grab the bottom and you just lift upward, it'll release those clips. And we're just going to work our way across and so we can get it all the way out. We'll set this aside.Now on the passenger side, underneath the very edge of our threshold, we're going to have a push pin right by this carpeted section. We have our flat blade screwdriver and you want to come underneath the center section and pop it up, which then will release the tension and we can pull the rest of the pushpin out. Now on the inside panel of the passenger side, we're going to have our tie down hook at the back here. I'm going to grab a flat blade screwdriver and we're going pop the cover open, so just come underneath it and it'll flip down and that'll expose the nut that's holding it in place and pull it out with a 10 millimeter socket. It is a little pin that's holding it in place, but if you pull it, it'll come out.At this point, I want to pull this section away so we can get access behind here. So you can use your hand if you can get it back there to grab the panel and just start pulling away. If not, I suggest using a plastic trim panel tool that we don't damage either the weatherstripping or this panel here. Well, we'll just get our trim panel tool in and we're just going to start separating that panel so we can get it far back enough to get access into this area.Now, if you can't get back there far enough, we can come up to the upper section. We'll flip open our tie down hook and remove that bolt using the same 10 millimeter socket. That will give us a little bit more wiggle room to get that panel open.Now that we have that panel broke loose, we don't have enough room to get it out far enough to reach our hand in or that you can see. So we're going to come back to the outside. We're going to remove the jack as well as this compartment here so we can move the panel out a little bit more and have more working room. This panel is held in just like the other side, just some pushpins on the bottom. So just grab it and lift up. And again, if they get stuck in the body, we can pull them out, put them back into the bottom. Now if I pull the panel back and we look inside, we'll see that they're going to have two plugs right next to each other. One of them is going to be unoccupied. That's going to be our factory tow package plug and that's going to match up with the plug that's on our wiring harness. Now I suggest taking a look at the plug and getting your new wiring harness kind of in position, because it's extremely hard to see to reach in there once we have it in place. So I'll reach in, make sure that my plug's facing the right way and I'm going to give it a quick tug to make sure it locked into place.Now if we come back from the plug a little bit, we'll find this bolt holding another sensor against the body. That's going to be a really good spot for a ground. So we can take the white wire with a ring terminal and attach it right here. So I'm going to grab a 10 millimeter socket and remove that bolt. I'll slide my ring terminal through the bolt. Make sure it goes around and you do want to make sure you replaced that sensor and mount it back up. So just get it loosely started so it won't fall down and we'll tighten with our 10 millimeter socket.Well, the final step is going to be mounting our converter box. Now we can either use the eyelet on top and take a zip tie and zip tie it to some factory wiring back here. Or we can use the double sided tape. I'm going to remove the backing off one side. We'll grab my converter box, make sure it's stuck to the back and it's nice and secure. Remove the backing off the other side and we just want to find a nice flat spot of metal that we can stick it to that it's not going to interfere with the panel going back in place.Now, at this point you want to make sure you route your wire underneath that side panel and we can start putting all the panels back in place. Now if you're going to leave your wire on the inside of your Mazda, then we can put everything back and we're done. You just want to store your wiring by your spare tire when you're not using it. But if you'd like to mount it on the outside by your hitch, we'll show you how to do that once we get these panels back in place.And we've got most of our panels back, we left our threshold off because we're actually going to be zip tying the excess wire along the back here with some factory wires. But we want to remove our spare tire so we can get access underneath it. So I'm going to take a 21 millimeter socket and loosen up the subwoofer on top. Pull the bolt out, grab the subwoofer. And for now I'm just going to rest it on top of the seats up here so we don't have to disconnect anything. Then we'll grab our spare, and just move it out of the way so we can get access underneath. Now,, underneath that spare tire we have a couple of rubber plugs that are in the bottom of the trunk pan. So you take a flat blade screwdriver, I'm going to pop one of these out. Now. If you look down, you'll see the heat shield, but it's extremely close to the edge so we can send our wire towards the back of the vehicle and we should be able to get access to it.Now with the dust cover in place, you kind of have to move it out of the way and push everything in kind of one piece at a time. Once you get the end of it in there, we can start pushing the excess wire towards the back of our Mazda so we can get it towards the hitch. Then to make sure we don't have any kind of leaks, whether it be water or exhaust, I'm going to cut my grommet, so there's a slit right about to the middle and use a pair of scissors, cutters, whatever you have. It's just plastic so we should be able to cut through it fairly easily. And then just take our grommet, the plug, slide our wire in place. We'll push it back in, make sure it's seated all the way. And I'm going to secure my wires to make sure there's no excess and it's not going to interfere with the spare tire going back in place.Now that everything is secure, I'm going to come back with some RTV silicone. I'm going to seal up the area that I cut in my plug. I don't have to worry about anything getting inside my Mazda.Now with our wire on the outside, we can start putting our spare back and all the other panels on the inside. Don't forget to go back and you want to fix your weatherstripping at the back of your threshold in the side panels to make sure it's in the right position so we don't get a bunch of water in our hatch.Now, our wiring came down right above our hitch, above the heat shield, so now we just want to make sure we route it towards our hitch and we can use the dust cover to secure it whenever we're not towing or on our hitch that we have, we have a bracket already mounted and we're going to be attaching ours using a four-pole bracket. Now if your hitch doesn't have this bracket on there already, it's all right. You can pick up a short bracket or a long bracket along with a four-pole bracket to mount everything. Everything will be really easily accessible for you. So with our four-pole bracket, I'm just going to take the included hardware, I'll drop it down through the holes, there will be two screws holding it in place. Then I'll grab the included lock nuts and just loosely get them in hand, get them on hand tight. I don't have to worry about the bracket falling. Then we can tighten everything up. These are lock nuts. So we can actually just hold the screw on top with our finger, grab a 10 millimeter socket, and tighten it up. We don't have to worry about trying to get a screwdriver on top.Now we'll just take our 4-pole connector, we're going to push it through the bracket until those little ridges on the top and the bottom there are on the outside of that little lip. That way when we push on our trailer connector, it won't push it through. I always suggest just finding any of that excess wire you have and I'd suggest zip tying to the hitch. Just try to keep it as far away from the exhaust as you can.The final step of installation is going to be checking our wiring and make sure all the circuits are working properly. So I went ahead and plugged in my 4-pole tester and we'll start running through our lights. Here we can see our taillight function is working as well as the left turn signal, the right turn signal, and our brakes. All we have left to do now is hook up to our trailer and hit the road.And again, I'm Rob here at etrailer.com and that'll finish up your installation and your look at the Tekonsha T-One Vehicle Wiring Harness with a 4-pole flat trailer connector on our 2019 Mazda CX9.


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Info for this part was:

Video by:
Andrew K
Video by:
Kathleen M
Video by:
Jonathan Y
Video Edited:
Jacob T
Video Edited:
Chris R
Installed by:
Cole B
Test Fit:
Brent H
Test Fit:
Robert C

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