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Tekonsha Trailer Wiring Harness Installation - 2019 Toyota Sienna

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How to Install the Tekonsha Trailer Wiring Harness on a 2019 Toyota Sienna

Today in our 2019 Toyota Sienna. We're going to be installing Tekonsha's T-One vehicle wiring harness with four pole flat trailer connector. There are two versions of this harness available depending if you have an SE model or not. The installation is going to be the same regardless of which one you need. You'll want to use our fit guide to ensure you're getting the correct harness for your vehicle. When you're ready to use your wiring, simply pull it out of its storage compartment, drape it over the back, and just shut it into your lift gate.

Just make sure you avoid the latch at the middle. It'll pinch between the weatherstripping and that's okay. It's not going to cause any damage to it. It'll help keep it in place.This harness is going to provide your trailer with all the necessary lighting. Let's include your left turn signal, right turn signal, tail lamps and brake lamps, keeping you DDOT compliant and all states.

The module helps protect the circuit, so if there's any shorts or faults on your trailer, the module will shut down that circuit rather than opening any fuses and causing any faults with your vehicle. The harness itself has a dust cap to keep out any dirt and debris and showing a long lasting connection. When you're all done with your harness, it lives inside the vehicle. You simply wrap it up and store it in your jack Compartment.Okay, we'll begin our installation at the back of the vehicle. We're going to start by removing our under shield here as our wiring is going to need to feed from one side to the other across the back.

So in order to access that, this cover needs to get out of the way. We'll begin our installation at the back of the vehicle by removing our under shield. There are five bolts across the back that we're going to remove using a 10 millimeter socket.There's one Phillips head screw on the driver's side you'll need to remove. There are then seven push pin fasteners that we'll need to remove to remove those. So simply take a flat blade screwdriver or trim panel remover tool.

Work your way underneath of it and pull it down. We'll repeat that for all the ones that are remaining. There's a small black piece as well that this slides into. You want to take those out as well so you don't lose them there. Then for plastic nuts you'll need to remove, they've got kind of a plus in the middle of that you can put your screwdriver in and just want to unscrew those. I like to put a little bit of downward pressure on these when unscrewing them.We'll repeat that for the remaining fasteners, we can then pull our panel down and set it aside. Now that our cover is out of the way, we'll begin on the inside and we're going to remove our taillight assemblies on both the driver and passenger side. We'll use a 10 millimeter socket to remove the bolts here and then you're going to want to pull the tail light rearward to get it to release. Take a trim panel tool helps out a lot, if you stick it in between the body and the light here to help you push it rearward. Once you get it to pop loose there, we can disconnect our electrical connectors. To remove the connectors, you want to press it on the release tab and then pull it out.We'll repeat the same process on the other side. Now we're going to remove the rear threshold. There are three hooks that run along the back. You'll want to flip those up along with the cover and remove the bolt located behind it with a 10 millimeter socket. We'll do that for the other two. Now that you got the bolts out, if you pull outward on it, you can remove the entire thing and that'll make it easier to get the threshold off. Now we can grab the threshold from below and pull upward on it to release it and we'll set it aside.Now we'll pull our weather stripping away and we need to remove the panel located here. We don't to take it all the way off, we need to pop it out, so just get your screwdriver back there, start at the bottom and work your way up. You'll see some tabs along the way. Those are the ones you want to hit, so we'll get those pried out and that'll allow us to use pull this panel back so we can access where we're going to be routing our wiring. There's a cover just to the inside where we pushed it loose. If you get your hand behind it you can push outward on that panel and we're just going to take that off. That'll give us an access hole to get to where our wiring is. On our passenger side. We're going to do the same thing, popping the panel out and then we want to remove the cover located here. You just press in on the tab there and that'll pop out.We can now take our harness and we're going to use the green wire, the red and brown wires. Those connectors are going to be routed to where our wiring was for our taillight assembly here. So we're going to take it behind this panel and then we're going to run these from the inside through this hole here. And now we'll just connect our wiring. The connectors here are going to be unique depending on which style Sienna you have. Using our fit guide, you should get the appropriate harness and just match those up and plug them in. This will be the only difference in your installation between the SE models and the non SE models. And you can take your new harness connector and plug that into your taillight assembly.The excess wiring can just be poked back in the hole when you go to reinstall your taillight. Now inside of our jack compartment here, there's a grommet located in there and you can just push that out. I'm on the other side. I'm going to pull it out so you can see the one I'm talking about. So I'll pull the grommet down here and you can see me poking my thing this through. Now we'll take the black wire that comes in our kit. We're going to feed that up through that grommet, pull it inside, and this is going to connect to the black wire coming off of right module. This is our power circuit. We're going to need to route across and up to the front, so we'll strip back our wiring here.I like to strip a little more than what's on the module pre-stripped already. We'll use the yellow butt connector that comes in our kit to connect it to our black wire. Now if you've watched our videos before, you might be asking, well you usually use heat shrink butt connectors instead of the ones that come in the kit. That's only because those are normally outside the vehicle. This lives on the inside, so it really doesn't need to be heat shrinked and then we'll put the other end of that butt connector and that black wire that we routed in.Now we'll run our yellow wire over to the driver's side where it will need to make its connection behind the taillight assembly. We're going to just route this along this threshold here so it'll be hidden behind it when we reinstall it. Now on our driver's side, we're using a piece of fish wire. This is just some airline tubing. We poked it in the hole where our connectors come through for our taillight assembly, and then out through this here. You may be able to finagle it in there with your hands, but it's pretty tight, so I'll just make it easier on myself, we're going to use this. The yellow wire that we routed over, we're going to take that up the side of this panel here and pull it through here.And we'll take some electrical tape. We're just going to tape that to our fish wire and harness just to hold those two together so we can pull that through the opening where our tail light goes and then we'll just pull our wiring through and you're going to have plenty of excess here. You can tuck that up inside the panel back in there. If you used the fish wire go ahead and just remove that and then connect your harness to your factory connector just like we did on the passenger side. Now we can take our taillight assembly on this side and plug it back in.You're going to have a new harness connector, the one that we just installed and you'll have one factory connector and you can poke that excess wiring back in because this factory connector is quite a bit shorter and then we can reinstall the taillight on the side as well.Our wire that we ran across, we can clean that up now using the zip ties that come in your kit. We're just going to zip tie that to this inner wall here behind our threshold and that'll just kind of keep it straight up out of the way when we reinstall our panel. That way it doesn't get caught on anything, causing any damage to the wiring. We can start reinstalling our paneling back here now. Set our threshold back on. Click it back in place and then you can reinstall all of your brackets here.Once you've got all those re-installed, you can just push those back down. Well now I need to attach our ground wire. So this can go pretty much anywhere in this compartment here. We're going to use the self tapping screw to run it into the paneling here. Self tapping screw comes provided with your kit. You'll want to use a quarter inch socket to install the self tapping screw. We'll now take the double stick tape that comes in the kit, peel off of one of the adhesive backings and stick it onto your module and we'll peel off the other backing and we're going to just going to stick it right above our ground wire here on the flat surface up in there and you just want to hold it there until it stays nice and secure. Now we'll use the zip ties in the kit to just keep this nice and clean up in here and we're just going to wrap it all together in a nice little bundle. We can then reinstall the screws for our taillight assembly.To avoid our exhaust, we routed our black wire back here to our hitch to keep it up above and then across the center. Then we went up above our differential, secured it to our factory wiring and then went down alongside of our fuel tank and we kept it alongside the fuel tank all the way here until we reach our paneling here I did remove a couple of the 10 millimeter bolts here just to drop that paneling down to tuck my wire up under it just to keep that wiring all up above this paneling. Once you get it to the front of our paneling here, you're going to need to get it up to the engine compartment. To do this, I took a fish wire just like we did in the back and I just poked it down from our engine compartment down here and you might have to come down here and look for it and then pull it down.Once you find it, go ahead and take your wiring to that and we're going to use it to pull our wiring up. So we've got our wiring pulled up using our fish wire and we're going to go ahead and secure it to our factory harness here because you really don't have a whole lot of wire left after making that run. The Sienna's pretty long. So it is enough to get to where we need it to get to, but it's short enough where it might fall back down there after we separate it so I like to zip tie it first. Now we can strip back this wire that we routed up and that's going to connect to our fuse harness that comes in our kit. The fuse harnesses looped around on itself so just want to cut it about midway, so kind of fold it in half there. Cut that. Strip back both ends of your fuse harness and on one end of our fuse harness we're going to crimp on a butt connector.Now this one we did opt to upgrade from the one that comes in our kit to a heat shrink butt connector since it lives outside of the vehicle. This will keep out any moisture to ensure long lasting connection. The other end of this connector connect to our black wire. The other end of our fuse harness will connect to the yellow ring terminal that comes in our kit and then this will connect to our battery positive post here. We'll remove the nut with a 12 millimeter socket, then you'll slide your ring terminal over top of the stud there and reinstall the nut. Take a heat gun and shrink down your butt connector. Now open up your harness and install the fuse that comes provided with it. That's a 15 amp fuse. It should just slide in.We'll close it up and we're now ready to test everything out. You can now plug in your trailer or tester light like the one we have here to verify everything's working. You could pick up one of these testers, at if you need one. Make sure that you have your left turn signal, right turn signal, tail lamps, and brake lamps, and with everything working properly, we're ready to reinstall our under shield. Tuck our wiring back in the panel on the back and hit the road. When you go underneath to reinstall your under shields, you also want to put that grommet back in that we removed to get our wiring up. Before you put it back in, take a pair of scissors or snips like we have here and just cut a slit in that metal fold right over the wiring, making it easy to reinsert.That'll simply slide over the slot that we cut and then poke back up into the frame. Now you can take some silicone as well and squirt it around here to further seal it. And if you need some silicone, you can pick some up here at With our panel back in place, we're all set. When you're not using your wiring, you can simply wrap it up and store it in your Jack compartment here.And that completes our installation of Tekonsha's T-One vehicle wiring harness with four pole flat trailer connector on our 2019 Toyota Sienna.

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