Curt T-Connector Vehicle Wiring Harness Installation - 2017 Toyota Prius

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How to Install the Curt T-Connector Vehicle Wiring Harness on a 2017 Toyota Prius


Hi there, Prius owners. Today on your 2017 Toyota Prius, we're going to be taking a look at and showing you how to install Curt's 4-Pole Flat Trailer Connector vehicle wiring harness. And this is what our harness looks like when it's installed. That's right, you can't even see it, because it's hidden underneath our panels, so when you're ready to use your wiring, simply lift up on the panel, and it's stored here inside. When you've got it pulled out, simply just drape it over the back, and when you close your lift gate here, it's going to pinch it between the weatherstripping. It's not going to cause any damage to it, just make sure you avoid the striker at the very middle.And now we've got our 4-pole Flat Trailer connector here at the back, which provides us with all of our necessary lighting signal.

This includes our left turn signal, right turn signal, tail lamps, and brake lamps, which will keep us DOT compliant in all states. And one of the things that I really like about this harness, is that it has an included module. I'd show you the module, but it's hidden behind a panel there, but this module is hooked to the battery up at the front, so this module receives its own power. The module is then teed into the lighting circuits on our Prius here, and it monitors those circuits for signals. So whenever you're inside and you hit your blinker, the module will see that, and then using the power wire at the front, it produces its own signal, which it then sends out to this 4-pole Flat Trailer connector.What's nice about the module producing its own signal, is that if you had a fault on your trailer, and it was a short or something and it caused a circuit to blow, it wouldn't affect your vehicle at all, the module would attempt to shut the circuit down, and in the event it was unable to shut it down in time, the fuse that is installed for your module would open, so you can repair your trailer and then simply replace the fuse, and you're back on the road.

You'll also receive a dust boot with it, that can be used to keep out any dirt, debris, and moisture when it's not inside your vehicle, and it can also be used if you maybe just got done unhooking it and you haven't stored it away yet, and you're just leaving it out, maybe for another accessory or something, you can store it on the safety chain loop here with the dust cap. We'll begin our installation here at the back of the vehicle. We've got the lift gate open here, and we're going to pull out the panels here at the back.The ones on the floor, they just pull right up, just grab your handle and pull them out. You can actually just push them forward, if you've got the seats laying down like that, just get those out of the way, and the same thing with these panels here as well. And these all just pull up.

Sometimes they get a little stuck. There is a little pin in there, so you might have to just grab the piece and give it a tug. And now that we've got that out of the way, here at the back, we're going to remove the threshold, these little hooks right here, they have bolts inside that we're going to remove using a 10 millimeter socket. So we'll just zip these out, and then we'll just set those aside as well. Once both of them are zipped up, the panel will just lift straight up, so we'll just take it on one side and just pop it up, and then grab the other side and pop it up, and then it will come off and we can just set that aside as well.Now we'll turn our focus to the sides here.

These panels need to be moved out some. The little hooks here for like a netting, we're going to remove those. At the bottom, you'll see there's a small notch. You'll need either a screwdriver or a little punch, or a pick to press on that little tab. I got one here, and we want to just push up on that tab, and you see it'll just pop right out of there. We're going to remove the other side as well, so we're going to be taking off the one over there. Now, further back on our panel, you're going to have another little attachment here. This is just a little plastic cover that we can just pull out, and once you get it out of the way, there's a bolt behind it that we're going to remove with a 10 millimeter socket. And of course, we're going to get the one over on the other side as well.We can now start removing the panel. I'm going to start with the weatherstripping here. Just kind of peel this back, we don't need to peel it off real far, we need to kind of get it out of the way. And then our panel here is just going to pull straight outward, but you will have several little pushpins that kind of run down the side. You'll see there's the plastic where it kind of goes into almost like a tube shape, that's going to go down to where a pin is to attach it. So use a flat-bladed screwdriver or a trim panel tool to just kind of get up in there and get behind it a little bit, and then pry outward. And we're just going to continue pulling out until we can access our wiring. So if we follow this wire up here, it kind of goes towards where our connector is, but our connector is actually located right here. It's this one with the smoother black sheathing on it, and it goes to this little tab right here.We're just going to grab the connector and just pull it off of this tab, and that'll make it easier to work with, we got it right here, you can see there's four wires that go into each side of the connector. Press in on the release tab there, and then you can just pull it out to separate it. We can now grab our harness for our new module, we're going to use the yellow wire part of our harness, and this is just going to route around the paneling. Well then bring it over here to where our factory connector is, and it's just going to plug in line in between those two pieces. The other one can be pretty far up there, you should be able to reach it, and plug it in. Now that we've got the driver's side hooked up, we're going to do the passenger side now, and it's basically the same thing. Just take your green wire now instead of your yellow one, and this, we're going to route across the back here, so it's just going to go underneath our threshold. Let's get this wire kind of separated out some.Oh boy. And then run it across. We're going to tuck it behind this paneling, just like we did on the other side, and then this ribbed sheathing here is our harness that we need. So again, it's easier if you just pull this off of here, because you connect your side, you got to depress this up against the body. So it makes it really difficult. Press in on that tab, release the two. We'll then just take our new harness here, and plug it in. Those can just go back up in there hide behind your panel. Then we can return to our module. Here at the module, we've got a couple of wires that are coming off of it that are shorter. You have your white wire, which is your brown wire, and this one has a ring terminal on the end. And then you also have your black wire. We're going to go ahead and start preparing these wires because we're going to mount the module shortly, but we need to have these connected because it's really difficult to access them once we mount the module behind there.So pre attaching the wires just makes things easier. You'll have a large amount of black wire, and we're going to use this black wire to extend the wire. That's coming off the module. We're just going to connect these two together, using the included butt connectors. So we'll strip back this end, and then we're going to grab our butt connectors and crimp them together. We're just going to strip our wire. Then we'll take one of the yellow butt connectors, slide it over the wire, crimp it down. And then on the other end here, just right over to our module. So now we can turn our attention to the white wire. This is our ground wire, and we're going to attach this one to a bolt located back here behind our panel. We're just going to remove this bolt right here. We can use a 12 millimeter socket to remove it.Once you get it broke loose, a lot of times these bolts will just come out by hand. We can now take the white wire with the ring terminal on it, and we're going to feed it back behind our panel. You're likely going to have to bring your module with you some, because the blanks of the white wire's kind of short. And we're just routing it up to an existing bolt. There's one right here that we can slide our ring terminal on. So I'm just going to remove that using a 10 millimeter socket. And once we get this loose, the bracket that it had on it is going to come off with it. That's okay. We can actually just slide our wire behind the bracket and it'll poke out just like that.So now we're just going to put this bolt back in. Again, you might have to grab that module and pull it towards you, just because of the length of the wires. Pretty short, When you're putting this back on to pay attention to that, there's a little notch on the bracket. You just want to make sure you get that notch back in the little hole and then snug it back down. We can now mount our module that we've got all the connections made on this side. We're just going to mount it right here, behind our cover. So I'm just going to clear off an area here. So it's nice and clean and we're just using a little bit of rubbing alcohol on a pad or rag. And then we can grab our pad, peel off one side of the adhesive backing, and stick that to our module. And then we'll just peel back the other side of the adhesive backing, and then we can just fix it in place.It's a little hard to see just because how tight it is up in here. But we're just pushing it up against the paneling there. And you want to hold it there for about 15 seconds to ensure that you have good adhesion. Now we need to route some wires outside. The harness that has the brown and the red, as well as the black wire that we had attached, those needed to get outside. And there's a grommet located right here on the back, just behind your spare tire. We're just going to pull this grommet out of the way, and then we can take our wiring here and just poke it right on through that hole. We can then grab it from down below here momentarily. There is some panels we'll have to take down down below to access it. Same thing with our black wire. Just get that guy pushed down in there as well. You don't need to push the whole thing through right now. It's usually easier to just pull it down, but you want to have enough down there that you can grab.We're now underneath the vehicle, and the panel here at the center where it goes around our hitch, we'll need to take that down so we can get access to the wires that we'd pushed through the grommet. There are a couple of push pins, two here at the very back. And one here off to the passenger side, slightly towards the front. We're going to remove those with a flat-bladed screwdriver or a trim panel tool. There's several little notches around the pin. Just get your blade in between the notches and then you can pop the center down. And once the center pops down, the pins will just pull out. It's going to be the same for all these pins. Sometimes they get a little stiff, they've been on there for a while and got some dirt in them. So just kind of work your way around. Don't pry too hard on one particular little spot, try pushing in a notch on the other side first. Once the pins are removed, you'll have one fastener here that you can remove using a large screwdriver.It does just unscrew. You want to give some downward pressure because these are just plastic screws and they often don't want to screw without a little assistance and it'll just pop off and we can set it aside with that panel out of the way, here's our wires. They we're actually just sitting there right behind the panel so we can grab our black wire and pull it the rest of the way through same thing with our red and our brown little harness here. We're going to plug this in, and this is located right up here. You'll see this harness where it comes around and it kind of clips into a little spot on the trunk pan there. That's the connector that we want to disconnect to plug our red wire into. So it's usually easier if you just pull this off of here, because it's kind of far up in there. It's really tight with the hitch here. So once we get that popped out of there, it's just like up top.There is a connector on one side, you'll find your release tab here. Just press in on the release tab. And then you can pull the two apart. We'll go ahead and pull it down and give you a better look. There's our release tab right there. So we'll then just take our new harness here, plug the two pieces together. And then we'll plug these two together. And then we can turn our focus back to the black wire. This wire needs to route up to our engine compartment so we can connect it to the battery to get power for our module. I'm going to go ahead and route this wire now, and then I'll show you the path that I took to get it there. We've routed our wire. We went just above our hitch, and then we tucked it behind the paneling right here. We come out right on the other side of the paneling right there. And then we stay above our rear suspension and our exhaust, because we want to avoid anything excessively hot, like our exhaust here and any moving components like our suspension.So we just stay right up on top of those until we come out here on the other side of this plastic panel. From here, we just routed it around the fuel tank. And once we get around the fuel tank, we then go above this plastic panel right here, and we just stay above this plastic panel. I just pushed it in from the side here all the way up until we come out the front of this panel right here. This last little one is a bolt here, but you can easily just poke it in right here. And then it'll come out this side without having to remove that bolt. From there I do just tuck it right around this body mount bolt right here. And from here is where we're going to go up to our engine compartment. I've already used a fish wire from up top that I just pushed down. We're using a piece of airline tubing, but you can use anything that's fairly rigid, but does have some flexibility in it so you can get it down. A metal coat hanger works really well.I just used electrical tape to attach it to it. And then now when we go back up top, I can just pull our pull wire, and then we can get our wiring into the engine compartment. Here you can see the fish wire that I had fed down. I just pushed it right down the side here. And then after I pushed it down, I was just able to grab it with my hand down below when I was routing that wire. I always liked to push this down before I route the wire, so that way, while I'm down there, I can just grab it and go. Then we just pull it up. After you pull it up, it's not a bad idea to just go down below and just double-check to make sure that the wire pulled all the way up, because it's possible it got caught on something and you've got a loop hanging down underneath. After pulling the wire up, I like to zip tie it, and this'll ensure that it can't fall back down after we have pulled it up. So we're just going to zip tie it to this factory harness right here.So we can just trim that off. And then we'll just set this aside for now. We'll have to trim it to length, but I'd like to go ahead and get the fuse harness installed first so I know what length to cut it. So we're just going to lift up on this panel here, kind of pull out a little bit on the sides, and then that'll just pop up. We're going to attach our harness to this post here. We're going do a little bit of prep work on the harness first though, it does have little pre-stripped ends, but I find that they're not stripped quite enough so I have to strip just a little bit more off. And we're going to crimp a ring terminal onto one side of our harness. It does come included with our kit. Just slide that on there. Now we'll crimp it on. And then on the other side of our harness, we're going to crimp on a butt connector.Now this butt connector I highly recommend that you upgrade it to a heat shrink butt connector, which you can get here at etrailer, as this wire lives outside the vehicle where it could potentially come into contact with moisture. And this is going to seal up and prevent any moisture from getting inside, ensuring a long lasting connection. Now that we've got that side crimped on, we can go ahead and attach it to our battery positive. Make sure you don't have the fuse installed. We don't want to accidentally short anything. So we're just going to remove this nut with our 12 millimeter socket. Then we simply just take the ring terminal, slide it on, and then reinstall the nut. Now we can take our black wire, and we're going to trim it to length. Our fuse harness can hang out right here on top of the battery. So we're going to trim it about here. I always give it just a little bit of excess just for future repairs or maybe adding additional accessories and things like that. We'll strip it back now.And this is just going to crimp to the other side of the heat shrink butt connector. We can now grab our heat gun and shrink that down. Now we can insert our fuse into the harness. And at this point, once the fuse has been installed, our system should be operational so we can test everything out. I recommend testing it out before you re-install your panels and things like that, just in case there was an issue or something like that, a loose connection, you can easily get in there to make those repairs and get it up and going. So we're just going to plug our tester in at the back. You can use your trailer, but I highly recommend a tester, which you can get here at etrailer, because if you have a fault on your trailer, your circuits might not work because of the trailer faults and you won't know which is the issue, the vehicle or the trailer. So if you use our tester, you can ensure that your vehicle's working properly. So if you have faults on your trailer, you can correct those because you know for sure your vehicle works.So here at the back, we went ahead and grabbed our 4-Pole and I went ahead and slid the dust boot on it, since it does come provided in your box, we're going to take our tester now and plug the two together. And now I'm going to operate the lights and we're going to ensure everything's working properly. In some instances you can just turn your ignition switch on to operate the lights. And other times you may need to start the vehicle to produce all the signals. So we are going to have to start it to make it work. Gone ahead and started it. The engine might kick on here, make sure that you have your left turn signal, right turn signal, tail lamps, and brake lamps. So here's our grommet that we had from before where we passed our wires through, I'm going to take my snips and just cut down the side of it here. And this is going to allow me to slide by wiring in between that little slit there. So I'm just going to slide that in between there. And then we can push our grommet back into place.It is going to be a little bit tight because you've got those extra wires in there. So just kind of work at it for a little bit until you get it all in there. Here we go. And now that we've got it in there, you do get some black silicone in your kit. Just take the cap off, flip it over and then you can open it up. And we're just going to cover up this slit and our wires right here to seal this back up. Now, at this point, we've got it sealed up. We're just going to be reinstalling our panels in reverse order of how we removed them.When you're putting your paneling back in, I recommend you just take your wiring here and you can bundle it up underneath the main panel. And I like to take the wiring here and use the dust boot. It's just like a little loop to kind of hold stuff together. Just kind of bundle it up there, loop it, and then it kind of keeps it nice and neat there for you. And then don't forget your panel down below. And that completes our installation of Curt's 4-Pole Flat Trailer connector vehicle wiring harness on our 2017 Toyota Prius.


Questions and Comments about this Video

Info for this part was:

Installed by:
Jeff D
Video Edited:
Joshua S
Video by:
Zach D
Test Fit:
Brent H
Test Fit:
David F

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