Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

Video Transcript for Curt T-Connector Vehicle Wiring Harness Installation Guide - 2025 Kia Sorento

How we doing today neighbors Ian with etrailer here and today we're gonna be taking a look at and then installing the Curt custom fit wiring harness for 4-pole connector on our 2025 Kia Sorento. Let's go over a few features and see if this can be a great product for you. The Kia Sorento is a popular vehicle and even with the 2025s, we see no exception to that rule. And when it comes to having proper lighting on either your accessory or trailer, there is not a current factory option that we've seen coming on the Sorentos. So to be able to get your 4-pole wiring, which is gonna be your three main functions of turn signals, the tail lights, and then those clearance lights, this Curt connector is going to be a great option to be able to tie directly into the tail lights on your vehicle, giving you all those functions here to your accessory or trailer. As I said, this is gonna be a ModuLite type system where it's gonna hook directly behind our taillights to the OEM wiring and we'll include a control module that's gonna live here on the driver's side.

That's going to prevent any type of back feed or issues that you may have coming from your trailer or accessory protecting your OEM wiring on your vehicle. Now when it comes to the install for this, there's a few tips that I wanted to give before I give the entire presentation of how to put this onto your vehicle. One thing we did run into is that our mounting location on the driver's side here under the plastics underneath the vehicle actually made it to where the wire coming to our passenger side taillights behind me was just a little bit short, so I would suggest possibly having some spare wire and more heat shrink butt connectors, which we're gonna address in the video available to be able to extend that wire if need be. Additionally to the kit for our wiring, we did add our 4-pole connector bracket and a short bracket to attach that directly to the hitch. It is a no drill bracket that just includes a clamp.

So I would highly suggest if you're gonna be putting the wiring on your vehicle to grab these with your order. And as I said before, I am gonna walk you through the entire process of how we hook this up to this vehicle to help you get yours on your vehicle. But if you happen to watch the video and think to yourself, I don't wanna try to tackle this, please do use a dealer locator on the website. It's gonna help find a trained professional in your area that can get this installed for you. But for all those DIYers, let's go ahead and hop into it and we'll get it taken care of.

Now, since our plugs are going to be attaching to the factory harness here behind the taillights, we will need to remove those taillights on each side. I've already got the driver's side done and the procedure is the exact same on both sides. So these little tabs will open up if you push down on the top and move out of the way, exposing two Philips head screws that we will need to take out. And we'll set both of those screws aside so that way we keep track of them. Now we can just give those taillights a wiggle, get any debris out of the retention points that it's held on by and we'll get our hand back behind this top upper edge, kind of push up on the bottom and pull away.

And if we need to, we can use a plastic trim panel tool, get on the backside of our taillight and start working it back towards the rear of the vehicle. Once that pops loose, we'll very carefully take our connector. There's a little push tab here, push down on that and pull away and that will unplug. Now we're gonna be running the wires up through the pocket here behind the fascia. So just to make a little bit more room for us, there's two push pin fasteners that we'll just take out and set aside. That's gonna give us a little bit more wiggle room that way if we wanted to come up on the inside of the pocket, we've got the option to do that there. Now we need to fish a wire or something down through the inside of the fascia in that pocket. I'm just gonna be using a spare piece of airline, but you can use the coiled wire that they send for the power wire as the option. So run that down, reach up back behind the fascia, then we'll pull that down and one thing you do want to check is underneath back behind that fascia. We do wanna stay away from any hot or moving parts when we're setting all this up. So we do have the exhaust right here. We're just gonna double check the routing of how we're coming up through that fascia and see how that's gonna look. Now on the driver's side, once we've got that taillight removed, we're gonna hang out under the vehicle for a second here. There was a plastic panel with three push pin style fasteners just like we had at the taillight and then two 15 millimeter plastic nuts. Once you've got the push pins out, you can just get those plastic nuts loose by hand, but you can also use that 15 millimeter socket to help get those off. Now we're gonna mount this box up on the driver's side here under where that panel was. I believe the best spot for us is gonna be right here. Now the kit will come with a single self tapper. You can either use that for the ground or you're mounting for the box. We're gonna be using it for the box and then have an additional screw added for our ground. (drill whirring) And we're going to deal with the white wire that's got the ring terminal on the end of that. That's gonna be our ground. So what I'm gonna do is route that over the top of the box and we do need to go into some fresh metal here. So we'll just get that set with another self tapper. (drill whirring) Now the wires remaining that we have hanging off of this are gonna be that 4-pole wirings. We'll just hang that kind of by the hitch just so it's out of the way. And the two we're gonna focus on at the moment are going to be this bundled set of brown, red and yellow wires here. And then our green wire going across. So this is going to be our driver's side plug, again, we're gonna run that fish wire down through the pocket, grab onto this and pull that up there. But first we're gonna run over the passenger side. So I'll find a good routing for that and then kind of show you how I've got it over to the bottom of our fascia here. Now following that green wire that we've run over to the passenger side, it's gonna go up above the main bumper beam pretty much above our hitch just following the OEM wiring all the way across, going up above the mounts so that way it's safe from the exhaust here and then into the pocket following up to our taillight. Now additionally with the kit you're going to get this long wire set that's going to be routed to the battery at the front of the vehicle. I've already got that routed for us and that's gonna be tying into our black wire off of the control module. So of course we'll have to find a good place for that to be connected. But first I wanted to go over the routing of how I got this up to the engine bay and the battery up there. So starting here at the fender liner, we've got it attached to a hard brake line and I actually followed that up over the axle assembly here in the rear and then inside the pocket, zip tied again right there still following those brake lines we've come up over the axle assembly completely and we're gonna go around the driver's side of the fuel tank still tying into those hard brake lines since those are gonna be running to the front for us and we're continuing to follow that same pattern. This does come loose with just some 10 millimeter bolts that hold it up in place and another one of those 15 millimeter plastic push style nuts like we had in the back and still continues to go up those hard brake lines all the way to the firewall and up to the battery. Now again, we need to route the wiring back here. So I did add on some additional zip tie just sticky holders that are gonna help keep that wire routed over to our black wire here. So I'm gonna strip back the end of our wire going up to the battery and I'm gonna be using heat shrink butt connectors on this. They are not included with the kit, they just come with regular butt connectors. I would suggest since this is gonna be living outside of the vehicle to upgrade to some heat shrink butt connectors which can be purchased with your wiring order as well. We'll crimp on the end coming from our battery, come back over to our wire coming off that control module, get that stripped. Make sure we're gonna be clear as far as our routing, should be good to go. So we'll get our other end and our heat shrink butt connector here and crimp that down. Now we'll come back with a heat gun, shrink down that but connector to keep it safe and we'll secure the rest of that wire up with some zip ties. Of course, your routing may look a little different than ours just 'cause we've got access to a few more hardware options here. But of course can be just zip tied directly to the wiring there if need be. Now once we've got that routed up to each side, we're gonna hang onto that taillight and keep it close 'cause we're gonna need that as soon as we're hooked up. And we've got one in that's gonna be a mimic of the OEM harness and one that is a mimic of the plug on the taillight. So that one for the taillight will go to the OEM harness and then we can take our taillight and use that other end to plug directly into the bottom of the taillight on each side and that will click into place and we can return the taillight back where it was. Now here at the engine bay we've got our power wire routed back to the rear of the vehicle and we're gonna zip tie that up wherever we see fit and what's gonna work best for us. But we do need to add in our fused link. It's gonna come with both in strip like this one of 'em, you're gonna attach the ring terminal, just crimp that onto that bare wire exactly like we did with the heat shrink butt connectors in the back and we will add an additional heat shrink butt connector on the other side of our loop. You do wanna make sure you've got the fuse out before we go to hook all this up. We'll crimp to that and then I'm gonna get all the extra slack out of our wire here, get it zip tied to something nice and secure. More than likely this stud here at the back or can wrap that around the back of our battery. Trim off a good chunk of that excess that we have and then strip that in the back, add our fused link here and crimp down and heat shrink that. (heat gun whirring) Now we're gonna pull back the cover for our positive post and I'm gonna be using this stud here of course if that stud is occupied or maybe you can't get the nut off of that, you can add it to any of the other ones. We're just gonna go with this to make it easy for video purposes. So that's going right there. Put our nut back on. Get that snug down, then we can put in the 10 amp fuse and close that lid up. And we'll go back and double check one more time after all this is hooked up that we do have good signal coming out. So you can either hook a tester up like we're gonna be doing or you could hook up your accessory or trailer and test all of the functions that way. Now running through our functions, we'll start with our left turn signal, then that right turn signal, our clearance lights on and clearance lights off and then that brake light. Now with everything tested and we've confirmed that it is working well, one additional thing we're gonna be adding to this neighbor's vehicle here is the short bracket and then the 4-pole bracket. So they're not included with the kit, but a wonderful addition to the back of this vehicle here and gonna give our 4-pole wiring a good place to be able to live. Now I'm gonna wrap that 4-pole wiring the exact same way that we did for the green wire that went over to the passenger side. Have that come up and over. Then we need to grab the dust cap and throw that on. And we'll take the cap, run that head through the slot here, then up and over the wires. Then we can push our 4-pole wiring into place and then we'll add the cap onto that to help keep it safe when not in use. And with all that tested and complete, we can go ahead and get our plastic panel back on the underbelly of the driver's side, get all of our hardware back in place for that underside splash panel. And that's gonna do for our look at and installation of the Curt custom fit wiring harness for 4-pole connector on our 2025 Kia Sorento. My name's Ian with etrailer and I appreciate you watching.