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  4. Trailer Hitch Wiring
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T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

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

Item # 118745
Our Price: $71.05
You Save: 34%
Custom Fit Vehicle Wiring

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Shipping Weight: 1.71 lbs
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118745 - Custom Fit Tekonsha Custom Fit Vehicle Wiring
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Quickly and easily install a 4-way trailer connector on your vehicle with this custom wiring harness. T-One connector plugs directly into existing wiring - no cutting, splicing or tapping required. Powered ModuLite reduces strain on wiring system. 1-800-940-8924 to order Tekonsha custom fit vehicle wiring part number 118745 or order online at Free expert support on all Tekonsha products. Great prices and Fastest Shipping for T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector. Custom Fit Vehicle Wiring reviews from real customers.
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  • Reviews (27)
  • Q & A (0)
  • Videos (4)
  • Photos

Tekonsha Custom Fit Vehicle Wiring - 118745

  • Custom Fit
  • Trailer Hitch Wiring
  • 4 Flat
  • Powered Converter
  • Tekonsha

Quickly and easily install a 4-way trailer connector on your vehicle with this custom wiring harness. T-One connector plugs directly into existing wiring - no cutting, splicing or tapping required. Powered ModuLite reduces strain on wiring system.


  • Provides a 4-way flat trailer connector at the back of your vehicle to power your trailer's signal lights
    • Compatible with 5-pole, 6-pole and 7-pole adapters (sold separately)
  • Connects quickly and easily
    • Locate connection points in rear cargo area
    • Plug in T-connector
    • Run hot lead to car battery
  • Includes ModuLite power converter to ensure that your vehicle's wiring matches that of your trailer
    • Powered module connects to battery to avoid overloading vehicle's electrical system
  • Constructed of 16-gauge bonded wire
  • Comes with dust cap for 4-way flat connector


  • Maximum amperage:
    • Stop/turn lights: 4.2 amps per circuit
    • Tail lights: 7.5 amps per circuit
  • 1-Year limited warranty


This custom-fit T-One connector plugs into your vehicle's wiring harness, which is located inside your rear cargo area. You will have to remove the storage trays and some interior paneling to access this harness. Once you've plugged in the T-connector, run the hot lead up to your car battery. Connect the lead to the included fuse holder, and then connect the fuse holder to the positive terminal on your battery and insert the provided fuse.

Once installation is complete, the 4-way flat connector will be stowed in your rear cargo area.

It is recommended that you use a small amount of grease on all electrical connections - the plugs on your automobile and the 4-pole connector itself - to help prevent corrosion.

ModuLite Powered Tail Light Converter

A ModuLite power module is built into this T-One connector. Because most trailers run on a two-wire system - wherein the brake and turn signals are carried on one wire - the separate brake and turn signals from your vehicle's three-wire system need to be combined so they are compatible with the wiring system of your trailer. This power module functions as a tail light converter to combine the brake and turn signal functions of your automobile so that they run on one wire to properly activate your trailer's tail lights. Note: This will not affect how the tail lights on your vehicle operate.

With a ModuLite, your trailer's lights will be powered without overloading your vehicle's electrical system. Because the module draws power directly from your car's battery and bypasses the electrical routes that are used by a basic wiring harness, there is virtually no draw on your tail light circuits.

118745 Tekonsha T-1 T-Connector - 4 Wire - Modu-Lite Converter Included

This Product Fits The Following Vehicles

California residents: click here

Video of T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for Tekonsha T-One Vehicle Wiring Harness Installation - 2019 Buick Encore

Clayton: Hey guys! How's it going Clayton here at And today, we'll be taking a look at and I'll show you how to install, Tekonsha's T-One Connector Harness on our 2019 Buick Encore. So what our four pole trailer wiring does is allows us to tow a small trailer safely. That'll give us our turn signals, our running lights and our brake lights. And one thing I really like about this kit is our dust cover. It's part of our plug.

So we don't have to worry about losing it or falling off. And it can be used as a temporary foot wire holder. You can put it around your safety chain loop and clip it in there. We don't have to worry about our wiring.A really nice feature about this kit is it's all plug and play. All you have to do is plug our wires into our taillight wires, run our wires to our passenger side.

Then run a power wire up to our engine compartment. Overall, it's a pretty easy installation. Speaking of installation, I'll walk you through how to get it installed now.So to start our installation, we can open our trunk. We're going to have a cover right here. We can just look it up on our cargo liner and set it aside.

Now we're going to go ahead and remove our tie-downs. You'll use a 10 millimeter socket and take that out. Now we can go ahead and remove our plastic liner. All you have to do is pull up. This'll come right out.

Now we have to take out this T45 screw. This holds down our styrofoam liner. With that loosened up, we'll be able to shift this out of the way. Now we can go ahead and remove our access panel right here. We're going to use a nylon pry tool. There's going to be a little slot right here, where we can stick our tool. There's enough room to get our hand behind there. Then remove our panel.Now we can go ahead and remove our taillight plug located right there. You can reach in with your hands and pull out our plug. All you have to do is push down on this little tab. Now we need to feed our wiring up through here to our plug. I'm going to take an airline tube. You can obviously use a coat hanger or a rope with a string. Anything that you can get to drop down here. So we'll stick our airline tube down and grab our airline tube. Then I'm going to take some electrical tape, make sure to get enough tape on there, to where if your wiring does catch anything on the way up, that it won't pull off. With that taped on, we can pull it up and remove our airline tube.Now with our wiring fed in, we can grab our plug. Add our new plug from our wiring kit. You'll make sure you want to hear that click in. Then we'll take this end and put it right back on our taillight. And before we took all of our wiring up underneath our vehicle, I'm going to go ahead and re-add our panel since we are done on the side. This can be tricky because you have this cargo compartment. But you can take your time. Should be pretty easy. And before we can add our wiring, we have to take off our access panels.Then there'll be another little plastic panel here. We'll take that same pry tool and pry this out. And you don't want to pull too hard, so we don't break our tabs. And now we have our airline tube ran from our access panel down through our bumper beam and out our hole here. I'm going to go ahead and take our plugs to our airline tube and get that pulled back through. Again, you want to be careful that way we're not pulling any wiring or snagging anything. So after we got our wiring run through our bumper beam, there wasn't quite enough room to come up the outside. So we're going to go up underneath this access panel, just like we did on our driver's side.So we can go ahead and remove our plug and take our new wiring. Make sure our channels are facing up. Snap that in, take this side, plug it in there. Now what I'm going to do, since we have a little bit of extra wiring. Is I'm going to fold this over and zip tie it together. So we do have a little bit of exposed wire here. I'm going to go ahead and zip tie that to our factory wiring. And I'll repeat that on our driver's side as well. So now I'll go over our wires ran to our taillights. We can go ahead and mount our box. I'm going to use our two-sided tape. It's important when you're mounting this, that you're not going to amount around anything hot or moving. And in this case, I'm going to mount it right here behind our styrofoam tray.So we can go ahead and stick our box in. I'm going to try to move it as far back as I can. Right there it's pretty hidden. Now still give us room to run our power wire and our ground. Now I'm going to go ahead and take out our spare tire. You don't have to, but it's just going to give us a little bit more room one. When we're mounting our ground wire. Now we can take ourselves tapper and Mount our ground. You want to make sure to mount somewhere that, if you have to take your spare tire out, you won't rip this off accidentally.I'm going to go ahead and go right here. I've already cleaned it off with some rubbing alcohol. So we know we have a clean surface. So we can take our self-tapper and run our grounds. So with our ground wire ran, I'm going to go ahead and leave our spare tire out just for a little bit more room. Now we're going to go ahead and connect our black wire. So we'll want to strip it back, twist together. And I did cut it a little bit long. So we'll trim the ends. Take our butt connectors provided crump it down. I always like to get both sides, just to make sure. Always give a good little pull. Just to make sure our won't come off later. So then we'll take our black wire from our kit, twist that. Add our butt connector and crump it down. And again, I'm going to give a little tug. We know we're good. So now I can wrap this up electrical tape.So there are a couple of ways that we can go about manning our four-pole wiring. A lot of people leave our wire like this. Just put it in their spare tire compartment. And then take it out when they need it and just drape it over our gasket. Our customer wants a four-pole mounted down on the hitch. So there's a grommet down here. And I'm going to take our four-pole wiring and our power wiring. And then I'll cut a slit in the side and then we can slide our wiring through that grommet. So at this point, If you want to put all your components back in your trunk. Feel free to do that. So you'll have to add your spare tire, add the cover and our paneling on our passenger side.Now we're going to run our power wire up to our engine compartment. I'm going to try to follow the frame rail as much as possible. You want to make sure to stay away from anything that's hot or moving. I'll go ahead and run my wire. And I'll show you how I did it. I ran it right under here under our bumper beam, up behind this bracket and over our exhaust hanger bracket. Then there was a hard line right here. And I zip tied that to the hard line all the way up through here. And then right there, I came down to our brake line bracket and up our brake line a little bit, under this little shield here. And then on the other side of the shield. I came through our frame rail here, all the way up to here. And then I dropped down our airline tube. I'll tie these together and pull it up along this firewall. Now with our airline tube connected to our wiring, I can go ahead and pull this up.And again, you want to make sure this isn't going to hit anything hot or moving. Now I'm going to take a zip tie and zip tie to this factory wiring here. So we want to make sure that our fuse is not in our fuse holder. And then we're going to cut right here in the middle. Now that'll give us a good idea of where we need to cut our wire for power. So if we put it there, that should come right over to our battery pole very nicely. So I'm going to cut our wire right about here. Now we can take our wire and strip it back. Add our butt connector, before we grab our fuse holder. Strip back part of this, add it to our butt connector. Give a little tug and make sure we're good. Now I'm going to throw some electrical tape over that just to ensure any connections.Now we can check and make sure we have a good length to connect to our battery. I'm going to come right here to this bolt and that looks pretty good. So we can go ahead and strip this back and add our ring terminal. And we can go ahead and crump that down. So we're going to use a 12 millimeter socket. We'll take off that bolt. And then we can add our ring terminal. Now with our fuse connected, we can close our cover and make sure there's room. We don't have to do any trimming, which is nice.So we know we're ready to add the fuse. And we'll take our 15 amp fuse provided in our kit. Add it to the fuse holder, close our cover. And I'm going to tuck ours down here to the side. And now with our tester hooked up, we can go ahead and test everything out. We'll start with our brake lights, our running lights, our right turn and our left turn. So now that we've tested everything. We know we're ready to hit the road. That's going to do it for our look at and installation of the Tekonsha T Connector Harness on our 2019 Buick Encore..

Customer Satisfaction Score:

Customer Reviews

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - 118745

Average Customer Rating:  4.9 out of 5 stars   (27 Customer Reviews)

Quickly and easily install a 4-way trailer connector on your vehicle with this custom wiring harness. T-One connector plugs directly into existing wiring - no cutting, splicing or tapping required. Powered ModuLite reduces strain on wiring system.

2018 Buick Encore

Delivery was as promised.It took me a little longer than expected because 1 of the hitch mount was a little twisted on the driver side,and I did it solo with 2 jack to hold it in place. Overall it is installed. 2018 Buick Encore


The hitch was sent on time and in good condition, the installation was easy and fast, instructions were easy to follow, electrics kit was plug and play. Only downside is after 1 year the paint on the unit is starting to peel and rust is forming

2020 Buick Encore

I was suprising pleased how easy it was to install this wiring kit. It's mostly all plug and play connections except for a grounding wire and getting a hot wire from inside rear of vehicle to the battery in front. All the videos show that you just remove a black rubber cap slice a hole in it feed the wire through it and snap the cap back in place. But on my 2020 model the rubber cap was already being used by a factory wiring harness so you had to make a hole in the cap beside the wiring harness that was using this space. Other than that and fishing the hot wire around brake lines up through the frame up to the battery ( not hard just time consuming) it was a fairly easy installation. I definitely give this kit a thumbs up!!!


Great service as always.

2019 Buick Encore

The package shipped an hour after I ordered it and showed up a day quicker than advertised. It looks right and if it hooks up and functions as it is supposed to I will be SUPER happy. From reviews I’ve read it sounds like tech support is great but I have a buddy who teaches people to drive tractor trailers and he’s very good with stuff like this, so I’ll probably just let him hook it all up. I’ll add pictures later, I won’t be needing to use the trailer until our house is done being built. More to follow.

2017 Buick Encore

Excellent product, installed easily just like shown in the installation video. Kudos for having the installation videos available!!


Can't get any easier than that!!!


Excellent delivery thank you


Easy to install and still working perfectly one year later.

2018 Buick Encore

Very pleased with the merchandise I Purchased easy to install


Great price along with customer service! Received on time without and damage.


Arrived in a few days. Easy to install (20min)



Ashley was the epitome of professional while being very customer-centric while taking care of me.


Great people to work with, very helpful and polite would highly recommend




Was simple and easy to install. Company shipped it fast! Thank you!!

2018 Buick Encore

Installing it was easy for me.


fast processing and shipping, good pric es.




very helpful and fast shipping





Show More Reviews

See what our Experts say about this Tekonsha Custom Fit Vehicle Wiring

  • Curt Hitch for Motorcycle Towing With 2018 Buick Encore
    The Curt Class I hitch # C11527 is rated for 200 lb tongue weight and 2,000 lbs towing, most small utility/motorcycle trailers and one dirt bike would be less than this max range; please reference your trailer and motorcycles weight for an accurate assessment. I highly recommend that you refer to your specific vehicle's owner's manual prior to towing. My research, the online manual I have available (Part No. 84098804 B Second Printing), has a statement on p197 "The vehicle is neither...
    view full answer...
  • What Wiring Harness will Fit My 2021 Buick Encore GX?
    As far as wiring, if you need just brake lights/signal lights alone on your 2021 Buick Encore GX, you will only need the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118745. The T-One includes a ModuLite power converter to ensure that your vehicle's wiring matches that of your trailer. If you are looking to add a brake controller to the trailer, you will need the Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat # ETBC7 in addition to...
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  • Parts Needed to Transport 2 Dirt Bikes with a 2017 Buick Encore
    The only hitch that we have for your 2017 Buick Encore is the Curt Class I Round Tube Hitch # C11527. As long as your Encore has at least a 200 pound capacity, you could use this with a bike rack like the Saris Freedom # SA4412B to get the job done. This hitch has a weight capacity of 200 pounds tongue weight. You will need to subtract the weight 28 lb weight of the carrier to get 172 pounds remaining for the weights of your bikes. If you're wanting to transport actual dirt bikes then...
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  • Parts Needed To Tow An ATV With a 2020 Buick Encore
    While a class I receiver like the Curt Trailer Hitch Receiver # C11527 for your 2020 Buick Encore is rated to tow up to 2,000lbs with up to 200lbs of tongue weight, I do see a note in your owners manual stating "Never tow a trailer with your vehicle. It was not designed or intended to tow a trailer." While it is your vehicle and ultimately comes down to you if you decide if your going to tow you will want to keep the weight as low as possible. You will want to use a light trailer like...
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Do you have a question about this Custom Fit Vehicle Wiring?

Info for this part was:

Employee Lindsey S
Edited by:
Lindsey S
Employee Joshua S
Video by:
Joshua S
Employee Zach D
Video by:
Zach D
Employee Jonathan Y
Video by:
Jonathan Y
Employee Dustin K
Video Edited:
Dustin K
Employee Chris R
Video Edited:
Chris R
Employee Cole B
Installed by:
Cole B
Employee Alexander C
Written by:
Alexander C
Employee Shane H
Test Fit:
Shane H
Employee Ryan G
Test Fit:
Ryan G
Employee Clayton O
Test Fit:
Clayton O

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