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

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

Item # 118519

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Tekonsha Trailer Hitch Wiring - 118519
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In Use/Installed

  • Custom Fit
  • Trailer Hitch Wiring
  • Tekonsha
  • 4 Flat
  • No Converter
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. Powered ModuLite reduces strain on wiring system. Call 800-298-8924 to order Tekonsha custom fit vehicle wiring part number 118519 or order online at etrailer.com. Free expert support on all Tekonsha products. Guaranteed Lowest Price and Fastest Shipping for T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector. Custom Fit Vehicle Wiring reviews from real customers.

  • All Info
  • Reviews (10)
  • Q & A (7)
  • Videos (3)
  • Photos
  • Why etrailer?

Tekonsha Custom Fit Vehicle Wiring - 118519

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. 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 behind tail lights
    • Plug in T-connector
    • Run hot lead to battery
  • Includes ModuLite to ensure that your vehicle's wiring matches that of your trailer
    • Powered module connects directly to the 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: 2.1 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 behind the driver's-side and passenger's-side tail lights. You will have to remove the tail light assemblies to access this harness.

Tail Light T Connector Diagram

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 an out-of-the-way location within your cargo area. It is recommended that you use a small amout 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.

118519 Tow Ready T-One Vehicle Wiring Harness

118519 Installation InstructionsInstallation Details 118519 Installation instructions

This Product Fits The Following Vehicles

2011 - 2015 Lincoln MKX

2011 - 2015 Lincoln MKX

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 - 2013 Lincoln MKX

Today on our 2013 Lincoln MKX we're going to be taking a look at and showing you how to install the Tekonsha T1 Vehicle Wiring Harness with a four pole flat trailer connector. This wiring is going to provide us with all of the necessary lighting functions to not only be safe but legal. We're going to have our tail or running lights, our turn signals, and our brake lights. Now the power output is going to be more than sufficient enough to operate all your trailer's lights correctly. It's also going to have a nice dust cap, which will not only keep your terminals protected and corrosion free, but it also serves as a holder for when you're not using your four way. If you would rather have this permanently mounted in a bracket somewhere in this area, you can pick a bracket up at etrailer.com.Now that we've gone over some of the features, let's get it installed together.

To begin our install we're going to need to gain access to our hatch. We're going to start by removing our tail lights. They're going to be held in place by two eight millimeter screws. And we can just grab the light and carefully work it out.Now once we have it out, we can remove all the wiring connections from it and then set it to the side. To get the wiring off the tail light connector, all you would do is push this tab down and pull back.

I'll go ahead and do the same thing to the other side.We're going to take a pair of pliers and carefully pull these grommets out. Now we can remove our floor covering, set it off to the side as well as our spare tire cover and these little storage compartments. Now these just pull off and out. We're going to remove our threshold. To do that, you simply just push these little tabs up and we'll take our hands and pull up on it and set it to the side.

We're actually going to have to loosen up this passenger side panel here to give us some working room. To do that we'll first unscrew this hook and then starting down at the bottom we'll just use our hands to separate it from the metal. And as you can see there's actually some little pins or clips in here rather and those'll just fit into those grooves and you can just work it out. Once that is freed from itself, we'll continue to work your way up top a little ways, and then we'll actually remove two push pin fasteners down at the bottom of the panel. There and there.

And that's about as far as we would need to go.Now we're going to have to loosen our speaker assembly up to get a little working room. We're going to remove two bolts, one here and one back there. And those bolts are going to be a 10 millimeter. Now we can, lift back on our speaker and that'll give us all the room that we need.Back at our taillight grommets, we're actually going to cut a little slot in it. That way our new wiring harness can go through it. I'll just use tin snips and cut a slice about that big.Now we're going to take our new wiring harness and we're going to be using the green end for the passenger side. What we're going to do is behind the speaker, we're going to feed it through the hole that goes into the tail light area here. Now once it's through, we can put it in our grommet and that slot that we made. We're only going to need about this much wire. So where this black piece is, that's all that's going to be left in this tail light area, and then we can put our grommet back into place. We did the same thing over here on the driver's side, but it's a little bit easier because you don't actually have to remove the panel. You just take the end of the harness that is yellow and brown, then run it up through there, through our taillight opening, through the slot that we made in the grounded, and it'll look just like this.Now we can choose a spot to mount our box. You're going to want that area to be flat and clean, so we're going to clean it off with some alcohol. It's a nice flat spot back here out of the way. Before we hook it up, we'll apply our two sided tape to the box. You can peel the other side off and connect it to our harness. You'll know it's connected when you hear it clip like that and we can reach back and secure it.Now we're going to screw down our ground wire, which is the white wire with the ring terminal on the end. You want to make sure that it is secured to a piece of metal, just like the sheet metal here. We're actually going to be using the self tapping screw that came with the kit to accomplish that.Next we're going to run our four way wiring outside the vehicle. We're actually going to use this grommet to do that, so we'll remove this grommet, cut a slice in it just like we did in the tail lights, put our wire through it and put the grommet back in place. We're just going to take some RTV silicone and seal up that slice that we made in the grommet. If you need some of this you can pick some up on etrailer.com.Now we can hook up our main power wire. Now what I went ahead and did was take the end of it and I just pushed it behind this panel through here like that. So we're actually going to be connecting this to the yellow butt connector here off of our box. What we'll do is just push that end in and crimp it down to make that connection. I went ahead and used some electrical tape to wrap up our connection just for a little extra protection. Then I'll kind of just fish it up in through there to keep it secure. Now we're going to drop this wire down to the underside of the car and run it up front to the battery. The reason I ran it through this panel is because we're actually going to use this grommet.Now to allow this wire to pass through the grommet, we're just going to make a small hole and push the wire through. Now when you're making that hole, be careful not to hit the wires already running through it. I'm going to use a drill, but you could use a knife or a razor or something like that if you want to. I went ahead and pushed all that wiring through our grommet and then put some more RTV silicone on it to seal it up. Before we run our power wire all the way up to the front of the car, what I like to do is come pop our hood into the engine compartment and actually drop a fish wire or pull wire down through to the bottom side of the car. Now I'm using a piece of nylon air tubing, but you could use anything else that you might have, something like a coat hanger would work fine.I went ahead and ran our power wire up to the front. I'll show you how I did that. That grommet there, that's where we put the wire through in the back hatch area and it came down and I went over our sub frame and actually secured it along these brake lines and it kind of follows the fuel tank. Now whichever way you route it, you just want to make sure to avoid any moving or hot parts. Here it comes out from the fuel tank and secured it to this line here. Following it through there and I just put it behind our shield here, which just runs through on your brake line again, comes out, secured it up through here. I stopped about right here.Now what I did was, this is our pull wire that we dropped down through the engine department. Now I attached our power wire to it. You can pull our fish wire up through the engine compartment and that way our power wire will be exposed. I went ahead and pulled all of our slack out of our power wire and I actually just secured it with a zip tie right here. That way you don't have to worry about it falling back down and it'll stay in place while we finish the job.So then what we can do is take our included fuse holder. We'll go ahead and cut that in half and then we can kind of eyeball where we need to cut our power wire. So we're going to actually be hooking our fuse holder up right here. And if it'll come around to about there. So we'll go ahead and trim our power wire. That's always a good idea to give yourself a little bit of extra wire. You'd rather have it and not need it than need it and not have it.I went ahead and stripped off the insulation on our wires to expose the copper. Now on one end of our fuse holder, we're going to install a ring terminal and that simply just pushes over. I'm going to use our crimpers, get that attached. On the other end, we're going to use a heat shrink butt connector. Now the ones that come with our kit will work just fine. However, I like to use these because they offer a little more protection against the elements. If you want to use some of these, you can pick some up at etrailer.com. We'll just slide our fuse holder in, then you can take our power wire in, crimp that side down. We can take our heat gun.Now we can connect our ring terminal to our battery. Now when we're making that connection, you do want to make sure that our fuse is not in the holder. We'll use a 10 millimeter to loosen this nut up, place our ring terminal over it. Go ahead and just tighten our nut back back down. Now once that is connected, then we can take our included fuse, put it in and push on the dust cover.Now we can plug in and reinstall our tail lights. We're going to first take our OEM or factory connector and plug that into our new wiring. You'll hear it click. Then you know it's fully connected. Then we'll take our tail light and this connector and do the same thing. We can push our lights back in. And lastly, reinstall our bolts.Now before I put all the panels back together, I like to test everything to make sure it's working. I'm going to go ahead and test our left blinker, our right blinker, our brake lights. And finally our running lights. Since we verified everything is working, we can now put all of our panels back together. Now one tip I would like to point out is this green wire that runs along the threshold, what I like to do is use some packing tape to tape it up to it, that way not only it'll stay secure, but it won't get pinched or anything when we're putting our threshold back on.And that'll do it for our look at and installation of the Tekonsha T1 Vehicle Wiring Harness on our 2013 Lincoln MKX.

Customer Reviews

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - 118519

Average Customer Rating:  5.0 out of 5 stars   (10 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. Powered ModuLite reduces strain on wiring system.

- 118519

Every thing went according to plan. Hitch and wiring came in a timely manner. Thanks 643914

- 118519

Delivered on time . Install was easy with install video. 617644

- 118519
2013 Lincoln MKX

Same part number as Draw Tite and no cross reference needed. I purchased this part $35 cheaper than I could get from my own wholesale supply company. etrailer shipped lighting fast. Part is exactly as specified. 511358

- 118519
2015 Lincoln MKX

Great installation videos! Made installation go a lot quicker. Very easy to install. Product seems to be very durable. Good heavy gauge wire going from the battery to the controller. More than enough zip ties provided with it to secure the power line appropriately. 505382

- 118519

Great product great service everything went absolutely perfect thanks to all involved 461688

- 118519

This hitch is a quality product and is easy to install. The videos are extremely helpful. I know where I will buy my next hitch! 401462

- 118519
2014 Lincoln MKX

Excellent transaction. Thank you. 252978

- 118519
2011 Lincoln MKX

Ordering was easy. Item description was detailed. Install videos on youtube from etrailer made install very easy and efficient. Definitely recommend. 213465

- 118519
2008 Ford Edge

Easy install and hookup with simple hand tools. Highly recommend these kits. Have used one before on an 08 Edge for nearly 5 years with no issues. 183535

- 118519

Received my order in just 4 days which was great. Will order again from etrailer if I need more. Watched the installation videos which were a great help and was able to install trailer hitch receiver in about 1 hour by my self 122854


Ask the Experts about this Tekonsha Custom Fit Vehicle Wiring
Do you have a question about this Custom Fit Vehicle Wiring?

  • Trailer Wiring Harness Options for a 2011 Lincoln MKX
  • Curt trailer wiring harness # C56121 does indeed fit your 2011 Lincoln MKX. Installation will be the same as the video I have linked which features a 2013 MKX. We also have Tekonsha harness # 118519 or Hopkins harness # HM11140314 which also fit your MKX. They all install and function in the same manner but we do hear about fewer issues with the Tekonsha harness.
    view full answer...

  • Trailer Hitch and Wiring for a 2013 Lincoln MKX
  • Starting with a trailer hitch you can use Draw-Tite Class III hitch # 75992 on your 2013 Lincoln MKX. This hitch has a 2 inch receiver and is rated for 400 pounds tongue weight and 4,000 pounds gross trailer weight. I have included a link to the installation instructions for you. For wiring you will not have to splice into the vehicle's wiring at all. The wiring harnesses for your vehicle plug in line with the tail light wiring. I recommend Tow Ready harness # 118519 because the tow...
    view full answer...

  • Availability of a 4-Flat and 5-Flat Wiring Harness to Power an Air Compressor on a Trailer
  • With the set up on your 2013 Lincoln MKX, you best option will be to install the T-One Vehicle Wiring Harness, # 118519, and then use the Tow Ready 4 Pole to 5 Pole Wiring Adapter, # 20036. This the adapter will connect your 4 pole vehicle plug and 5 pole plug on your trailer. The trailer lights will be connected to your vehicle. The extra wire then can be wired up to the battery to power your air compressor. Depending on the amp draw of your compressor, I also recommend you wire in...
    view full answer...

  • Troubleshooting Factory Trailer Wiring on a 2011 Lincoln MKX, No Blinkers
  • Sounds like you have a blown fuse or relay under the hood of your 2011 Lincoln MKX. Grab your owners manual and look up the fuse box legend. There should be a section that has tow package wiring. Check and replace those fuses as necessary. It also would be a good idea to check out the wiring of your trailer. There might be shorts on the turn signal circuits that caused the fuse to blow.
    view full answer...

  • Is Tow Ready No-Drill Mount Bracket Required for Mounting 4-Way Connector to Hitch
  • When used along with the Tow Ready Mounting Bracket # 18144, the No-Drill Mount Bracket # 18140 you referenced will provide a nice bracket for your Tekonsha 4-Way harness connector # 118519 that won't require any drilling into the Draw-Tite Hitch # 75992. The No-Drill Bracket is not absolutely necessary, but it is what we typically recommend to avoid drilling into your brand new hitch or bumper. I have attached a short video demonstration so you can see exactly how this is used.
    view full answer...

  • Parts Needed to Add a 7-Way Trailer Connector and Brake Controller on a 2013 Lincoln MKX
  • In order to add a 7-Way trailer connector to your 2013 Lincoln MKX you will need to hardwire one in. First, you would need to install a 4-Way using # 118519. I have linked a video showing an example installation for you. Then you can use installation kit # ETBC7 to add a 7-Way. I have included some links that show and explain the ETBC7 installation for you. If you tow a trailer with electric brakes then you will also need a brake controller. I recommend the P2 # 90885 because it is...
    view full answer...

  • Trailer Hitch and Wiring Recommendation for 2014 Lincoln MKX AWD
  • For your 2014 Lincoln MKX the hitch I recommend is the etrailer hitch part # e98870 as this is a USA made hitch with more than enough capacity for your vehicle, is priced great, and only has the hitch opening hanging below the rear bumper which means it's mostly out of plain sight. The best trailer wiring option is the Tekonsha kit part # 118519 because it's easy to install and comes with a very reliable converter box. I attached an install video for this kit for you to check out as...
    view full answer...

Do you have a question about this Custom Fit Vehicle Wiring?

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Info for this part was:

Test Fit:
Joe V
Photos by:
Theodore B
Video by:
Andrew K
Expert Research:
Michael H
Video by:
Joshua S
Updated by:
Adele M
Updated by:
Laura H
Installed by:
Cole B
Video Edited:
Chris R
Photos by:
Zach O
Updated by:
Sarah W
Updated by:
Alexander C

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