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

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

Item # C56218
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Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. T-connector plugs directly into existing wiring. Powered converter reduces strain on wiring system and is made using SMT to ensure superior performance. 1-636-306-4830 to order CURT custom fit vehicle wiring part number C56218 or order online at Free expert support on all CURT products. Guaranteed Lowest Price and Fastest Shipping for Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector. Custom Fit Vehicle Wiring reviews from real customers.
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  • Reviews (80)
  • Q & A (0)
  • Photos
  • Why etrailer?

CURT Custom Fit Vehicle Wiring - C56218

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

Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. T-connector plugs directly into existing wiring. Powered converter reduces strain on wiring system and is made using SMT to ensure superior performance.


  • 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 a tail light converter to ensure that your vehicle's wiring matches that of your trailer
    • Powered module connects directly to battery to avoid overloading vehicle's electrical system
  • Constructed using surface-mount technology (SMT) for consistent, reliable performance
    • Maximizes trailer light yield and intensity while producing minimal heat
    • Ensures superior operation in rough road conditions
  • Comes with dust cap for 4-way flat connector


  • Maximum amperage:
    • Stop/turn lights: 3 amps per circuit
    • Tail lights: 6 amps per circuit
  • Limited 1-year warranty


This custom-fit T-connector plugs into your vehicle's wiring harness, which is located behind the driver's-side and passenger's-side interior trim panels in your rear cargo area. 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.

Once installation is complete, the 4-way connector will be stowed in an out-of-the-way location within your 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.

Powered Tail Light Converter with Surface-Mount Technology

A tail light converter is built into this T-connector. This converter is a circuit-protected, battery-powered unit that bypasses the electrical routes that are used by a basic wiring harness. As a result, there is virtually no draw on your tail light circuits.

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 the trailer. This converter combines 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.

Curt builds each tail light converter using surface-mount technology (SMT). This method of construction involves soldering electronic components directly to the surface of a printed circuit board. SMT eliminates the need for leads, which are used in older through-hole technology. The result is a circuit board that is smaller yet provides more routing area and that offers superior performance, reliability and durability.

Curt SMT Circuit Boards

Circuit boards constructed using SMT have been shown to perform better under rough conditions with excessive vibration than those made using the through-hole method. And where would vibration be more likely to occur than in towing applications? Curt converters also produce less heat, leading to increased durability and longer life. In addition, lower levels of resistance ensure better performance, especially for parts that operate at higher frequencies.

Each Curt circuit board is made using high-quality components that are pieced together in the most technologically savvy fashion, leading to greater predictability and reliability in functioning.

56218 CURT T-Connector - Surface Mount Technology - 4 Wire

Installation Details C56218 Installation instructions

This Product Fits The Following Vehicles

California residents: click here

Customer Reviews

Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - C56218

Average Customer Rating:  4.8 out of 5 stars   (80 Customer Reviews)

Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. T-connector plugs directly into existing wiring. Powered converter reduces strain on wiring system and is made using SMT to ensure superior performance.


Plugged right in. Hard part was getting a wire up to the battery but that’s typical


I was a little wary of the installation but the videos were extremely helpful and I got it done without any spiteful language.


Tied in like a dream.
I actually was
able to use power from cigarette lighter outlet in the rear of my transit connect on passenger side for power making the install that much easier


Works great


Good value, still working well after one year on my 2014 Ford Transit Connect LWB Passenger van. Install videos were helpful.

2016 Ford Transit-Connect

I love the etrailer it only took me 55 minutes to install I watched a how to video it was a great help , thank you very much

Ford Transit Connect

The install was a bit more involved than expected (on the ford transit, there seem to be no possible way to run power from the front to the rear, inside the vehicle, had to do so under side) but the etrailer video made it clear what needed done and kit itself was perfect for the job in everyway.

2014 Ford Transit Connect

I was kept informed of orders progress and was able to track it within 2hrs of delivery. Shipper did an excelant job box looked like new and product was in excelant shape when unpacked. Great how to instruction I read twice and checked under vehicle for corresponding access points. It went together in 16 mins and I didn't even jack up the vehicle. E trailer has great products with great staff and support. Well done crew!

Product still performs flawlessly
Jerry A - 12/27/2015


I installed the hitch and wiring In about 2 1/2 hours

2014 Ford Transit Connect

I installed the hitch, but had an accessories place put the wiring in as part of another customization. I was a little spooked when I opened the instructions, said I'd have to run the ground wire all the way to the front, to the battery, (gulp! on my new car!) but I didn't recall seeing any note about why it can't just ground to the frame or something else nearby, so, though I bolted the receiver on no-brainer when I got the package a year ago, I had them do the electrical installation just a few weeks ago, as they're better set up to route and feed that ground wire. The hitch section has no issues, installation went absolutely by the book, no surprises. As far as I know no problems with any of the harness installation. I will say, I particularly like the large safety chain attach loops on these newer receiver models, much easier to feed the safety chain than other receivers I've gotten from these guys. Over the years when I've needed trailer stuff, I don't shop anywhere else.

2017 Ford Transit Connect

Excellent plug and play kit. Battery terminal connector is not good though, minor issue.

2017 Ford Flex

This is an excellent product and everything fit nicely together. This product was used on a 2017 Ford Transit Connect XLT 7 passenger wagon. It was somewhat difficult to install on this vehicle as the rear access panels alone did not provide sufficient room to access the connectors. We had to partially remove the right rear and left rear panels by popping the plastic retaining pins out in order to pull the back panels far enough out to access the connectors. The rear seats do get in the way but assembly can be made by having a helper flex panels back far enough to access connectors without damaging panels. We followed the video provided by etrailer completely with the exception we ran the power wire up over and behind the insulated wheel well material on driver side rear wheel rather than down brake line and under heat shield. We also added plastic conduit to protect power wire from battery down to where it enters body leading to back. Total time took about 3 hours with two people and of course with not elevating vehicle. I advise at least 6 inch elevation.


The Curt wiring kit all went together easily. I put the module on the R side vs L. I had power on the R already and had a convenient grommet to drop the trailer plug wiring thru for a permanent installation using the Curt flat 4 bracket. Doing this tho I needed to reverse the R and L turn wires and all worked well. Works great!


The trailer hitch works great. It was easy to install.
The wiring harness was easy to install but i went threw the firewall instead of going under the vehicle.


Assembly was a little more difficult than the video shows with connect t connectors because the "right" connector on each side is more difficult to locate and get christmas tree fasteners loose. I chose to route the 4 pin connector through same route as power wire and had to cut grommet to do that. Routing the plug through the fender opening to get to underside of vehicle required me to trim some bosses of each side of plug and use a long thin rod to guide plug completely through. I preferred this to having the trailer plug loose inside the vehicle. It was worth the hassle. I resealed the grommet afterwards with sealant. The biggest word of caution is the amount of black power wire provided does not give you any extra to work with getting to battery on long wheelbase wagon. I had to add 3‘ to be able to pull it up to battery and work with it.


Ive ordered a few lighting kits and other such things from here...

Shipping, timeliness and everything has always been on point and as agreed.

I havent had any problems, but this is a company that reaches out and gets in front -encouraging feedback, rather than waiting to see whos bold/dissapointed enough to take the time to complain.

I havent installed my new wiring kit yet- but i will- theyre always simple- etrailer even puts install videos up to further simplify the process- if I have a question- theyll be there- I know they will.

I have used, am using, and will continue to use for my needs
thanks guys!!!


I bought two of these kits and have installed one of them, video was very helpful and informative took me a little while longer when it came to getting under the vehicle wiring but worked out very good . I put the hitch and wiring harness to move a small trailer around have hitches and wiring kits on both transits.


The hitch is going to do a good job. I installed it by myself. It was a little more difficult that way but the hitch went on easy. Wiring in the back went ok. But running the power wire was a complete pain in the butt! Unless you have a lift under order to get completely under the vehicle. It was impossible to run the wire under the heat shield as shown in the video, the van sits too low to the ground. I ran the wire along the plastic body trim to the driver wheel well where I was able to get it up the the engine compartment to attach to the battery. The product it self is good. This is more of a two person job to get the job done easier. I like the product but would get help next time.


I made a mistake and unplugged the wrong wire. Etrailer really went out of their way to help me. I will always use them if I need anything else that they have. Thanks Pete


The wiring worked good, I am glad this is available to hook the turn signals and brake lights up on these new vehicles. Wire harness is different on these new cars, not like the old days,,

2016 Ford Transit Connect

easy install. no vehicle wiring harness butchering. plug and play, run one positive wire to the battery under the hood, add a fuse and you're good to go.


This is the second vehicle where I’ve used one of the Curt pre-made wire harnesses. Great product, easy installation. The etrailer install video was a great help. If you have the passenger version of the van, you will need to remove the seat belt winders to get to the rear light plugs - they require a T50 torx.

2019 Ford Transit Connect

Arrived fast and in great shape. Was easy for me - with better than average mechanical skills - to install in about three hours including the wiring harness which fit perfectly to my Ford Transit Connect. Satisfied with everything - what more can I say?

Ford Transit Connect

Received my hitch and wire harness yesterday as promised. Excellent quality. Now all I have to do is get them installed, would do it myself but my Ford Transit Connect is a bit low to work on, on my back. I'll have my mechanic do the work, very good man. Thank you Etrailer. Sorry no pics yet.


I set aside a whole day for install expecting to cuss a lot and spend a couple hours troubleshooting wiring but all done in about 3 hours ( because I took my time running wire where I thought it offered the best protection against damage. Love the wire fish springs that guide the bolts where they need to go.
etrailer included everything you'll need down to wire ties and lugs. Very happy customer!

Show More Reviews

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

  • Can 12-Volt Connection for Powered Taillight Converter Be Connected to 12-V Outlet
    This is a common question. Theoretically, what you propose could work but it isn't recommended. Drawing the power directly from the battery helps isolate the vehicle's expensive to repair electrical system from any short circuits that could occur in the trailer wiring, which is why the trailer harness manufacturers recommend installing a direct battery connection. I've linked to the installation instructions for the Curt # C56218 trailer wiring harness, an install video and a help article...
    view full answer...
  • Curt Wiring Harness Compatibility with 2018 Ford Transit Connect
    I reached out to my tech contact at Curt and they have confirmed the fit of the wiring harness # C56218 for the 2018 Ford Transit Connect on the Titanium, XL, and XLT trim packages. Do you have a different trim package?
    view full answer...
  • Gauge of Power Wire for the Curt Trailer Wiring Harness part # C56218
    The gauge of the wire that runs to the battery for the Curt harness part # C56218 that you referenced is 12 gauge.
    view full answer...
  • Can Curt Trailer Wiring Harness be Installed on a 2014 Ford Transit Connect with LED Lights
    Ford probably thinks that the trailer wiring harness # C56218 draws all of the power it needs through the tail light wiring. But it doesn't. This harness powers the trailer lights from the vehicle battery and only uses the tail light connection on the vehicle for the proper signals to send back to the trailer lights. LED tail lights on the vehicle would not pose a problem.
    view full answer...
  • Are LED Trailer Taillights More Likely to Blow Fuses than Incandescent Bulbs
    LED taillights would not cause trailer wiring circuits to blow as they actually draw considerably less than incandescent bulbs. So that means there is a short on the wiring somewhere on the trailer. If you have no circuits active on your trailer wiring and you are getting continuity from the power wire of a circuit to ground that would indicate that circuit is shorted out to the trailer frame most likely due to cut or exposed wire that is contacting the frame. You'd need to go over the...
    view full answer...
  • 4-Pole Trailer Wiring Harness for 2014 Ford Transit Connect
    Many of the 4-pole trailer wiring kits we sell will install at the vehicle's tail lights. The harness connectors on such kits install in between the vehicle plugs and the tail lights themselves. For the 2014 Ford Transit Connect we have three such products, all shown on the linked page, and all of these use custom connectors selected to match those on your vehicle. Of the three we have I recommend the Tekonsha # 118613 since we find their wiring products to be the most reliable. If you...
    view full answer...
    Image 1 for
  • Recommended 4 Flat Harness For A 2016 Ford Transit Connect
    The powered black converter boxes from Curt are not available separately, so I do recommend replacing it with a custom fit, powered option. We do have the # C56196 converter, but it is not a powered unit. With your 2016 Ford Transit Connect not having enough power to get the lights on a trailer working though, I do not recommend this option. With that being said, these do go out over time and I have found that the Tekonsha T-One Vehicle Wiring Harnesses, like the # 118613, are the superior...
    view full answer...
  • Load Resistors to Allow Wiring Harness to Operate with LED Trailer Lights
    LED type trailer lights use very little power, about one-tenth the amount required by standard incandescent light bulbs. This can cause some wiring systems to not "see" the trailer lights because their current draw is so low. In some cases a wiring harness may not function correctly if used with LED lights unless a load resistor is installed at each LED light unit. We offer 2-piece ceramic load resistor kit # DI34ZR which will allow your harness to operate properly with LED trailer lights....
    view full answer...
  • Is Drilling Required to Install the Curt Hitch part # C12123 on a 2014 Ford Transit Connect
    You will not need to drill any holes in your 2014 Ford Transit Connect to install the Curt Hitch part # C12123. Check out the installation instructions I attached for this hitch as well. For trailer wiring you would want the Curt Wiring Harness part # C56218. For a ball mount you would want the part # C45521, pin an clip part # F-4, 2 inch ball part # A-82, 1-7/8 inch ball part # A-80.
    view full answer...
  • Parts Needed to Install Brake Controller in a 2016 Ford Transit
    To install a brake controller in your 2016 Ford Transit Connect tou will need to start with a 4-way (if you do not have one). For that you would want the # C56218. From there you would need to convert the 4-way to a 7-way so that you can install the brake controller. For that you will want the Brake Controller Install Kit and 7-Way Adapter part # ETBC7. I attached installation instructions and an install video for this product as well. For a brake controller I would recommend the Prodigy...
    view full answer...

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