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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 # C56191
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Custom Fit Vehicle Wiring

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C56191 - 4 Flat Curt Custom Fit Vehicle Wiring
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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 - no cutting, splicing or tapping required. Converter is made using SMT to ensure superior performance. Call 800-298-1624 to order Curt custom fit vehicle wiring part number C56191 or order online at etrailer.com. 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 (32)
  • Q & A (5)
  • Videos (2)
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Curt Custom Fit Vehicle Wiring - C56191

  • 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 - no cutting, splicing or tapping required. Converter 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 - no cutting or splicing of wires
    • Locate connection points in trunk
    • Plug in T-connector
  • Includes a tail light converter to ensure that your vehicle's wiring matches that of your trailer
  • 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: 5 amps per circuit
  • Limited 1-year warranty


This custom-fit T-connector plugs into your vehicle's wiring harness, which is located in your trunk, behind the driver's-side and passenger's-side tail lights. You will have to remove the rear scuff panel and pull back the felt trunk liner to access these connection points.

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

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.

Tail Light Converter with Surface-Mount Technology

A tail light converter is built into this T-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 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.

56191 CURT T-Connector - Surface Mount Technology - 4 Wire

Installation Details C56191 Installation instructions

This Product Fits The Following Vehicles

California residents: click here

Video of Curt T-Connector 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 Trailer Wiring Harness Installation - 2015 Ford Fiesta

Today on our 2015 Ford Fiesta ST Hatchback, we'll be installing the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector, part number C56191. We'll lift up the cover, set it here to the side of our trunk latch so it doesn't get damaged, then we'll close our hatch gently on it. Then we hook up to our trailer. The reason you want a 4-pole flat trailer connector like this is so that you can hook up to most every trailer out there. You have your industry standard tail lights, turn signals, and brake lights on the trailer so you will be in compliance with all federal and state laws while you're towing a trailer. When we're done towing our trailer, and we're all unhooked from the trailer, we can just take our wiring here, reinstall the dust cover, open up our back hatch, lift up our spare tire cover here, and just tuck it down here out of the way. That'll keep it protected, and it's easily accessible whenever we need to tow a trailer. Here's what our wiring kit consists of.

We have our actual converter box here with our 4-pole flat trailer connector coming off of it, our connectors to the driver side of the vehicle, and a ground wire. Then, our connector to the passenger side of the vehicle. We have a bag of hardware, some zip ties to help secure the wiring, a self tapping screw for our ground wire right here, some double sided tape to secure the box to a flat surface in the vehicle, nice little dust cover here to protect our trailer wiring connector. Now that we've gone over what our wiring harness comes with, we'll show you how to install it. We'll begin our installation by opening our rear hatch. We'll pull up on our floor covering here.

The Fiestas are kind of neat in the fact that they have this nice little catch right here, so when you push this up, it clips into place and holds it out of the way for you. On the corners of the center trim panel piece, there's two plastic covers here. Stick a flat head screwdriver in them, pop them out, and we'll have access to our screws that hold it in place. We'll do the same on the other side. Underneath the covers, there we're some T30 screws.

We'll remove these. Then we'll pull out, and then up. Set that aside. Behind our tail lights on either side, there's a Phillip's screw here. We'll remove these. Do the same on the other side.

Now we'll grab our carpet. We have access to our tail light connector on our driver's side here. We'll do the same on the passenger side. Just fold this down out of the way. We'll unplug it on the passenger side. We'll go over to the driver's side and do the same. We'll take our connector here that has the red, yellow, and brown wire, and we'll connect it on over to the driver's side. The male end will go to the female end here. Then the female end will go to the male end. We can take our converter box now, find the white wire coming off of it right here. We'll take our self tapping screw, and we'll secure it to this metal part of the body down here. Take our double sided tape here. inaudible 00:04:07 our converter box, there's a side that has six dots sticking up, and then a reset side here that's square. I'm going to stick the double sided tape on the side with the dots because it gives us the most surface area for the tape to attach to. Peel one side back, place it on there, press down on it nice and firm, peel the other side off, then we'll stick it to this flat surface here up and out of the way. Press down on it nice and firm to the car. Now we'll take our green wire here. We'll run it on over. We'll make our connections, again male to female, and female to male. Now we'll take our 4-pole flat trailer connector here and we'll route it behind all the other wires first, like so, then we'll route it down behind the carpet panel here where it'll come out here in the spare tire well and be hidden. That way, when we need to use it, we can just pull it out like so to make our connections to our trailer. Now we'll tuck our wire harnesses back behind this panel again. Push our carpet back up behind the panel where it originally was. We'll reinstall our screw. Now we'll do the same on the other side. Now we'll take the couple zip ties that we're included, put them together, and we'll secure a wire to this metal tab here. This will just help hold it in place. We'll do the same on the other side. Now we'll cut off our excess zip tie. Make sure our water stripping goes over it. We'll push down on it until it snaps into place. Once it's snapped in, we can re-secure it with the two torx screws. I'll put our two plastic covers back over. Right here we have a 4-pole flat trailer connector tester. It's part number I26 on our website if you would like to purchase one to test your wiring. We'll just go ahead and plug this in. We'll run through the functions, make sure everything's working right. I'm going to go ahead and turn our headlights on. When I turn our headlights on, the red LED that corresponds to the brown wire on the tester will illuminate. That's working. Now I'm going to turn on our left turn signal. The LED that corresponds to the yellow wire will illuminate. I'm going to do the same for the right. This time it'll be the LED for the green wire. Now when I step on the brakes, both the yellow and green wire, the LEDs that correspond to those, will illuminate solid. As you can see, all of our trailer functions are working properly. Now we're ready to hook up to our trailer. That completes our installation on the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector, part number C56191, on our 2015 Ford Fiesta ST Hatchback.

Customer Reviews

Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - C56191

Average Customer Rating:  5.0 out of 5 stars   (32 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 - no cutting, splicing or tapping required. Converter is made using SMT to ensure superior performance.

- C56191
2014 Ford Fiesta

Very well engineered product and easy to follow instructions come with it.

Excellent, works fine after 1 year.
BWS - 05/29/2021

- C56191
2017 Ford Fiesta

The directions were lacking. It's plug n' play up until the part where you need a drill for the grounding wire. It was here that I searched online and saw etrailer's install video. Well I don't own a drill. Perhaps Curt should include screw specifically for one of those holes in the body that they mention in the directions.

Sorry about the trouble. Sometimes you can drive to an auto parts store and borrow tools right there in the parking lot.
-- Etrailer Expert Sierra K - 09/14/2021

- C56191

worked exactly as expected and come with cable ties and double sided tape to make a clean install. Hides well in the spare tire well under the floor panel and when I use it I just close the hatch on the wiring in a spot where it wont get pinched by the latch.

- C56191
2016 Ford Fiesta

Perfect . Every wire was perfect length . Instructions perfect. Order this and dont look around, If you need to tow with your Fist, Get this and be off sailing.

- C56191

Excellent product and easy to install! Good price and much appreciated customer support. Thanks!

- C56191

Everything about dealing with this company is a five star experience! I called with a really desperate need for a trailer because my family was right in the middle of a move and we needed to tow a trailer. We were down to the final hours and my CSR Debbie jumped through hoops just to get my order shipped at the very last minute of their day. I had to have this trailer hitch so badly that I paid "Next Day Air" to get it. They came through for me!! I got the hitch, it was a big box filled with everything that I needed for my car. And then.......... The movers saw that nice box and packed it away without me noticing and it's now somewhere on its way to Phoenix. I'm towing the car instead!! I still can't believe it! When we finally unpack, I will install it and use it for a bicycle rack which I will buy from etrailer!!! Thanks to all of you at etrailer for really coming through for me!

- C56191

Easy install perfect

- C56191
2018 Ford Fiesta

Product is just as described. This is a great company with excellent customer service. Two thumbs up.

- C56191

Made wiring super easy.

- C56191

Went right on easy install took about 35 minutes nice product perfect fit

Works great easy install no problems of any kind
David - 04/03/2019

- C56191
2016 Ford Fiesta

Quick delivery and good communication from etrailer. Always a pleasure to deal with this company. I've installed trailer wire harnesses in 4 of my previous cars. All of them have been generic harnesses that required soldering. This was the first trailer wire harness install that was completely plug and play. Good instructions and easy to install. About an hour including testing the system and completing a clean install where the wires are hidden and protected.

- C56191

Super easy to install and it comes with everything you need to get the job done. works perfect! 10 min install start to finish.

- C56191
2017 Ford Fiesta

Product worked well. Installation video was a GREAT help and made for an easy install. Would buy products once again from your company.

- C56191

As advertised, easy install, no mistakes, no surprises!

Still working great a year later. No problems, no issues, no surprises.
Big-Rob - 04/03/2020

- C56191

The trailer wiring harness I purchased from etrailer was easy to install and worked as it was supposed to.

- C56191

Excellent service. I will use etrailer again !

- C56191
2016 Ford Fiesta

Great and easy to install

great after one year and lots of use...
Allen & - 08/22/2018

- C56191

Wiring was easy to hook up and works as it should, I am no mechanic and found this to be a breeze to put together!

- C56191
2014 Ford Fiesta

Great product. Fast shipping and the how to videos were outstanding. That's what convinced me to order from etrailer. Outstanding.

- C56191
2019 Ford Fiesta

5 min job!

- C56191
2016 Ford Fiesta

Clear, easy to follow instructions. The unit installs inside the vehicle out of the weather, so it should last and eliminate future wiring issues due to corrosion.

- C56191
2015 Ford Fiesta

Very good instructions (for a change). Installation was simple. Time: Less than an hour for a Ford Fiesta.

- C56191
2017 Ford Fiesta

Love the plug and play wire kits! Work great. Love etrailer!

- C56191

works as described w/o any issues.

- C56191
2017 Ford Fiesta

Easiest trailer wiring ever for me at least took 10mins! I've done many harnesses on lots of different vehicles including vehicles that supposedly had the tow package. This is literally plug and play and go on with your day!

Show More Reviews

Ask the Experts about this Curt Custom Fit Vehicle Wiring

  • Will The Curt Trailer Wiring Harness C56191 Fit a 2019 Fiesta Sedan S
    The Curt T-Connector # C56191 is designed to fit the Hatchback version of 2019 Ford Fiesta, so it will not be the correct fit for your Sedan, However, the Tekonsha T-One Vehicle Wiring Harness with 4-Pole Flat # 118766 is designed specifically for the Sedan versions of 2019 Fiesta and will be the harness I recommend. This will require a wire to be run up to the battery, but will be plug and play the rest of the way.
    view full answer...
  • Recommended Trailer Wiring for 2016 Ford Fiesta
    For your 2016 Ford Fiesta Hatchback, I recommend the Curt T-Connector Vehicle Wiring Harness, # C56191, with 4-Pole Flat Trailer Connector. This connector is your easiest option because it is simply a plug and play harness. There are no wires to run or splice, just quick connects and a grounding ring terminal. It is recommended to use dielectric grease on the connections, like # 11755, to increase the reliability and life of the connection by sealing and preventing corrosion.
    view full answer...
  • Trailer Hitch Fit For 2015 Ford Fiesta ST Hatchback
    The 2015 Ford Fiesta ST is the hatchback model, and there are a pair of trailer hitches that will fit your car, the Draw-Tite Trailer Hitch Receiver # 24961 and Curt Trailer Hitch Receiver # C11067. The accompanying photo is of a hitch on a Fiesta; I have also added a link to an install video so you can see exactly what you'll need to do. The only trimming you'll need to do is a 2" section of the heat shield which means there is no fascia trimming needed at all. Though both hitches...
    view full answer...
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  • Trailer Wiring Recommendation for a 2014 Ford Fiesta Hatchback
    Since the 2014 Ford Fiesta Hatchback has a different taillight setup than the Sedan model you would need to order a wiring harness with a converter built into it like the part # C56191 that you referenced. The # 56047 that you referenced would not be the correct kit for you.
    view full answer...
  • Recommended Class I Trailer Hitch and Wiring Harness for 2017 Ford Fiesta Hatchback
    I recommend going with the Draw-Tite Sportframe Trailer Hitch Receiver – Class I, # 24961, which is confirmed to fit your 2005 Ford Fiesta 5-door hatchback. A major convenience with this hitch is that it does not require the use of stabilizing straps, unlike the otherwise similar Curt model for your vehicle. With a 2,000 lb gross trailer weight capacity and a 200 lb tongue weight capacity, the Draw-Tite model is a very sturdy choice. (Keep in mind, however, that you are always limited by...
    view full answer...

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Info for this part was:

Employee Lindsey S
Written by:
Lindsey S
Employee Laura H
Updated by:
Laura H
Employee Wilson B
Updated by:
Wilson B
Employee Kristina F
Updated by:
Kristina F
Employee Isabelle B
Updated by:
Isabelle B
Employee Cole B
Installed by:
Cole B
Employee Chris R
Video Edited:
Chris R
Employee Zach D
Video by:
Zach D
Employee Brent H
Test Fit:
Brent H

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