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  1. Custom Fit Vehicle Wiring
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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 # C56140
Our Price: $73.73
You Save: 34%
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. Powered converter reduces strain on wiring system and is made using SMT to ensure superior performance. 1-800-940-8924 to order CURT custom fit vehicle wiring part number C56140 or order online at Free expert support on all CURT products. Great prices 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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CURT Custom Fit Vehicle Wiring - C56140

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

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 behind tail lights
    • 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 tail lights. You will have to remove the tail light assemblies 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.

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.

56140 CURT T-Connector Vehicle Wiring Harness with 4 Pole Trailer Connector

Installation Details C56140 Installation instructions

This Product Fits The Following Vehicles

California residents: click here

Customer Satisfaction Score:

Customer Reviews

Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - C56140

Average Customer Rating:  4.7 out of 5 stars   (15 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.

2014 Ford Focus

Black box has something shorting out in it . Trailer lights worked good at first went to Minneapolis and back I problems . One day I come out and my right turn signal on my car is on . I had to unplug the fuse from the power wire to have my turn signals work normal . Hasn't worked right ever since

2013 Ford Focus

Everything is still working as it should...

doesn't matter if it's our Kayak trailer or our small utility trailer the lights always work like the should.

Good easy to follow directions and a reasonably simple install.

Definitely would recommend!


Fantastic service! Quality product, and easy to follow instructions. The installation video really is informative and we'll done. Everything still working great after 1 year. I got a perfect fit,too! The plug end curls perfectly around the hitch and tucks inside it, underneath the car, staying in place and hidden out of sight until needed. A++

Ford Edge

Easy installation, with one exception. To correctly run the wires from the control relay to the light assembly without running them directly beside the rubber - which puts wire on sharp edge steel, instead of through the grommet, I cut the wires, ran them through the grommet and spliced together. This is much better. Curt mfg. should install inline connectors to make this easier.

2013 Ford Focus

The wire harness made it simple to put a trailer connector on my focus and works great for when I need to tow a trailer. I would highly recommend this product.


Easy to install. Could have a better way of getting the inline plugs through the existing grommet easier, i.e. having quick connects so there is no need to cut the grommet. Other then that it was fairly simple to install barring the vehicles interior panels. The pigtail hides nicely under the drivers side rear window where there is an existing hole for access to one of the wing nuts for the tail light.

2014 Ford Focus

Exact fit, all attaching hardware, good instructions, works perfectly!

William J.


All of the products are working as advertised. Had no problems with installation and they all are still working perfectly! Thanks for having such great products and such great prices!Happy New Year !!!!


Easy install if you ever done car wiring. As simple as wiring subs. Didn’t enjoy popping the taillights out but worth it.

2014 Ford Focus

Everything was as advertised. The instructions were easy to follow and all went well.

2015 Ford Focus

With some help from a friend we installed this in 15 minutes, on my 2013 Ford Focus St. All cables and connections have held up well for the year I’ve had it, and I’ve used it a lot. I would recommend this product.


Great product, it's worked well for me for a year.

2012 Ford Focus

I brought this to the ford dealer and had them do it in a jiff! saved a lot with already having what I needed.

2012 Ford Focus

Easy install




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

  • Choosing a Ball Mount for Use with Curt Hitch C11158 on 2014 Ford Focus SE Hatchback
    The Curt Class I trailer hitch you referenced, part # C11158, is indeed a correct choice for your 2014 Ford Focus SE Hatchback. As noted in the linked installation video at the 18-second mark, the top of the receiver opening will be approximately 10-3/4-inches above the ground once installed. With this hitch you will need to use one of the ball mounts recommended by Curt. If you want to use a standard ball mount that allows you to select your own hitch ball you can order part # C45521....
    view full answer...
  • Curt Trailer Wiring Recommendation for 2014 Ford Focus SE
    For your 2014 Ford Focus SE the part # C56138 that you referenced fits the sedan models and the # C56140 fits the hatchback models. There aren't any fit exclusions for either kit due to trim levels. So basically you just need to go with the vehicle style you have and you'll be set.
    view full answer...
  • Can 6-Way Connector with Separate Brake Light and Turn Signal Circuits Install on 2013 Ford Focus
    A 6-Way round connector, especially one that has separate brake light and turn signal circuits, is rare which is why you can't find one. But I can tell you how to make your own 6-Way with separate brake/turn circuits. First, you could get some 6-Wire jacketed wire, # DW04906-1 sold by the foot, and a 6-Way round vehicle side connector such as # HM48420. Then you would use a circuit tester such as # 40376 to find the functions of the taillight wires on your 2013 Ford Focus. Once you have...
    view full answer...
  • Trailer Wiring Harness Options for a 2012 Ford Focus Hatchback
    There are 2 possible wiring harness options for the 2012 Ford Focus Hatchback. You could use Curt wiring harness, # C56140, that you have referenced. The other option is Tow Ready wiring harness # 118549. I have included links to the instructions for both harnesses. Both harnesses install the same way and require a direct connection to the battery to power the trailer lights. This protects the vehicle electronics. The more popular harness is the Tow ready, # 118549, harness.
    view full answer...
  • Installation Video for Trailer Wiring Harness on a 2014 Ford Focus Hatchback
    I have an installation video for you to check out that shows how to install the Tow Ready version of the Curt Harness part # C56140 in a 2012 Focus that is similar to yours. The two harnesses are very similar and would basically install the exact same. I also attached an FAQ on routing the power wire from wiring harnesses for you to check out.
    view full answer...
  • Parts Needed to Tow 2 Seadoos with a 2012 Ford Focus
    My advice would be to bring sunscreen and have a good time! Based on the weight of your trailer and Seadoos you should be fine to use the Curt Hitch part # C11158 on your 2012 Ford Focus to make the trip. You will need a few other components if you don't have them already. You will need trailer wiring for your vehicle, for that I would recommend the part # C56140 if you have a hatchback or part # C56138 if you have a sedan. For a ball mount you would want the part # 3593, for a hitch...
    view full answer...
  • Trailer Hitch Recommendation for a 2012 Ford Focus for Small Trailer
    The Curt hitch part # C11158 has the towing capacities of 2,000 lbs total trailer weight and tongue weight of 200 lbs. As long as the trailer weighs less than that when loaded the HITCH would be okay to tow a trailer. Now you will need to check the owners manual of your 2012 Ford Focus to determine what towing capacities it has and be sure not to exceed this figure either. The lower of the tow ratings will be the overall capacity for the setup. For a ball mount you would want part # C45521,...
    view full answer...
  • Trailer Wiring Harness Recommendation for 2013 Ford Focus SE
    Your 2013 Ford Focus SE comes as a hatchback or a sedan and the trailer wiring harness fits vary for either version. If you have a sedan the kit you want is the Curt part # C56138 or if you have a hatchback you'd want the # C56140. Both of these options are custom fit harnesses that plug inline with the taillight harnesses of the vehicle.
    view full answer...
  • Correct Curt T-Connector for a 2014 Ford Focus ST
    The Curt T-Connector # C56273 that you referenced is not a fit for your 2014 Focus. For your 2014 Ford Focus ST you need the Curt T-Connector # C56140 instead. Since wiring is typically used with towing you will need the trailer hitch # C11431 and then the recommended ball mount # C45521 with the pin and clip # F-4 as well as either a 1-7/8" # A-80 or 2" # A-82 hitch ball. If you plan on using the wiring for lighting on a cargo carrier then please note that Curt requires the stabilizer...
    view full answer...

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

Info for this part was:

Employee Mike L
Expert Research:
Mike L
Employee Michael H
Expert Research:
Michael H
Employee Lindsey S
Updated by:
Lindsey S
Employee Wilson B
Updated by:
Wilson B
Employee Kristina F
Updated by:
Kristina F
Employee Isabelle B
Updated by:
Isabelle B
Employee Jeff D
Installed by:
Jeff D

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