bing tracking image
  1. Custom Fit Vehicle Wiring
  2. CURT
  3. Custom Fit
  4. Trailer Hitch Wiring
  5. 4 Flat
  6. Powered Converter
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 # C56138
Our Price: $64.64
You Save: 22%
Custom Fit Vehicle Wiring

Will this fit?

To see if this custom-fit item will work for you please tell us what vehicle you'll use it with.

This item qualifies for Free Shipping
Shipping Weight: 1.75 lbs
In Stock
zoom in icon
slider vertical icon
zoom out icon
Comment field cannot be left empty.
Name field cannot be left empty.

Thank you! Your comment has been submitted successfully. You should be able to view your question/comment here within a few days.

Error submitting comment. Please try again momentarily.

Product Images

In Use/Installed


Need help with installation?
Locate installers near me
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. 1-833-496-1390 to order CURT custom fit vehicle wiring part number C56138 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.
  • All Info
  • Reviews (15)
  • Q & A (0)
  • Photos
  • Why etrailer?

CURT Custom Fit Vehicle Wiring - C56138

  • 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.

56138 CURT T-Connector - Surface Mount Technology - 4 Wire

Installation Details C56138 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 - C56138

Average Customer Rating:  5.0 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

This was an easy install. I took my time on a lazy Saturday and it only took about 35 minutes. The only thing I would recommend is a weather proof splice connector under the hood for connecting the fuse holder. I was able to put it inside the battery box of my 2014 Ford Focus SE so it should be somewhat protected.

one year later and its still working great!
William F - 12/15/2021

2018 Ford Focus

This is a high quality wiring kit which I installed on my 2018 Ford Focus sedan. The most difficult part of the installation was removing and reinstalling the trim pieces inside the vehicle's trunk, which were more complicated than my 2013 Focus hatchback. The wiring and connectors seem to be high quality and the trailer lights work perfectly. To avoid putting a wire through the dash panel to the battery in the engine compartment, I used an "Add-A-Circuit" kit from my local auto parts store to power the lights from an unused circuit in my vehicle's fusebox.

Curt, the manufacturer recommends installing the power feed directly to the positive battery terminal. Drawing the power directly from the battery isolates the tow vehicles sensitive electronics from any short circuits that might occur in the trailer wiring. Connecting the converters power feed anywhere other than the battery or where the converters manufacturer recommends can leave your vehicles electrical system exposed to possible damage.
-- Etrailer Expert Mike L - 09/11/2018
Still working great after one year
Thomas - 09/11/2019

2012 Ford Focus

took little to no time to install I would recommend this product.


It fits and works well. Good product.


it was not simple to pull, but i did and it works, also ground on the contact might be helofull for something like back up camera

Nadezda U - 04/07/2021


Got some shop near me to install it for 60 bucks because that was cheaper than the tools I'd need to buy to install it. Easily pulling a 4x8' trailer with my 2014 ford focus. Pulled a metal [trailer] 5x10' with an upright grand piano weighing around 800 lbs. and the hitch didn't come loose so that's good

2015 Ford Focus

I just got my Class I hitch for a 2015 Ford Focus today from UPS. Dang fast order and excellent packaging. Easy to follow directions. I took my time during the install, i.e. putting it up and down a couple of times. Really easy and all holes lined up. Nifty "tool" provided for getting the top bolt and washer in the hole, otherwise I think I would have taken out my welder. I also ordered the trailer connection kit. Man, that took no time at all. I am very happy with this product. Oh yeah, one more thing. No job is complete unless you leave a DNA sample behind. I did.


The wiring harness was real simple just unplug and plug in new wiring harness with the car harness


there was a fuse box in trunk so I didnt have to run wire under car


Third one I have installed. Works just like it should and directions are straightforward.

2013 Ford Focus

Very easy to install. No wire splicing. All plug and play. Video instructions if needed.

2014 Ford Focus

very fast delivery, I just dislocated my shoulder, so it will be at least 6 weeks before I can install, but everything looks to be as advertised.

2014 Ford Focus

Awesome product. Easy to install with minimal tools. The directions were spot on!! Thank you

2014 Ford Focus


Great product. Great vendor


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

  • Trailer Wiring Harness for 2016 Ford Focus Sedan
    Curt 4-pole wiring harness # C56138 is the correct part for the 2016 Ford Focus Sedan and will provide basic trailer lighting functions. If you have the hatchback version then instead use part # 118674. Both plug in at your tail lights as shown in the linked video. El arnés de cables de 4 polos Curt # C56138 es la pieza correcta para el Ford Focus Sedan 2016 y proporcionará las funciones básicas de iluminación del remolque. Si tiene la versión hatchback, utilice la pieza n. ° 118674. Ambas...
    view full answer...
  • Trailer Running Lights Lit All the Time w/Curt Trailer Wiring Harness Installed in 2013 Ford Focus
    Does your trailer happen to have LED lights? If so then what is happening is the little bit of power that is on wiring harness # C56138 is enough to dimly light up LED lights. This is because the wiring harness is a powered harness and LED lights draw such little power. We hear about this issue less with the Tekonsha harness # 118548. It is also possible that there is a short drawing power. Make sure the trailer connectors are clean and free of corrosion. Also check the wiring on the trailer...
    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...
  • Troubleshooting Trailer Wiring Where Running Lights and Blinker Dont Work
    It's very possible the trailer connector dragging on the road could have caused a short once you fixed the wiring. It really depends though on if the wiring was damaged as well and if the connector was attempted to be plugged in. First thing you should do at this point is test the 4-way of the wiring harness with a circuit tester part # PTW2993 for voltage on all of the right pins when the taillight signals are being applied. Just like in the video I attached. If the voltage checks out...
    view full answer...
  • Length of Power Cord on the Roadmaster EvenBrake Supplemental Braking System
    The length of the power cord for the Roadmaster Even Brake part # RM-9400 is 42 inches. The power cord plugs into a cigarette lighter type socket and draws a max of 10.8 amps. The cable would need to be an extension using connectors like that and capable of handling 11 amps.
    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...
  • 4-Pole Trailer Wiring Harness for 2016 Ford Focus Hatchback
    If your 2016 Ford Focus Hatchback is the ST model you can use the Curt 4-pole wiring harness kit # C56273. This kit include custom-fit connectors to allow plug-in installation at your taillights. The only wire to be spliced is the 12V power wire; an article is included to assist you in routing that one wire. If you have one of the other hatchback versions - the S, SE or Titanium - then instead you can use Tow Ready kit # 119190KIT. This kit does not have the custom-fit connectors so its...
    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 Draw Tite Hitch part # 24872 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...
  • Can a 2012 Ford Focus Tow a 600 lbs Total Jon Boat?
    According to your owners manual, your 2012 Ford Focus should never tow a trailer and is not equipped to tow. Using a trailer hitch like # C11158 is ideally to be used for accessories like a bike rack. Your vehicle has a payload rating between 935 and 1,055 lbs so if somehow you fit it inside your vehicle Ford would be okay with it. I personally would tow that trailer (but not anything larger than the jon boat) and you would be operating outside of Ford's warranty and recommendation. Based...
    view full answer...
  • Trailer Hitch and Wiring Recommendation for a 2012 Ford Focus
    The Curt trailer hitch part # C11158 that has been confirmed as a fit for your 2012 Ford Focus does not come with trailer wiring but you can order it separately with part # C56138. For a ball mount you would want part # C45521, 2 inch hitch ball part # A-82, and 1-7/8 inch ball # A-80. I attached an install video for the hitch for you to check out as well.
    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...

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

  • Why

    At we guarantee:
  • Real product know-how.

    We make sure that the products we sell are what we say they are, and that they work the way they are supposed to work. Get real advice from a real person who has the knowledge and expertise needed to solve your problem.
  • Most detailed, accurate custom fit vehicle wiring information available.

    Because we take providing accurate product information seriously, we take our own detailed product photos, demo videos and installation videos, as well as verify measurements, instructions, and vehicle fit information.
  • Installations, made easy.

    We love helping people and have the most highly-trained customer service, hands-on experience, step by step videos and installation instructions.
  • Fast shipping.

    Your order is automatically routed to get out of our warehouse and to your door as quickly as possible. Receive free shipping on orders over $99.
  • Personalized service for life.

    We provide one-on-one, personalized service from the ordering process through the life of your product.
  • Trusted since 1946.

    We've been serving customers since our parts store first opened in 1946 and continue to be recognized by our customers, our vendors and third parties for exceptional service.
  • Returns Policy

    Need to return an item? No problem. Please read our Returns Policy for more information.

Info for this part was:

Employee Michael H
Expert Research:
Michael H
Employee Jameson C
Expert Research:
Jameson C
Employee Adam R
Expert Research:
Adam R
Employee Chris R
Video Edited:
Chris R
Employee Wilson B
Updated by:
Wilson B
Employee Kristina F
Updated by:
Kristina F
Employee Isabelle B
Updated by:
Isabelle B
Employee Brent H
Test Fit:
Brent H

At we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time. Let us know if anything is missing or if you have any questions.

Product Experts Available Now!
Call 1-833-496-1390