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  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 # C56040
Our Price: $33.41
You Save: 44%
Custom Fit Vehicle Wiring

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Shipping Weight: 0.89 lbs
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Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. 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 C56040 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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  • Reviews (2237)
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CURT Custom Fit Vehicle Wiring - C56040

  • 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. 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 - no cutting or splicing of wires
    • Locate connection point in rear cargo area
    • Plug in connector
  • 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 interior trim panel in your rear cargo area. Once you've plugged in the converter, insert the included 10-amp fuse into the integrated fuse holder.

Once installation is complete, the 4-way connector will be stowed in an out-of-the-way location within your cargo area. Adhere the black converter box to the frame of the car using the double-sided tape provided. Secure any loose parts of the T-connector with the provided cable ties.

It is recommended that you use a small amount of grease on all electrical connections - the plug 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.

2010 Subaru with Backup Sensors

56040 CURT T-Connector - Surface Mount Technology - 4 Wire

Installation Details C56040 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 - C56040

Average Customer Rating:  4.8 out of 5 stars   (2236 Customer Reviews)

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

2022 Subaru Forester

It is a really great hitch. And the installation was pretty easy. It only took me about an hour and a good part of that time was spent removing and installing the exhaust system and the worst part was the dust / dirt cover on the driver side of car.

I also bought and installed the trailer wiring harness pigtale . It was very easy once I located the connector on the car. That was hard to find because was not in the normal place for a Forester.


Price was good but the Hitch came torn through the box and the coating removed and even what did not go through the box on delivery was chipped as well. no other packaging was put in the box so the tester and cable harness box could bounce around and move in box. I called customer service to return the hitch due to the damaged coating and they told me to clean it with soap and water and paint it. When I said I did not find that acceptable, she immediate told me that is how they all are and it is from stacking at the warehouse and she offered me a $[XX]paint credit to my card. Be warned! It did install easily by instructions and utube video.

2023 Subaru Crosstrek

Watched the video on the website how to install which made the install very easy. Have yet to test it but looks good and ready to go.

2022 Subaru Forester

Installation went very well. I watched your online video first which was very helpful. Took about three hours because I did it alone in my driveway so had to create ways to hold up hitch while I started installing nuts. Also went slowly so I wouldn't make mistakes. If I had to install another one it would probably take half the time or less with a helper.


Good product. I especially appreciated the video put out by etrailer for the installation. It made it into a simple installation - and the recommendation to keep the harness inside the car unless pulling the trailer was a real bonus, no need to mount on the outside.


The YouTube instructional video helped and made this installation very smooth. perfect fit and it looks great!

2014 Subaru Outback Wagon

Easiest tail light converter that I've ever put on a vehicle Everything went perfect

2023 Subaru Crosstrek

This went in VERY easily and makes for a clean install. Only reason it’s a 4 is that the (tiny) self tapping ground screw stripped out before I got enough torque on it to make a reliable connection (with a human powered screwdriver). I just used a 10 or 12 sheet metal screw that I had in the screw jar. I’d recommend using the provided small screw to drill a pilot hole and then follow up with something bigger. All things considered I recommend this.

2023 Subaru Forester

Would give 5 star if the box wasn't all torn up & slight scuff on hitch. I also got a hitch 2 months ago with the same results. Need to do a better job of packing your stuff. The information & videos as always are great along with the pricing. Don't know if I'll try another place for my next order.

Etrailer Expert

Katrina D.


I am sorry that your hitch arrived with some scuff marks, not only once but twice now. I highly recommend covering up those scuffs with some rust-o-leum type of paint, to prevent any corrosion. As for the poor shipping situation, let me get you over to customer service to see if there is anything we can do to correct this poor experience.

2024 Subaru Outback Wagon

Website was easy to navigate when searching for and ordering a trailer hitch for my new car. checkout was straightforward. Parts arrived quickly. Instructions were clear and succinct.


This is my third time ordering from etrailer. Parts always fit, easy to install if you follow their videos. Would recommend this item, and ordering from this site.

2021 Subaru Crosstrek

Hitch is well built and installed fairly easily by just myself. Another set of hands would be nice when lifting the hitch in place but it's certainly doable. Looks great! Installation videos are a great help.



Fantastic! High quality components and great instructions!


Easy direct fit on my 2016 Outback Limited. Worst part was Subaru made the (male) connector wicked hard to find and get. etrailer's video instruction has the connector just magically "there." Ha. Not so easy. When you remove the left side floor trim support (thin foam piece), the connector will not just be there waving at you. Look for the cargo tie down hook on the left side panel of the hatch, low and just behind the seat back. Under the hook is a cap. Use a flat screwdriver at the top of cap to pry it open, then 10mm socket to remove hook. Stick your finger into the opening in the panel wall where the hook was bolted. The connector is tucked into the space just below that opening, and you have to knock it down a bit, then reach up from the floor behind the panel and drag it out. NOW it'll look like etrailer's video!! It's easy once you know where it is. It's Subaru's fault for tucking it away like that. Not impressed by SUA. But the Curt connector is great


Very easy to install on my '22 Subaru Outback. I didn't bother running it out of the hatch area though. I just pull it from under the mat & hang it out the back when needed. Great!

2023 Subaru Forester

Watching the videos produced by eTrailer make installation a snap. I had the wiring harness installed in about 10 minutes. Keep doing what you do and I'll keep coming back to order!


Wiring kit arrived and looks fine. Have not installed as of this review as E-Trailer is way to fast in asking for a review of the product, but I'm sure it will make the trailer lights work just fine.


Overall easy to install. Purchased the hitch, wiring harness, and fishing wires. Turns out the hitch came with the wires I needed. When I ordered there was a backordered item and they were able to replace it with another to get the order shipped out sooner.


Overall the ordering experience with Stacy was exceptional, as see answered my questions and confirmed my selections. Unfortunately, the wiring harness I originally selected was out of stock. The (#C56040) substitute harness that was recommended did not connect to my 2023 Subaru Crosstrek.

Etrailer Expert

Jenny N.


I know that finding the connector can be tricky to find. We do have a video install that we have done on a 2023 Subaru Outback Wagon that could help.

2014 Subaru Forester

Easy, plug and play install. The support video for this wiring harness was a big help in trim removal and harness location compared to a few other videos I searched for. Key chain style trailer light tester confirms signals are correct.


after installing tn
he wiring my battery
went dead had to pull battery and charge trying to figure out what went wrong will be investigating more. I use another car so it is taking more time, hoping its not the new harness,

Etrailer Expert

Jenny N.


It is a bummer that the battery went dead, however the harness would not be able to cause it. At least I do not know that it can. Were you able to find out what caused the battery to die.

Subaru Outback Wagon

When I bought my used Subaru Outback, it came with an installed trailer hitch, but not a light wiring harness. Installing this harness was easy and went fairly quickly. It tucks away in the spare tire wheel well, and it's easy to access and drape underneath the hatch door when in use.



After a year, it still works great. I simply pull the working end out of the storage well under the bed of my Subaru Outback and feed it under my back hatch. Hook up the end attached to my trailer, and off I go with my boat or utility trailer in tow.


I have put 3 hitches on 3 different vehicles over the past 20 years or so. This was by far the easiest install I have had so far. Everything was simple, lined up under the car perfectly. Heavy duty construction of the hitch makes me feel secure I’ll have worry free use for years. I had the hitch on and wired in less than 30 min. I will certainly buy from here again when I need.


The wiring harnesses work correctly alw ays!!!


Easy to connect, just wish there was a different connection bracket - it didn't fit on the hitch I bought but a zip tie worked just fine


The wiring harness was simple to install and the length of the trailer wiring is perfect.

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