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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 # C56407
Our Price: $71.12
You Save: 33%
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. 1-800-496-5010 to order CURT custom fit vehicle wiring part number C56407 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 (232)
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  • Why etrailer?

CURT Custom Fit Vehicle Wiring - C56407

  • 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 powered tail light converter that connects directly to your battery to avoid overloading your 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: 3.0 amps per circuit
    • Tail lights: 6.0 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 trim access cover, scuff panels, and tail lights to access these connection points. Once you've plugged in the T-connector, run the hot lead to your car battery, which can be found in your trunk on the passenger's side. 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 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.

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.

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.

56407 Curt T-Connector - Surface Mount Technology - 4 Wire

Installation Details C56407 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 - C56407

Average Customer Rating:  4.9 out of 5 stars   (232 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.


Product Review: Fit great. U-tube videos helped. Made a little bracket to hold the coupling. I also bought some wire loam and fished the wires through the frame

2018 Jeep JL Wrangler Unlimited

Maiden voyage with the wiring harness and seven pin adapter and protective loom.
etrailer has the products and associates to back it up. Terrific support, videos and live help if needed. Perfect fit parts. Value and quality can't be beat.

Thank You etrailer.

Flawless. Im going to have a brake controller installed at an RV place. Moving up to a small self contained trailer. I hope that there are no issues at that time.
Peter F - 07/14/2019

2019 Jeep Wrangler

I purchased the hitch and wire harness for my Jeep Wrangler and it fit perfect! I am always nervous about installing anything that requires wiring but the video solved that issue!


Christian is very knowledgeable and helpful. ETrailer products ship quickly and are always the correct items.

2019 Jeep Wrangler

Easy to install. I would have prefered if the t-connector would have been smaller.


I installed this set up about a year ago and everything is working with no problem. This is a great wiring harness and it wasn't difficult to install, I would recommend this product.

Still working fine and I am happy with the product.
Stephen J - 12/19/2021

2018 Jeep JL Wrangler Unlimited

Ordered the receiver wiring harness for my '18 Wangler JL. Been looking for one which isn't a shortcut or over priced. Very impressed with the ordering process and follow through with When the box was delivered, received an email from eTrailer informing me it was delivered. Ran the power wire from the battery to the driver side in the wiring channel located on the back firewall of the Jeep. Drilled a hole in the top plug just large enough for the wire to squeeze through to prevent water creeping in. Then gently wrapped the power wire around the wiring harness to the back tail light, zip tying occasionally. Bonded the control unit (with a little JB weld to help the sticky tape over time). Ran the wires across to the receiver and other tail light. Then connected the battery using the fuse link provided. In total, the effort took 1 hour and 15 min. Kit contained everything I needed. Fantastic experience with


Took some time but otherwise easy to install on my new Wrangler. The instructional videos were a big help when figuring out how to route the power wiring from the rear light up to the battery.


Wire for plugs to passenger tail light on my 2021 wrangler to short. Had to splice in wire extension. Will finish tomorrow to check results.

Routed wiring as per your video. Didnt measure but around 6 to 8 inches.
-- comment by: George - 03/08/2022
I recommend watching the video install that we have on a 2021 Jeep Wrangler Unlimited to see the best way to route the wiring.
-- Etrailer Expert Jenny N - 03/08/2022


Curt products seem to always work well. This isn't the first one I've installed, but the provided instructions should be helpful if it's your first. Well made, easy install. Worst part of job is routing power wire to battery. Should provide years of service.


Love the install you tubes, quality parts and the qualified help from E-Trailer.
Joanne K has always come through for me in a timely manner.

Jeep Wrangler

The trailer hitch and wiring harness that I ordered for my Jeep Wrangler Unlimited fit like a glove. I installed both without any issues at all. The instructions were right on and easy to follow. Shipping was great. I consider eTrailer to be a class act and commend them for a job well done. I will definitely order all my trailer needs from them in the future.

REX D - 07/28/2021

Jeep Wrangler

Worked perfect on my 2020 jeep wrangler.
Easy plug and play installation.


Really awesome product, I had my vehicle wired in 30 minutes. Easy step by step instructions, I looked at the etrailer video and installed the harness. Great quality product, great price and total satisfaction. Return customer for sure.
Thank you etrailer


Super easy to install. The video was fantastic. Thanks


This kit cost way less than the factory mopar harness, I ran the hot wire inside the jeep under the plastic kick panel along the factory harness didn't want it running through the frame very neat, I didn't even have to drill a hole for the ground wire I just put the eye over an existing stud using a metric nut done.the rest was plug & play was a breeze. Thanks George


Very simple installation!


This wiring harness has very easy instructions no problem everything works like it should very good product save me a ton of money dealership said major wire job will be $1000 which was crazy it was a plug and play with one wire running to the front and connecting to the battery


Good product, alittle dificult to install,but worth it . It will allow me to use the jeep to tow my utility trailer. It was much more reasonable than the harness from the jeep dealer.

very well
William - 07/25/2021


Easy to install


Like the product.


This harness I installed on a 2021 Jeep Wrangler JL. I wish the passenger wire for the harness was a little longer. Having said that it works great. Plug and play besides the power wire that has to go all the way to the battery. I ran that along the top passenger frame rail with the other wiring. I recommend it.

2020 Jeep Wrangler

Wiring harness had good directions and was easy to install. Excellent product


Great products and excellent installation information.


Today I installed the harness - took me 2 hours but was EASY. - $93.25 (the one thing I am proud of is that I got so strategic with my wiring that I NEVER used a zip tie :). Also I didnt even have to drill through the firewall. Ran it under the jeep on the drivers side then up through hood and over to battery. I made sure the wires and VERY hidden (I ran them inside of the opening of the rock rails) and away from anything that could get potentially hot.


1. I had to add about 10 inches of wire to the passenger side (used heat shrink connectors).

2. The connector for the battery is too big for the smaller wires. I used a slightly smaller one and worked perfectly.

Its perfect! Would buy it again if I had to in a heartbeat!
Dustin - 07/15/2019

Show More Reviews

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

  • Trailer Wiring Compatible with 2018 Jeep Wrangler Unlimited Sahara Model with LED Light Package
    The Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C56407 is designed for the LED lighting package and will work with your Sahara according to my tech contact at Curt. This harness connects to your factory wiring behind each tail light. Once you've plugged in the T-connector, run the hot lead to your car battery, which can be found in your trunk on the passenger's side. Connect the lead to the included fuse holder, and then connect the fuse holder to the...
    view full answer...
  • Does Wiring Harness on 2018 Jeep Wrangler Need Hot Lead to Battery?
    The T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C56407 that fits your 2018 Jeep Wrangler MUST have a hot lead run to the battery because the port you are referencing is not rated to handle additional amperage. Using this instead of a battery can lead to a fire or fried electrical circuits in your vehicle, so please run the hot lead to your Jeep's battery.
    view full answer...
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  • Will the Curt # C56407 Fit the LED Connectors on a 2018 Jeep JL Wrangler Unlimited Sahara
    Yes, we have confirmed with Curt that the T-Connector # C56407 is compatible with the LED connections on your 2018 Jeep JL Wrangler Unlimited Sahara. Attached is a picture of the connector for the Curt that you can compare to the connector on your JL if you would like. I have also attached a link to the written instructions and a helpful article that explains how to route a 12V power wire to the battery.
    view full answer...
    Image 1 for
  • Wire Gauge of Power Wire for the Curt Trailer Wiring Harness # C56407
    The wire that runs to the vehicle battery that comes with the Curt trailer wiring harness part # C56407 that you referenced is 12 gauge.
    view full answer...
  • 4-Way Harness for 2019 Jeep Wrangler JL Rubicon
    There are wiring harnesses that are designed for your 2019 Jeep Wrangler JL Rubicon, and I recommend the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C56407, which is a confirmed fit for your '19 Jeep without a factory tow package. This harness does in fact plug in to points in your Jeep's rear cargo area, though it does require you to run a hot lead to your battery. This allows the unit to power the converter which protects your wiring, and it is something...
    view full answer...
  • Troubleshooting Tail Light Issue on a 2018 Jeep JL Wrangler Unlimited
    I recommend you check all the connection points on # C56407 on the Jeep side and the new harness side for any bent pins, corrosion, or debris that could be the cause. Bent pins are sometimes the cause of these types of issues since they're so small and may not be making a good connection. If you find any, just gently straighten them out and reconnect the harness and then test again. If this doesn't address your issue, certainly let me know and we can continue the troubleshooting process.
    view full answer...
  • Correct Curt T-Connector Vehicle Wiring Harness for a 2019 Jeep Wrangler JL
    The correct Curt T-Connector Vehicle Wiring Harness for a 2019 Jeep Wrangler is part # C56407 which offers plug-n-play installation.
    view full answer...
  • Trailer Wiring Harness that Fits 2018 Jeep Wrangler
    For your 2018 Jeep Wrangler JL the best trailer wiring kit is the part # C56407. I attached an install video for this for you to check out as well.
    view full answer...
  • Trailer Wiring for 2018 Jeep JL Wrangler Sport Compatibility With Mopar Dinghy Tow Wiring Harness
    The Curt T-Connector Vehicle Wiring Harness # C56407 you asked is compatible with the 2018 Jeep JL Wrangler Sport. It is compatible with any flat tow wiring harness so you can piggy-back with the Mopar dinghy tow wiring harness you asked about.
    view full answer...
  • No Left Turn Signal And Hot Yellow Wire On Curt Trailer Wiring For A 2019 Jeep Wrangler Unlimited
    Installing the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector Item # C56407 on a 2019 Jeep JL Wrangler Unlimited should be straight forward. Due to the plug and play connectors, typically there are very few things that could go wrong. To narrow down the issue you are having, I would start by removing your left tail light. Check the pins on each of the plugs to make sure none are bent. If any are carefully straighten them. Reconnect the plugs and make sure it...
    view full answer...
  • Compatibility of Curt C56407 Trailer Wiring Harness-2021 Jeep Wrangler Unlimited w/ LED Taillights
    According to Curt Manufacturing, their # C56407 trailer wiring harness is compatible with all models of the 2021 Jeep Wrangler Unlimited, so it'll work just fine for you. If you click the provided link, you can see an install video that you might find helpful.
    view full answer...
  • Why Does the Curt Trailer Harness for a 2020 Jeep Wrangler Unlimited Require Battery Connection
    The Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part # C56407 which is a fit for a 2020 Jeep Wrangler Unlimited like most other harnesses will require a connection to the battery. The reason for this is so that it does not pull power from the factory tail light circuits. The factory tail light circuits aren't rated for the additional pull of the trailer lights which is why you need to pull power for the trailer lights directly from the battery.
    view full answer...
  • Best 4-Way Trailer Wiring Kit Recommendation for 2018 Jeep JL Wrangler
    The best choice for 4-way trailer wiring for your 2018 Jeep Wrangler JL is the T-One kit part # 118786. Reason is it has higher amperage ratings so it would be more difficult to short out and because T-One in general just makes more reliable trailer wiring for vehicles.
    view full answer...
  • Why Does Trailer Wiring 2018 Jeep Wrangler JL Need to Run Directly to Vehicle Battery
    Not all vehicles can handle the additional amperage draw of the trailer taillights on the vehicle taillight circuits. Those vehicles need setup that draws power from the battery. Some vehicles have higher rated circuits that can handle this, and others need to have the power drawn straight from the battery to protect the taillight circuits. While it seems easier to just run the power wire to an available accessory circuit it's not the best idea to go that route. In the event of a short...
    view full answer...
  • Will T-One Vehicle Wiring Harness fit 2018 Jeep JL Wrangler Sport S with LED Lights
    Yes, the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118786 is perfectly compatible with LED lights. This harness is a fit and work great on a 2018 Jeep JL Wrangler Sport S without the factory tow package. I have added a link to an installation video of this part for you to check out as well.
    view full answer...
  • Troubleshooting Wiring Harness on 2018 Jeep JL Wrangler Unlimited
    The Dielectric Goo # 11755 is definitely a good idea because it will help prevent your wiring harness from corroding, but if you don't use it that doesn't mean the Curt Wiring Harness # C56407 on your 2018 Jeep JL Wrangler Unlimited should fail. These harnesses do connect to your Jeep's tail lights so one of two things are the likely issue. First, the connections aren't being fully seated into the tail light harness so you will want to double-check that connection. The other potential issue...
    view full answer...
  • Wiring Harness for 2019 Jeep Wrangler Unlimited
    The best trailer lighting harness for your 2019 Jeep Wrangler Unlimited is the Curt T-Connector Wiring Harness # C56407 . This harness comes with a wired power converter to reduce strain on your factory wiring system and the T-one connectors allow for easy installation behind your tail lights. I've linked an install video to this answer that will walk you through the installation of this harness on your 2019 Jeep Wrangler JLU. If you need a ball mount and hitch ball to go with your hitch,...
    view full answer...
  • How to Wire Trailer Connector on Jeep Wrangler for European 7-way
    We don't offer a European 7-way, but I can tell you how to wire one IF the trailer isn't equipped with LED lamps. On the Jeep, you'll take the turn signal and brake lamp inputs and run them through a vehicle to vehicle taillight converter like part # 118158. On the input side of the converter, ground the white wire, attach the green wire to the right turn signal circuit. Attach the yellow wire to the left turn circuit. On the output side, run the red wire to the brake pin on the European...
    view full answer...
    Image 1 for
  • Troubleshooting Blown Fuse on Curt T-Connector Vehicle Wiring Harness
    If you haven't already, I would start by replacing that fuse. The # C56407 uses a 10 amp fuse. I'm assuming you repaired the short in the wiring as well so I would see if it works after the fuse is replaced. If it still doesn't work, it was probably damaged and should be replaced. For a replacement on your 2018 Jeep JL Wrangler I would choose the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118786. When it comes to wiring we have found Tekonsha to be the most reliable...
    view full answer...
  • Curt T-Connector Always Showing Power on Turn Signal of 2019 Jeep Wrangler Unlimited
    I fear the converter of the Curt T-Connector Vehicle Wiring Harness # C56407 has gone bad on your Jeep and you'll have to replace it, but before doing that, there's a couple things to check that hopefully will work out so you don't have to. First, start with the ground wire. You will have grounded it near the converter box, and check that the ground is still good and there's no dirt/rust/corrosion impeding it, and that the wire is okay. A poor ground may have caused a short that is causing...
    view full answer...
  • Recommended Trailer Wiring For 2018 Jeep Wrangler Unlimited Rubicon With Factory Package
    If you the factory tow package with a 7-way you can replace the 7-way with the Curt Trailer Connector for Ford and GM Trucks - Backup Alarm part # C57101 which connects to the towing port on the 2018 Jeep JL Wrangler Unlimited as confirmed by Curt. If you do not have the port you will need Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part # C56407 which plugs in behind the tail lights. This is only a 4-Way though to illuminate the trailer lights so I believe...
    view full answer...
  • Parts Needed to Install 4 way and 5 way Plugs on 2019 Jeep Wrangler Unlimited
    We've got just what you're looking for. You can use the Curt # C56407 to install the 4 way connector on your 2019 Jeep Wrangler Sahara Unlimited, which will give you the 4 way connector. You'll then need to install the Curt Trailer Connector Adapter - 4-Way Flat to 5-Way Flat - Vehicle End # C57187, which can be plugged in when you need to tow the trailer with a 5 way connector. This will plug into the C56407 you've installed and add a connection to the reverse light circuit that will...
    view full answer...
  • Troubleshooting Trailer Wiring Running Lights Not Functioning After Wiring Install
    Sonds like the problem is the trailer wiring kit part # C56407 that you referenced. Typically when this happens if you unplug and replug the connectors of the kit back in the circuit will make the appropriate contact and the circuit will come back on. So what you'll want to do if that does not fix the problem is use a circuit tester like # PTW2993 to test the brown wire that comes off of the connector than runs to the left taillight (one with yellow wire) to see if there is voltage there...
    view full answer...
  • Using C56407 Trailer Wiring w/ TR118821 Taillight Diode System While Flat Towing 2019 Jeep Wrangler
    In order to install the # TR118821, you will need to do a little splicing but the easiest and safest way to do that would be to tap into the wires on the Curt # C56407, the procedure for this is shown in the instructions for the # TR118821, which I've linked for you. Installing in this manner will not harm the trailer wiring harness in any way. I've linked to some videos that you might find helpful.
    view full answer...

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