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  1. Custom Fit Vehicle Wiring
  2. CURT
  3. 4 Flat
  4. No Tow Package
  5. Trailer Hitch Wiring
  6. Vehicle End Connector
THIS ITEM IS NOT A FIT FOR
2015 Fiat 500
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CURT

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

Part Number: C38MJ
In Stock
$115.03
Retail:$172.95
You Save: $57.92
Custom Fit Vehicle Wiring
Not Confirmed to Fit

2015 Fiat 500

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etrailer Installation
We'll connect you with nearby partnered installers who know this exact setup.
Easily add a 4-way trailer connector with this custom-fit harness. The T-connector plugs into existing wiring - no cutting needed. Powered converter protects vehicle circuits and ensures consistent trailer lighting for safe towing in any conditions. 1-800-940-8924 to order CURT custom fit vehicle wiring part number C38MJ or order online at etrailer.com. 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 (5)
  • Q & A (0)
  • Videos (2)
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CURT Custom Fit Vehicle Wiring - C38MJ

Highlights

  • Custom Fit for Your Vehicle: Works with your vehicle's wiring
  • Tow Without Factory Prep: 4-way connector powers trailer lights for safe towing.
  • Plug-and-Play Install: T-connectors plug into factory ports—no splicing needed.
  • Protects Vehicle Circuits: Powered converter isolates trailer load from car wiring.
  • Clean, Hidden Setup: Uses existing trim paths for a factory-style install.
  • LED-Compatible Output: Works with standard or LED trailer lighting systems.

Features to know about

Installs Without Cutting or Splicing: Plug-In Harness

Wiring a trailer can be tricky if you have to cut into factory wires. This Curt T-Connector harness makes it simple with plug-and-play connectors that tie directly into the vehicle’s existing wiring. No splicing, crimping, or guesswork—just plug it in and it’s ready for use.

Adds a 4-Flat Connection for Trailer Lights

The built-in 4-pole flat trailer connector gives you the basic lighting functions you need—running lights, turn signals, and brake lights. It’s the standard setup for most small and mid-size trailers, so you can hook up and go with confidence that everything will signal correctly.

Powered Converter Protects Vehicle Electronics

This harness includes a powered converter that draws power directly from the vehicle battery instead of the tail light circuit. That keeps sensitive electronics safe from overload while making sure your trailer lights get full, consistent power every time you tow.

Ready for Vehicles Without a Tow Package

If your vehicle didn’t come with a factory tow package, this harness fills the gap. It provides a reliable connection point at the rear of the vehicle without any extra modules or dealer wiring required. Just plug in the harness and you’re ready to connect your trailer.

Specs

Electrical Specifications

  • Connector type: 4-Pole Flat
  • Powered converter: Yes

Compatibility

  • Installation type: Plug-In
  • Connection type: Plug and Lead
  • Application: Vehicle End Connector
  • Tow package requirement: No Tow Package

56546 CURT T-Connector Vehicle Wiring Harness with 4 Pole Trailer Connector

Similar to Tekonsha TK24VR

Installation Details C38MJ Installation instructions

This Product Fits The Following Vehicles




Video of Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
Video Thumbnail Video Player Dialog

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.




Video Transcript for Review of CURT Custom Fit Vehicle Wiring - T Connector Vehicle Wiring Harness 4 Pole Flat - C38MJ

Hi, everybody, Andy here with etrailer.com. Let's take a real quick look at this CURT T-connector vehicle wiring harness with four-pole flat trailer connector. Now, this harness has been designed to fit your 2021 and newer Ford Mustang Mach-E. And on custom-fit parts such as this harness, I do recommend taking advantage of our vehicle fit guide here at etrailer.com. Simply input the year, make, and model of your vehicle and our fit guide will confirm if this harness will work for you or if we have something comparable that will work for you. So this is going to give you a four-pole flat trailer connector at the back of your Mustang to power your trailer signal lights.

This is going to be compatible with five, six, and seven-pole adapters. Those adapters are sold separately. This does come with a dust cap, as you can see right here to cover up that plug when it's not in use to protect it from moisture, dirt, and debris. So as you know, a well-lit trailer is a safe trailer and this four-way wiring harness is going to keep your trailer's brake lights, turn signals and running lights powered and in sync with your Mustang. Whether you're hauling a boat to the lake or a camper to the mountains, your lights will stay bright and visible.

Now, the custom-fit T-connectors are going to snap into your factory wiring harness. So you're gonna be able to get your trailer lights up and running without cutting or splicing, which is great. You're just gonna plug these connectors in and you're gonna be ready to tow. The vehicle's wiring harness is usually behind a trim panel or under the cargo floor. Some vehicles may require removing interior panels or lifting carpeted sections to reach it.

But once you access it, the harness is going to install easily with these quick splice connectors. The instructions that are included will guide you through the installation process. Now, some vehicles can't handle the extra load of trailer lights, so the built-in powered converter is going to draw power directly from your battery. That's going to ensure a steady, protected current to your trailer while keeping your vehicle circuits from overloading. So this kit comes with everything that you're going to need to get this installed.

You're gonna get a fuse, you're gonna get a fuse holder, butt connectors, cable ties, wiring, and again, as I mentioned, instructions to guide you through that installation process. And it is also recommended that you use a small amount of dielectric grease on all of your electrical connections, like the plugs on your vehicle and the four-pole flat connector itself. So on your screen, I am including the model number of our dielectric grease that we carry here at etrailer.com. You can just take that number and pop it in the search field of our website. That will take you to that grease and you can add that to your order. Again, that grease is designed to help prevent electrical failures that is caused by corrosion and moisture. So it's a great thing to pick up and have on hand. If you do decide that this harness is going to be exactly what you need, we would love to hear back from you after you get this installed. Tell us about the installation process, tell us about how you're gonna be using this, and you can just drop a review on this product page and let us know what you think. And we would also love to see pictures of your towing setup as well and how you're gonna be using this harness. Well, I think that's gonna wrap up our look today. I do hope that our time together has been helpful for you. Again, my name is Andy. Thank you for joining me.

Customer Satisfaction Score:

Ratings & Reviews

4.6

5 reviews
Review sort icon
Easily add a 4-way trailer connector with this custom-fit harness. The T-connector plugs into existing wiring - no cutting needed. Powered converter protects vehicle circuits and ensures consistent trailer lighting for safe towing in any conditions.

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by:

now that it is installed works good



by:

Easy install, very fast shipping


5
5

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

  • Recommended Hitch for a 2024 Ford Mustang Mach-E
    I'd be happy to Dane. To add a hitch to your 2024 Ford Mustang Mach-E, I recommend the Curt item # C77ER. The Curt item # C77ER is a custom fit class III hitch with a 2" receiver. It comes with all hardware necessary to complete the installation and looks great once it's all set up. I really like this hitch because once it's installed all you see is the 2" receiver sticking out below your bumper trim. I attached a couple of pictures below and linked an installation video so you can see...
    view full answer...

Info for this part was:

Employee Lindsey S
Edited by:
Lindsey S
Employee Dustin K
Video Edited:
Dustin K
Employee Wilson B
Updated by:
Wilson B
Employee Katherine B
Updated by:
Katherine B
Employee Andy C
Installed by:
Andy C
Employee Sabrina W
Written by:
Sabrina W
Employee Ethan H
Video by:
Ethan H
Employee Jesse B
Test Fit:
Jesse B

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