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Curt Trailer Connector Adapter - 4-Way to 7-Way RV and 4-Way Flat
CURT

Curt Trailer Connector Adapter - 4-Way to 7-Way RV and 4-Way Flat

Part Number: C57672
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$41.09
Retail:$55.05
You Save: 25%
Custom Fit Vehicle Wiring
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This multi-function, vehicle-end connector converts any 4-way flat, vehicle-end plug to a combination 7-way outlet and 4-pole flat outlet. 1-800-940-8924 to order CURT custom fit vehicle wiring part number C57672 or order online at etrailer.com. Free expert support on all CURT products. Great prices and Fastest Shipping for Curt Trailer Connector Adapter - 4-Way to 7-Way RV and 4-Way Flat. Custom Fit Vehicle Wiring reviews from real customers.
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  • Reviews (455)
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CURT Custom Fit Vehicle Wiring - C57672

  • 4 Flat to 4 Flat
  • 4 Flat to 7 Blade
  • Wiring Adapters
  • Universal Fit
  • CURT
  • Plug and Lead

This multi-function, vehicle-end connector converts any 4-way flat, vehicle-end plug to a combination 7-way outlet and 4-pole flat outlet.


Features:

  • Adapts 4-way flat to both 7-way RV and 4-way flat
    • 4-Way flat output connects tail lights, brake lights, and turn signals
    • 7-Way connects tail, brake, reverse, turn signals, and auxiliary power
  • Dust covers keep connectors clean when not in use
  • Split loom keeps wires contained and well protected
  • Simple installation
    • Wiring harness plugs into existing 4-way flat connector and hardwires to existing wiring to get additional functions needed for 7-way
  • Included hardware and metal mounting bracket secures wiring to the vehicle or trailer hitch
  • 1-Year limited warranty


Specs:

  • Distance between bracket mounting holes center to center: 2-1/4"
  • Harness length: 17"
  • Yellow wire is for reverse lights
  • Blue wire is for brakes
  • Black wire is for 12 volt power
  • White wire is ground


57672 Connector Diagram



57672 Curt Multi-Function Socket - 7-Way RV Blade and 4-Way Flat - Universal Fit

Installation Details C57672 Installation instructions


California residents: click here


Customer Satisfaction Score:

Ratings & Reviews

4.7

455 reviews
This multi-function, vehicle-end connector converts any 4-way flat, vehicle-end plug to a combination 7-way outlet and 4-pole flat outlet.

by:

This was very plug and play. As always mounting is usually the tricky part from one install to another from my experience. I was able to mount mine on my Jeeps factory bumper via some larger holes that were in the bottom of the bumper. I used some fender washers an a metal backing plate for my particular install.

Heather A. profile picture
Etrailer Expert

Heather A.

2/19/2025

Hey James! The bracket looks great! The photo really helps other customers if the same Jeep as you. Thanks for taking the time to send it.



by:

I just installed this on my 2015 Volvo XC70. I also used the Curt XC70 plug and Play for wire kit. I watch two of etrailers excellent insulation videos. Installing the hitch and both the wiring products took me around 3.5 hours. I think Curt products are great and they are reasonably priced! e-Trailer makes your DIY installations easy. You just need to take your time when removing interior panels and double check your work. I used Volvo's torque specs for the bumper parts when I installed the hitch. E-trailer doesn't stop with just hitches and wiring solutions, they have just about anything you need to load and haul overhead or behind safely. What about performance? E-trailers got you covered. If you get in a jam during the insulation, don't fret or worry, call the text at e-trailer and they'll walk you through it. I want to thank E trailer and their professional staff for helping me with my truck and auto towing and lighting solution for over 10 years now!

Roger profile picture

Roger

5/9/2025

I love it.



by:

The pictures show the harness 6 months after installation. Due to steep driveways and my wife’s driving; it got bent from its 90° angle. Despite the damage, the harness still works correctly and reliably. 10/10 would buy again…may have to if wife keeps driving.



by:

So far, so good. Haven't installed it yet, but have installed similar one on another vehicle. Have to find good path for the power wire up to the battery.

Robert profile picture

Robert

7/2/2025

After finding good wire path up to engine bay, it went smoothly. Great to have noth 4 and 7 pole connections available.



by:

Easy install. Easy videos to reference. Support knows what they are doing.

Sold etrailer customer for life ??

Victoria H. profile picture
Etrailer Expert

Victoria H.

3/14/2025

Thanks Victor! I'm glad the videos were valuable to you. We enjoy being your go-to!



by:

The connector works as expected and installed easily, but it would be better if there was a better way to store the flat connector instead of having it slide into the bracket from the side.



by:

I used this on my 2017 RAV4. This harness provides me the flexibility of using flat-4 or a 7 way connector for towing flexibility. The RAV4 is a small tow vehicle and I like the added security of electric brakes even on lighter single axle trailers which the 7 way allows. I plugged this adapter into the flat-4 connector provided by the "T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector Item # 118578" and used heat shrink tubing around the crimp connectors for the brake controller wires to keep moisture out.



by:

Informative,patient, and knowledgeable. Good company to do business with.



by:

I mounted this on our travel trailer so I could use a 4 pin flat plug to connect to the tow vehicle. Works great



by:

I’m very happy with the help I received from E-trailer but I wished that I was told that I would need 10 gauge wire for the E150 van I was working on. Believe it or not it was very difficult to find 10 gauge wire that is double jacketed. It would have been a bigger sale if you added twenty feet of your wire and I would not have needed to spend the time to get the wire.



by:

Needed to slightly modify the bracket clearance holes to have the plastic holes line up properly and fit cleanly. Not a big deal but someone else may have struggled with that if they expected a simple install.



by:

Easy to install. Works great!



by:

This was/is a critical piece of any towing system, and as such requires extra care to hook up properly . I would recommend testing each connection as you hook it up being extra careful to make sure you are matching the terminals in the mating connector properly. This harness/connector performs perfectly when properly installed.



by:

Worked great for me. Ran my own wiring. In retrospect I would just order the kit from Mopar but this did the trick!



by:

Nearly plug and play. Makes for easy wire identification and installation.



by:

Good product easy to install only reason for 4 stars is that the 4 pin connector doesn’t stay in the provided slot on the bracket



by:

Your site us very helpfull for information and support and i reallt apreciate etrailer for all tge purpose.good product ,help support,and fait delivery even heure in Canada.
Tgank to all of your team.i am presently installons the controller on my car after the installation i Will feed about how it work.
Have a nice day

Luc profile picture

Luc

7/30/2023

Very well great product,goid brake controll ,smooth,ibreally like the way it work,and Allo it take juste à small place under dash for me 10 star a grest product

Luc profile picture

Luc

7/30/2023

Great product the curt7pin with the 4 pin on the side really helpfull for installation good product ,to be sure keeping moisture away in the connector i Also use electric compound grease in it to prevent corrosion and still very good no connection problem yet even with the kind of weather we have here up North in Quebe crain ,snow,..good product well made.



by:

Turned out I didn't need this part. Was surprised at the charge billed for the return. Seemed high.



by:

Good product overall, installed on my 2016 Volkswagen Golf to tow a 13' Scamp fiberglass trailer. Although do be attentive, as other reviews have stated, that using all the functions of the 7-pin connector (electric brakes on the trailer) may require extra work. In my case, it required running an extra lead from the car battery with a fuse in line. I was was able to run it through the body of the vehicle, although I gather it's also possible to run it under the entire vehicle. Just something to be aware of; as my first time towing anything, it was a learning curve to understand how to put it all together.



by:

This would be a 5 star rating if all my trailer plugs fit equally well. The preformed trailer wiring plugs are a perfect fit, (4 out of my 6 trailers have them), but two aftermarket plugs are a struggle to get the retention notch to fit inside cover hook that keeps the plug in place. ((Otherwise the plug pops out)).
Bottom line is I would buy this connector again because of the price point and ease of installation. From now on I will be buying the preformed trailer wiring harness for the perfect fit.



by:

This product worked great for me. I had a little trouble fitting it to my Toyota Sienna (it would have helped if the 4 pin flat connector could be located on either side of the 7 pin round connector), but functionally I’ve had no issues. One weakness I could see is the included butt connectors are not heat shrink type so they’re not weatherproof. This could lead to corrosion in the wiring eventually. Otherwise good product!



by:

Overall, satisfied. The installation videos were helpful, and the product seems quality. I only have one complaint, which is what kept this from being a 5 star review. This may be obvious to most people, but it wasn't to me. This WILL get you to a 7 pin connector, but there is a good bit more work to do to get all the functions of a 7 pin connector to work. Meaning, to get power to my 7 pin connector and trailer, I had to run a wire to the battery, and place a circuit breaker inline with that wire. Again, this may seem obvious to some, but it took some figuring out for me, and any time I asked this question to etrailer, they could never seem to give a straightforward answer. But for my Mazda CX-5, about 15 feet of 12 gauge wiring and a small fuse kit did the trick. Lots of splicing of course.



by:

Put this on after #c56027 to change to 7-way rv plug as all my trailers have been switched to 7-way. 7-way is much easier to plug and unplug than 4-way. Easy to install. I have been using it once a week and it is working very well.



by:

I took my car over to the dealership and they sent it out to another shop. When he brought my car back, the electrical wires were installed upside down. It took the installer over 6 hours to install my receiver hitch.
It looks great now that I’ve turned the wiring the correct way to install your electrical wiring.



by:

Installed it myself and towed my camper from NC to Cali with it! Worked great and held up the whole time!


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