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

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

Item # C57672

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C57672 - 4 Flat Curt Wiring
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  • Wiring Adapters
  • Multi-Function Adapter
  • 7 Blade
  • 4 Flat
  • 4 Flat
  • Plug and Lead
  • etrailer
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. Lowest Prices for the best wiring from etrailer. Curt Trailer Connector Adapter - 4-Way to 7-Way RV and 4-Way Flat part number C57672 can be ordered online at or call 800-298-8924 for expert service.

  • All Info
  • Reviews (8)
  • Q & A (3)
  • Videos (1)
  • Photos
  • Why etrailer?

etrailer Wiring - C57672

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.


  • 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


  • 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

C57672 Installation InstructionsInstallation Details C57672 Installation instructions

California residents: click here

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

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

Video Transcript for Curt Wiring - Wiring Adapters - C57672 Review

Today we're taking a look at the Curt 4-pole to 7- and 4-pole adapter. Now this unit adapts a standard 4-way flat connector on your vehicle, to both a 7-way RV, and a 4-way flat connector. So this gives you the convenience of having both connector styles available at the back of your vehicle when you tow a trailer. This is really handy if you're towing different trailers, like you're towing maybe a trailer that just uses a 4-way and then you're switching over to towing a trailer that has a 7-way. This is really nice because now you have both options available at the back of your vehicle.I do want to point out that each connector has a really nice cover that goes over, and keeps the connector clean when they're not in use. And right here's your 4-way.

And then right here is your 7-way. That's a spring loaded lid. Internally, it's got like a rubber gaskets and that creates a nice tight seal when it's not in used. Or excuse me, when it's not in use, and keeps dirt, grime and moisture away from those connection points. The wiring on the back, this is a split loom design, keeps the wires contained and well protected.

And it also comes with hardware, and a metal mounting bracket to secure the wiring connectors to the vehicle or directly to the trailer hitch. Now, your installation is pretty straightforward. This 4-way right, here connects to the 4-way on your vehicle. And then you have four more wires that you need to connect. And then really you're done.Already on the end of each wire is the appropriate connector.

So on these three we have butt connectors. Yellow wire is for auxiliary or backup lights, blue wire is for electric brakes, black wire's for positive power, and then the white wire with the ring terminal on it, that's your ground wire. And that's going to do it for today's look at the Curt 4-pole to 7- and 4-pole adapter.

Customer Reviews

Curt Trailer Connector Adapter - 4-Way to 7-Way RV and 4-Way Flat - C57672

Average Customer Rating:  4.9 out of 5 stars   (8 Customer 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.

- C57672

Works great a easily attached to the draw tite hitch. 655573

- C57672

Great price 652909

- C57672

I'm very satisfied with my trailer wiring purchase. The kit arrived very quickly and is better quality than what I had looked at at the local stores. Information on their website was also helpful with installing the kit. 642981

- C57672

Well built equipment!, just waiting to install it on my Hot Rod dodge, thanks 640139

- C57672

Quick, accurate description and the best price ever. They beat WallyWorld prices. Thanks etrailer! 658805

- C57672

Great quality. Very easy to install. 639245

- C57672

Nicely made and exactly as described ... Thanks 633699

- C57672

Love having both options I have multiple trailers with different plugs so this helps so much. 607039


Ask the Experts about this etrailer Wiring

Do you have a question about this Wiring?

  • How Does 7-Way Trailer Adapter with 4-Way Connector Install
  • What you have pictured is a 4-way to 7-way adapter similar to part # C57672. The male side 4-way connector plugs into a vehicle side (female) 4-way to convert the vehicle's connector to a 7-way. The existing 4-way on the vehicle only has the lighting functions so the rest of the wires need to be hardwired to make the 7-way completely functional. The additional wires are to power reverse lights (yellow), the 12 volt auxiliary pin (black), and electric brakes (blue). The white wire is...
    view full answer...

  • 7-Way Upgrade Kit to Install Curt Echo Brake Controller and Provide 12V Power for Trailer Battery
  • If you have a 4-pole wiring setup now and you want to install a wireless trailer brake controller you will use an adapter like Curt # C57672 or Hopkins # 37185. Both install by plugging in to your 4-pole and by making additional wiring connections using the pigtail leads. If you want to use a wireless smartphone-controlled brake controller like the Curt Echo # C51180 you will not need to run a blue brake output wire. All you'll need to do is provide a 12V power connection to the adapter....
    view full answer...

  • Do the Blue, Yellow, and Black Wires Need To Be Run On the Curt Trailer Connector Adapter C57672
  • For starters, we do not offer products through Amazon as they are a competitor of ours. However, I can offer you the Curt Trailer Connector Adapter part # C57672 which will work on your 1968 Ford F-150 if you have an existing 4-way trailer connector. The additional black, yellow, and blue wires do not need to be attached in order for the trailer light to work but you will need to ground the white wire to your frame. The black wire is to charge a battery on the trailer and you will need...
    view full answer...

Do you have a question about this Wiring?

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Info for this part was:

Edited by:
Lindsey S
Expert Research:
Adam R
Installed by:
Cole B
Written by:
Kristina F

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