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

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

Item # C57102
Our Price: $38.20
Trailer Wiring
Shipping Weight: 1.37 lbs
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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. Features an integrated backup alarm. Great Prices for the best trailer wiring from CURT. Curt Trailer Connector Adapter with Backup Alarm - 4-Way to 7-Way RV and 4-Way Flat part number C57102 can be ordered online at or call 1-800-940-8924 for expert service.
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  • Reviews (55)
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CURT Trailer Wiring - C57102

  • Wiring Adapters
  • Multi-Function Adapter
  • 4 Flat
  • 7 Round - Blade
  • Plug Only
  • 4 Flat
  • CURT

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 an integrated backup alarm.


  • Connects to 4-way flat plug on your vehicle
    • Requires additional wiring for use of brake, power and accessory leads
  • Supplies 7-blade RV and 4-wire flat trailer connections
  • Sounds alarm when vehicle is in reverse
  • Constructed of durable plastic


  • Yellow wire is for reverse lights
  • Blue wire is for brakes
  • Black wire is for 12 volt power
  • White wire is ground
  • 4-Way connector plugs into vehicle 4-way connector

57102 Curt Multi-Function Socket with Back Up Alarm - 7-Way RV Blade and 4-Way Flat - Universal Fit

Installation Details C57102 Installation instructions

California residents: click here

Video of Curt Trailer Connector Adapter with Backup Alarm - 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 - C57102 Review

Man: Today we're going to be taking a look at Part Number C57102. This is a Curt Trailer Connector Adapter with a backup alarm. This is 4-way, the 7-way round and 4-way flat. The multi-function vehicle end connector is going to convert any 4-way flat connector vehicle end plug to a combination of a 7-way outlet which is going to be this portion right here. And a 4-pole flat outlet. It's also going to feature the integrated backup alarm and it's going to have three LED lights on there as well. This is designed to connect to a 4-way flat plug on your vehicle.

You're going to have the connection right here to make that appropriate connection. It is going to require additional wiring for the use of brake, power, and accessory leads. All of the brake or . excuse me. All the wires here included in the harness or the adapter are going to have the appropriate connectors on here.

You're going to have three of them that are going to have the butt connectors and then the white is going to be your ground and that's going to have the ring terminal on there that will need be attached with a self-tapping screw. So again this is going to supply your 7-blade RV connector right here as well as a 4-way flat trailer connector. It's going to have the nice dust cap that goes over the connection points to prevent them from any type of corrosion. And then on the 7-way connector it's got the nice spring loaded lid that's going to protect the connection points as well. Now this is going to be constructed of a durable plastic construction. It's going to come with a mounting bracket and the necessary hardware to mount the connector to the actual bracket. You will need the hardware to mount the bracket to the vehicle, that is going to be sold separately.

Through these holes right here that's going to connect using two number 10 half inch self-tapping screws. You can also use a number 10 half inch self-tapping screw to mount the ground connection with the ring terminal here on the end of the white wire. Now to go over the wire functions real fast with you, the yellow wire is going to be for the reverse lights. Your blue wire is going to be for the brakes. The black wire is going to be for 12 volt power and then your white wire is going to be for your ground connection and then you're going to have the four way connector that's going to plug into the existing vehicle 4-way connector. Once you have all those connections made, you're going to have full use of your 7-way connector right here as well as the 4-way flat connector right here. I'm going to show you how it mounts with the bracket.

Just run all the wiring through the slots there, feed your 4-way flat through there as well. Now the holes in the bracket are going to line up perfectly with the holes here on national connector. Now that's going to be able to mount to the rear of your vehicle. It's going to hold it place and you have a little area here on the side of the bracket for your 4-way connector as well so it's going to stay right there next to the 7-way connector. That bracket is going to hold it in place. So real quick I just want to go ahead and show you the function here of the backup alarm. I'm going to go on and make our necessary connections and then you can see how that operates. Sends out a nice strong signal. It's really loud. You'll be able to see the lights flash as well. I'm going to activate the reverse function (beeping sound). That's going to sound and flash anytime the reverse function is activated on your vehicle. That's going to do it for today's review of Part Number C57102. This is the Curt Trailer Connector Adapter with the built in backup alarm. .

Customer Satisfaction Score:

Customer Reviews

Curt Trailer Connector Adapter with Backup Alarm - 4-Way to 7-Way RV and 4-Way Flat - C57102

Average Customer Rating:  4.8 out of 5 stars   (55 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. Features an integrated backup alarm.


Exactly what I was looking for. Easily connected to my existing 4-way without any additional wiring. The 7-way adapter bracket was the correct size, and the holes were pre-drilled for the right fit to connect to the existing bracket on the (U-Haul Installed) tow bar.


Just received the 4-way to 7-way adapter and it is everything I had hoped it would be. Shipping was extremely fast and it arrived when you said it would. Thank you.

Charles Stanley


Installed perfect .. love it

Jeffery - 03/19/2023


Product is great. Guy on phone made it sound super simple. Now I have to go get the additional pieces and wires to hard wire it in…thought the phone rep should have been more thorough. “Oh, c’mon Jim. Don’t be afraid.” He said nothing about splicing, running wires, circuit breaker or anything.

Sorry about that! This product uses at least 12 gauge wire and butt-connectors to connect the wires to the appropriate functions. Most of the time the colors are in this order but you may have to confirm the function with a circuit tester. Yellow for auxiliary or back-up lights, blue for electric brakes, white for ground, and black for positive power. If you do not need some of the functions, you can secure the wires up using cable ties.
-- Etrailer Expert Sierra K - 07/07/2022


good product.


Easy installation


very well built, easy to install. made converting from 4 wire flat connector to 7 wire round an easy process.
I will use the 12 volt battery and the backup wire ,don't need the brake wire.


Good product and install instructions.
only complaint is the 4 pin connector falls out of the housing.


Just what I needed, easy to install. Excellent instructions. Good quality at a good price. etrailer, my go to place for everything "trailer/towing", Not my first purchase. Don't spend too much time shopping around, you'll be frustrated with the wasted time. Thanks


Great product....easy wiring and flawlessly


LOVE/LOVE/LOVE "this" particular model= it has a "beep" warning alarm noise system when you are backing up! IT ALERTS! YOU-LOUD! AWESOME/much needed upgrade from what came with my vehicle.


Its working great pulling my Aliner with my Kia Sportage.
Carlos - 08/27/2022


Installed and seems to work fine. Will put it to the test next spring.


very satisfied


It fit perfect, and we pulled our camper to California from Ohio and back, no problems.


I like what I see but unable to give an accurate review because I don't have it installed on my vehicle yet since I just got it this afternoon and had other projects in the process at the moment.


Not an Easy hookup for my new Rubicon as stated.


Great product for the price not to mention hella easy hook up thanks holly recommended


My son got it on and works great. Fast service. Can not complain.




Great high quality at a very reasonable price .


Love it



Product exactly as described. Shipped fast and in good condition.


Show More Reviews

See what our Experts say about this CURT Trailer Wiring

  • How Does the Curt Connector # C57102 Wire Up
    After you plug the 4-way in from your 2006 Ford E-350 to the Curt Trailer Connector Adapter # C57102 you will need to run the rest of the wires as follows: The white wire will need to be grounded to a clean metal surface. The blue wire will go to the brake output signal of your brake controller. The black wire will go to the positive side of your battery through a 40 amp circuit breaker like part # PK54540 The yellow wire will run to the reverse light circuit.
    view full answer...
  • Installation of the Curt Trailer Connector and Back-Up Alarm # C57102 on a 2001 Jeep Grand Cherokee
    Yes, you can connect the yellow wire of the Curt Trailer Connector and Back-up Alarm, # C57102, to the back-up light circuit on your 2001 Jeep Grand Cherokee. Connecting the yellow wire will allow the back-up alarm to activate when you put your Jeep in reverse.
    view full answer...
  • Does the Backup Alarm on Curter Trailer Connector Adapter # C57102 Sound Just when Towing
    Any time the vehicle is placed in reverse, whether you are towing or not, the alarm will sound. You will have to make sure that yellow wire is connected to a reverse light wire on the vehicle in order for the alarm to function.
    view full answer...
  • What are the Wire Functions of the CURT Trailer Connector Adapter, # C57102
    You are correct. On the CURT Trailer Connector Adapter, # C57102, the white wire is ground, black is for 12 volt power, blue is for brakes, and yellow is for reverse lights. The 4-Way would then just plug into a 4-Way trailer connector on the vehicle to provide the remainder of the lighting functions. Be sure to ground the white wire to the vehicle frame for the connector to function properly.
    view full answer...
  • Does Brake Controller Installed on Trailer Require Blue Wire to Be Connected on Tow Vehicle
    Since your trailer already has a brake controller on it you shouldn't need to connect the blue wire from the Curt Trailer Connector Adapter with Backup Alarm # C57102 so you should be able to just cap it off and be fine. I say "should" because any brake controller I've seen that installs on the trailer only requires the standard light functions along with the 12V power. If you can confirm what brake controller you have then I can double check the installation.
    view full answer...
  • Installing a 7 way Plug On An Australian 1998 Land Rover Discovery
    I do have a potential solution for you. Unfortunately we do not offer any kind of custom wiring kits or adapters you can use for this purpose. What you can do is remove the 7 pin flat plug and splice in a 7 way round plug like the # C57102. In order to separate out the turn signals from the brake lights you would need a converter, # 118158.
    view full answer...
  • Universal Version of the Curt Trailer Connector # C57101
    The closest thing we have to a universal version of the Curt Trailer Connector # C57101 would be the Curt Trailer Connector Adapter # C57102. This adapter is designed to plug into a 4-way and then the other 4 wires would get run to where they belong. White to ground Blue to brake controller output Yellow to reverse light circuit Black to positive side of the battery
    view full answer...
  • What Circuits Of The 7-Way Blade Connector Are Required To Use a Curt Echo Trailer Brake Connector?
    A reverse circuit wire is not required for the Curt Echo Wireless Trailer Brake Controller # C51180 to operate correctly. It only needs to get power form the charge line/auxiliary circuit of the 7-way and see signal from the brake lights (the brake lights are a combination of the left and right turn signals operating at the same time, because of this do not use your hazard lights with a Curt Echo installed). Your trailer will only require that the reverse lights portion of the Curt Trailer...
    view full answer...
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  • Does the Alarm Always Sound in Reverse on the Curt Trailer Connector Adapter with Backup Alarm?
    Any time your vehicle is placed in reverse, whether you are towing or not, the alarm will sound on the Curt Trailer Connector Adapter with Backup Alarm item # C57102. To have the same connector without the beeping sound you will want the Curt Trailer Connector Adapter item # C57672. This is the same 7-way and 4-way connector without the alarm. I have linked an installation video below.
    view full answer...
  • Where to Tap Into Reverse Light Circuit to Install Trailer Connector Adapter with Backup Alarm
    To wire in the reverse light wire on Curt 7-Way connector # C57102 for the back up alarm to work you will need to tap into a reverse light wire behind a reverse light on your 1999 Dodge Ram. If you do not wish to tap into the wire there then you can trace the harness to a more accessible location. Then use a circuit tester such as # PTW2991, to find the correct wire before tapping into it. Be sure that the white ground wire on the 7-Way is attached to the truck frame. Otherwise the harness...
    view full answer...
  • How To Attach A Brake Controller To My 1999 Dodge Dakota Sport V4
    The Curt Trailer Connector Adapter with Backup Alarm # C57102 will work when setting up for a brake controller but you will also need to purchase The Wiring Kit for 2, 4, 6, and 8 Brake Electric Trailer Brake Controllers # 5506. This kit includes all the additional wiring you would need to make The Curt Adapter # C57102 to run the brakes on your trailer. For your brake controller I recommend the Tekonsha Prodigy P3 # 90195. This fully proportional controller has an easy-to-read LED display...
    view full answer...
  • What is the Blue Wire on the Curt C57102 7-way Connector with Backup Alarm Used For
    The blue wire on the Curt Trailer Connector Adapter with Backup Alarm - 4-Way to 7-Way RV and 4-Way Flat # C57102 is designed to be connected to the brake controller in your 2019 Jeep Grand Cherokee. If your Grand Cherokee didn't come with the factory tow package and you're needing to use a brake controller then you will need run a wire from the blue wire on the back of the 7 way up to the engine compartment and through the firewall into the cab of the vehicle. Once it's run through the...
    view full answer...
  • Could 4-Way to 7-Way Adapter with Reverse Alarm Fit 2020 Honda Odyssey with 4-Way
    Yes if you wanted to use the # C57102 as a way to convert your 4-way to a 7-way and install the brake controller you mentioned. You will need wiring to run from the brake output of your brake controller to the blue wire of this adapter. We have 10 gauge wire for this with # 10-1-1 which we sell by the foot.
    view full answer...
  • Parts Needed to Install a Brake Controller and 7-Way in a 2012 Lincoln Navigator
    Yes, the Curt Trailer Connector Adapter # C57102 would be the correct part for you to use to convert your 4-way to a fully functional 7-way. You would just need to run the wires of the # C57102 to those leads. If there isn't a 12 volt power lead you will need to run a 10 gauge wire like part # 10-1-1 through a 40 amp circuit breaker like part # 9510. The brake controller we recommend the most is the Prodigy P2 Brake Controller part # 90885. This is the best selling controller on the market...
    view full answer...
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  • Trailer Wiring For A 2022 Nissan Frontier
    Although The Hopkins Plug-In Simple Vehicle Wiring Harness # HM43534 is not confirmed to fit your 2022 Nissan Frontier we do have the parts you will need! The Curt Vehicle Wiring Harness # C56225 will give you a 4 flat connector and will plug into your vehicle's wiring harness which is located beneath the rear of the vehicle, along the driver's-side frame rail. After the 4-flat connector is installed you will need The Curt Trailer Connector Adapter with Backup Alarm # C57102 will attach...
    view full answer...
  • Will the the Hopkins Back Up Alarm Fit both a Ford 2009 F-150 as well as a Ford 2013 F-150
    I have checked with my contact at Hopkins, and it looks like both the 2009 and 2013 Ford F-150 use a 921 bulb. Hopkins does not currently have a back up alarm system that is compatible with this tail light bulb style. If you would like you could use the Curt # C57102 or the #C57101. These are replacment trailer connectors that have also have a back up alarm included. If your trucks currently have a factory installed 7-way you will want to use the # C57101 as a direct replacement. If not...
    view full answer...
  • Recommended Wiring Harness For A 2022 Volkswagen ID 4
    Though we do not have a custom wiring kit for your 2022 Volkswagen ID 4, you can use the Curt Powered tail light converter # C59236 that will provide you with a 4-flat harness. To get the 7-way round you will need to install the Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat # ETBC7. Both harnesses mentioned are spliced in wiring. This is the only option that we have to get you a 7-way plug on your Volkswagen. You could also contact the dealership directly...
    view full answer...
  • How To Get A 7-Way and 4-Way Trailer Connector On A 2012 Ford F150 With Only a Factory 4-Flat
    If under your rear bumper you have in addition to the 4-pole flat connector additional unterminated wiring for a 7-way you can use Curt # C57102 to convert your Ford F-150 4-pole flat trailer connector to a combination 4-pole and 7-pole trailer connector. This part includes the additional feature of a backup alarm, which is activated simply by connecting the yellow wire to the reverse light circuit, if desired. The alarm will sound when the F-150 is shifted into reverse gear. If you prefer...
    view full answer...
  • Parts Needed to Add 7-Way and Brake Controller on 2017 Subaru Outback Wagon
    In order to install a fully functional 4- and 7-Way connector on your 2017 Subaru Outback Wagon you will need to start with a 4-Way harness if you don't already have one. For this I recommend the Tekonsha T-One Vehicle Wiring Harness # 118467. This custom harness will simply plug into factory ports located in the rear cargo area on the Outback. I have attached an installation video that you can use for reference. Then with the 4-Way installed (or if you already have one on the vehicle)...
    view full answer...
    Image 1 for
  • Add 7-Pin to 2022 Hyundai Palisade with Factory Tow-Package
    Use the Curt T-Connector Vehicle Wiring Harness for Factory Tow Package, # C68JR to quickly and easily install a 7-way, RV-style trailer connector on your 2022 Hyundai Palisade. This is a plug-n-play install but I do highly recommend, to keep the connector safe from corrosion and moisture you use a Dielectric Grease such as, # 11755. For a brake controller, I suggest the Curt Echo Wireless Trailer Brake Controller, # C51180 for 1 to 2 axles. Once the Echo is installed, it will sense -...
    view full answer...
  • Does Curt Echo Brake Controller Need to be Level with Ground
    The Curt Echo Brake Controller # C51180 referenced in your question does not need to be at any particular angle in relation to the ground for proper operation. The controller simply needs to be plugged into the 7-Way on the tow vehicle and it will work as it should. When converting your 4-Way to a 7-Way with an adapter like the Curt # C57102 you will only need to run the 12V power wire up to the vehicle's battery like you mentioned. The brake output pin on the 7-Way does not need to be...
    view full answer...
  • Recommended 7-Way Connector for a 2013 Honda CR-V
    To add a 7-way connector to your 2013 Honda CR-V you will first need a 4-flat connector like item # 118561. This will control your trailer's lights if you do not already have one. The second harness you will need is the Universal Installation Kit for Trailer Brake Controller item # ETBC7. The kit includes a pre-wired 7- and 4-way trailer connector that mounts easily at the rear of your Honda with an included bracket. This kit is designed for use on a vehicle with an existing 4-way flat...
    view full answer...
  • Factory Trailer Wiring Harness Connection Point on a 2001 Toyota Highlander
    If your 2001 Toyota Highlander came with a factory tow package then there is a connection underneath. But if it did not come with a tow package the connector will either A) not be there or B) not be functional. On vehicles that have the connector it is located behind the rear bumper. On some, it is located behind the bumper and inside of a plastic box. Take a look at the instructions I have linked for harness # 118245 which should help you locate the harness if it is present on the vehicle. If...
    view full answer...
  • Adding a 4- or 7-Way Trailer Connector to a 2017 Chrysler Pacifica
    The trailer wiring harnesses for the 2017 Chrysler Pacifica do not require identifying the tail light wires and splicing in a harness. There are a couple of options depending on the trim level of your Pacifica. If you have a Limited model use # 118712. And if you have an LX or Touring model use # 118723. Both of the above harnesses are 4-Ways. To add a 7-Way you would first need to install one of them. Then to add a functional 7-Way, retain the 4-Way, and to have the wiring for a brake...
    view full answer...

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