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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: $40.19
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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 (58)
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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   (58 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.


Perfect fit with easy installation inst ructions!


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


Works great!


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.

Etrailer Expert

Sierra K.


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.


Installed perfect .. love it





good product.


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


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


Great product....easy wiring and flawlessly


Easy installation


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.


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.


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


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.




great product at a good price shipped f ast

Show More Reviews

See what our Experts say about this CURT Trailer Wiring

  • 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...
  • 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...
  • 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...
  • 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...
  • 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 Curt 7-Way Require a 12 Volt Charge Line To Be Connected When Brake Controller Isn't Needed
    When installing the Curt Trailer Connector Adapter with Backup Alarm # C57102 you will only need to connect the dedicated 12 volt power wire if your trailer requires a power wire. There are several trailers like small pop ups which tie into the 12 volt charge line to maintain power for a refrigerator or heating system and the trailer will not require the operation of brakes. With that said if the trailer has electric brakes you will need to have a controller like the Curt Echo # C51180...
    view full answer...
  • 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...
  • 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...
  • 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...
  • 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...
  • 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...
  • Reccommended 7-Way Wiring Harness for a 2023 Ford Bronco Big Bend
    If you've already got a 4 pole, you can just use the Universal Installation Kit for Trailer Brake Controller # ETBC7 to add a 7 way to your Bronco. It won't really matter what kind of bulbs your Bronco uses, you'd just need to have a 4 pole already to tee into this harness which you have so you'll be all set.
    view full answer...
  • Can You Run a Battery Charge Line with Magnetic Dinghy Tow Lights
    I do have an option for you but there isn't a great way to run a battery charge line between the towed vehicle and motorhome when using a set of magnetic tow lights. I instead switching to didoes which use a 7 to 6-way umbilical so you can run the battery charge line through the trailer connector. The Roadmaster Diode 7-Wire to 6-Wire Flexo-Coil Wiring Kit part # RM-15267 is what I recommend. The good news is that you can take the umbilical with you to the new vehicle but we don't have...
    view full answer...
  • Solution for 2020 GM Truck that Won't Recognize Trailer Wiring Connection
    What you need is more resistance on your trailer wiring circuits so that your truck thinks a trailer is connected. So what you could do is install the load resistors part # DI34ZR on two of your trailer wiring circuits and your truck would draw more amperage when connected and you'd be good.
    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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  • 7 & 4-Way Adapter With The Shortest Rear Clearance Requirement
    The shortest 7 & 4-way option we currently offer is the Hopkins Endurance Multi-Tow 4-Way Flat to 7-Way RV Trailer Adapter w/ 4-Way Vehicle End Plug # HM47180 The Curt options, like the # C57102 you were looking at, all require 3-4" of clearance behind the port for the cable. The Hopkins Endurance # HM47180 only requires approximately 2-1/2" of clearance. If this still isn't enough then you can use a long bracket # C57202 to push the socket out further for more clearance.
    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...
  • 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...
  • What is Needed to Add 5-Way to Vehicle For Boat Trailer With Disc Brakes
    So you won't actually need a 7-way as your boat trailer has hydraulic disc brakes and a 7-way is for electric brakes. All you need is an adapter for the 4-way on your Highlander to make it a 5-way: - Curt Trailer Connector Adapter - 4-Way Flat to 5-Way Flat - Vehicle End # C57187 This is not a difficult DIY, you'll just need to tap into the reverse light wire of your Highlander, and I have added a link below to a video which shows an example of this. It's on a different vehicle but it...
    view full answer...
  • Recommended 4-Way and 7-Way Connectors for a 2023 Chevy Traverse
    I have both a 4-way and 7-way connector that are custom fit for your 2023 Chevy Traverse. They are the 4-Way Curt T-Connector Vehicle Wiring Harness item # C56394 and the 7-Way Curt T-Connector Vehicle Wiring Harness item # C56393. These custom-fit T-connectors plug into your Traverse's wiring harness, which is located above the muffler on the driver's side. I have linked a couple of installation videos for both below. Neither one of them have a back up alarm. The only option to purchase...
    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...
  • 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...
  • Correct Adapter Harness for Curt Echo Brake Controller on 2018 Toyota Highlander
    In order to install the Curt Echo Wireless Brake Controller part # C51180 on a 2018 Toyota Highlander with four way flat you need the 7-Way RV Upgrade Kit for Trailer Brake Controller Installation part # ETBC7L which is an adapter designed specifically for this brake controller. It has everything you need for the installation. The two four way ends will plug into each other that will then leave you with a few wires. The blue and yellow are not used and can just be taped up. The black wire...
    view full answer...

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