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7-Way to 4-Way/5-Way Trailer Adapter for Vehicles with Lamp-Out Sensors Towing Trailers with LEDs

7-Way to 4-Way/5-Way Trailer Adapter for Vehicles with Lamp-Out Sensors Towing Trailers with LEDs

Item # C35FR
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Curt 7-way connector to 4-way or 5-way flat connector is designed for use on vehicles with Trailer Lamp-Out sensors when towing a trailer equipped with LED lights. Lowest Prices for the best trailer wiring from CURT. 7-Way to 4-Way/5-Way Trailer Adapter for Vehicles with Lamp-Out Sensors Towing Trailers with LEDs part number C35FR can be ordered online at or call 1-800-940-8924 for expert service.
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  • Reviews (29)
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CURT Trailer Wiring - C35FR

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

Curt 7-way connector to 4-way or 5-way flat connector is designed for use on vehicles with Trailer Lamp-Out sensors when towing a trailer equipped with LED lights.


  • 7-Way RV style adapter to 4-pole and 5-pole flat trailer connectors
  • Designed for use on vehicles with Trailer Lamp-Out sensors - such as Audi, Mercedes-Benz, Porshe, and Volkswagen vehicles with the factory tow package
  • Plugs into a 7-way connector on the vehicle and 4-way or 5-way flat connector on the trailer
  • 1-Year limited warranty

57004 Curt 7-Way to 4-Way and 5-Flat Trailer Adapter for VW, Audi, Porshe, and Mercedes-Benz Towing Trailers with LED Lights

Video of 7-Way to 4-Way/5-Way Trailer Adapter for Vehicles with Lamp-Out Sensors Towing Trailers with LEDs

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

Video Transcript for Curt 7-Way to 4-Way/5-Way Trailer Adapter Review

Hello neighbors. It's Brad here at etrailer. And today we're taking a look at the cut seven to four and five pole adapter. So as the name implies you are able to adapt a factory seven way to a four and five pole. And that's really nice because a lot of vehicles will have the factory seven way on there but maybe not the four pole. So if you look came to hook up to a trailer and realize that they have a four or five pole, you might be out of luck or have to run additional wire to permanently mount it.

Well, that's where this comes into play. So that's gonna allow you to be able to have your seven way, your four pole, as well as your five pole just with plugging into the factory seven lane. Now, sometimes your towing vehicle will not recognize the LED lamps on your trailer. And that's where this is great too as plugging that in is gonna allow this to send that signal to your vehicle making sure that your lights are actually working with your signals. So like our neighbor here they have a trailer with a four pole but they got a new vehicle that has a seven way.

So instead of having to run all new wiring for it you can simply plug this into the factory seven way. You can take your four pole and plug it in or if you have the same vehicle but you're towing a different trailer. This gives you that same ability. So having this is going to allow you to hook up electrically to those trailers. So now let's go ahead and test it.

So first I'm gonna start with my running lights. Next I'm gonna do my left turn signal, my right turn signal. And then finally my brakes. Now this neighbor also toes, a boat trailer. So having the five pole is gonna be really nice for the surge lockout as well as reverse light.

Now, for some of your foreign vehicles or high end vehicles that have LED taillights sometimes they don't have enough power to power the trailer lights. Well, this is gonna help with that. Allowing that to give it enough juice to be able to still retain your lights on the trailer. Something that's really nice about this is the size and that if you normally tow a seven pole you can simply swap this in whenever you're picking up a different trailer and need to hook up or really you can use this to hook up to any trailer. You have that ability and you can keep this in your glove compartment until you need it. And that was a look at the cur seven, two, four and five way adapter..

Customer Reviews

7-Way to 4-Way/5-Way Trailer Adapter for Vehicles with Lamp-Out Sensors Towing Trailers with LEDs - C35FR

Average Customer Rating:  4.8 out of 5 stars   (29 Customer Reviews)

Curt 7-way connector to 4-way or 5-way flat connector is designed for use on vehicles with Trailer Lamp-Out sensors when towing a trailer equipped with LED lights.


Fixed the issue I had with my Mercedes GL550 not switching to towing mode and enabling all the LED trailer lights!


Product ended up not working very well - the funky. chinese wiring was not a straight forward hook up and i got the lights to eventuLly work, but even with an adapter it sets off the lights out computer in my car and i get no brake lights .


Solved the issue of German auto with LED taillights on a trailer.


Roger in Customer Service was simply excellent. Been trying to get a special adapter for my trailer for months (floating on some ship in the Pacific!). He persisted with two suppliers and one showed up today!! He even asked if I wanted to cancel the other order. Really on top of things and found this to be true with this company.


Worked just the way trailer said it would also delivered in time be fire I leave on a trip


I recently purchased this product and it solved the light monitoring system errors that I was having with my 2012 BMW X5. My trailer was equipped with LED lights and the adapter was the perfect solution.


Very Happy with the product and shipping (fast delivery and packaged great.) Thank You. I look forward to future purchased with you.

Highly Recommend



Product seems to work great for my 2016 MB sprinter 3500. And e-trailer’s customer service is top notch, as usual.


The customer service was excellent! I had a question about a lighting system for my tow vehicle and RV. I was directed to a match and they were correct. Not only does it work, they didn’t recommend the highest priced item hence saving me money.


I like that it is a "One piece unit" without external wires


Problem solved! I had ordered a set of the Blazer wireless LED trailer lights for the towed vehicle behind my motorhome. They didn't work. After trying another set that didn't work then calling the manufacturer I was about to give up. However, thanks to Tommie C at etrailer, he recommended this adapter and it resolved the issue. etrailer is the BEST! Great products, great customer service, great technical support.


Great service and prompt delivery!
7 pin trailer light connector works great and allows me to connect easily to my older wire harness.


Plugged in. Works. Nice!


Works great. Solves the problem of LED lights triggering faults on our BMW X5. The lights work and the car electronics don't signal any faults and switch the rear parking sensors off as designed.


Great products and excellent customer s ervice.


This item arrived quickly and on time. Product as described and fixed my issue with my 2020 truck not picking up LED light on my trailor. I spent 60000 on a new truck and have to buy this to get my trailor to work properly. Chevy should be ashamed of themselves! Glad they have products like this.


Works perfect, no more warning lights on my dashboard.


Both ends fit but haven't connected the trailer to test the lights.


Great! Just in time to pick up my new Jet ski... thank you!







Show More Reviews

Ask the Experts about this CURT Trailer Wiring

  • 7-Way to 4-Way Adapter that Can Fit 2021 Volvo V60
    Yes the 7-Way to 4-Way adapter # C35FR would fit the 7-way of your 2021 Volvo V60 and would be a great and easy way to convert to a 4-way like you are wanting.
    view full answer...
  • Recommended Trailer Adapter For Vehicles With Lamp Out Sensors For 2008 Infiniti FX35
    It sounds like you are looking for a trailer adapter for a vehicle with lamp out sensors for your 2008 Infiniti FX35. If that is the case I recommend the 7-Way to 4-Way/5-Way Trailer Adapter for Vehicles with Lamp-Out Sensors # C35FR if your trailer has a 4-way or 5-way connector, or the Trailer Connector Adapter w/ Lamp-Out Sensor Bypass # 20142 if your trailer has a 7-way connector. These sensors are commonly needed on German vehicles with lamp out sensors, or newer domestic vehicles...
    view full answer...
  • Trailer Lights Won't Work on 2011 Mercedes-Benz GL on Trailer With 4-Way
    I'm not sure why U-haul would say it's fine when it clearly isn't, but the problem with the Mercedes is that there isn't enough power draw, so you'd need to use a lamp-out adapter: - 7-Way to 4-Way/5-Way Trailer Adapter for Vehicles with Lamp-Out Sensors # C35FR This will allow the trailer's brake and turn signals to recognize the signals coming from your Mercedes. If you were already using one of these adapters (I wasn't sure if you were talking about one of those or a 4-way to 7-way...
    view full answer...
  • Troubleshooting 2014 Volkswagen Touareg Not Recognizing Trailer With LED Lights
    Based on what you are describing yes, the 7-Way to 5-Way/4-Way Trailer Adapter for Vehicles with Lamp-Out Sensors Towing Trailers with LEDs # TR20141. The Curt # C35FR will also work. The problem is likely that the LED signals from your trailer are not being read by your vehicle's computer. Adapters like this one use built-in resistors to solve that problem. If you need a 7-way the Curt 7-Way Trailer Adapter for Towing Trailers with LED Lights # C57003 is also available.
    view full answer...
  • Adapter Needed To Tow A Trailer With LED Tail Lights With a 2011 Mercedes-Benz ML550
    To make the LED trailer tail lights work with the factory trailer wiring on your 2011 Mercedes ML550 you will need a Trailer Connector Adapter w/ Lamp-Out Sensor Bypass # 20142. This will plug into your 7-way on your ML550 and allow the trailer to plug into it. The adapter tricks the computer in your Mercedes to believe that the trailer does have normal incandescent bulbs so that you do not get the bulb out error on your dash. If you are hauling a smaller trailer the 7-Way to 4-Way/5-Way...
    view full answer...
  • Troubleshooting 2000 Toyota Tundra AC 4.7 V8 4WD With Electric Braking Issue
    For your issue, I recommend just using the Brake and Tail Light Trailer Hitch Receiver Cover for 2" Trailer Hitches # CR-007A when not towing a trailer. It sounds like you just need an incandescent bulb to draw power, so I recommend using this cover which has the bulb. If you pull a trailer with LED lights in the future, the adapter # C35FR and # 20142 have the resistors integrated so there is not need to adapt wiring. The draw on your brake controller shows there may be corrosion because...
    view full answer...
  • Pulling a Trailer With LED Lights and the Vehicle is Reading Lamps Out
    Though we do recommend having a resistor on each LED light, we do have other options as well. Since you mentioned having a 7 Way connector, you could use a lamp out sensor adapter like the # 20142 if the trailer is wired with a 7 Way plug or a # C35FR if you have a 4 Flat or 5 Flat plug on the trailer. These have all the needed pieces to trick the vehicle's computers into working with LED lights on the trailer. That being said, you could spice resistors into each of the wires attached...
    view full answer...
  • Options to Replace Atwood 82543 Hydraulic Brake Actuator
    The Demco Hydraulic Brake Actuator part # DM72VR is for drum brakes which is what you need to replace an Atwood 82543. The other options you're inquiring about are for disc brakes which won't work. In short, there are tons of different versions of the Demco Hydraulic Brake Actuator each with different features such as drum/disc brake compatibility, weight capacity, ball size, lockout type etc. The correct one for the Atwood 82543 is listed above. In order to reverse without the brakes...
    view full answer...

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Info for this part was:

Employee Lindsey S
Edited by:
Lindsey S
Employee Jeff D
Installed by:
Jeff D
Employee Bradley B
Installed by:
Bradley B
Employee Jameson C
Expert Research:
Jameson C
Employee Jacob T
Video Edited:
Jacob T
Employee Dustin K
Video by:
Dustin K
Employee Wilson B
Updated by:
Wilson B
Employee Noah M
Updated by:
Noah M
Employee Kristina F
Written by:
Kristina F

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