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

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

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Custom Fit Vehicle Wiring
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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. 1-800-940-8924 to order CURT custom fit vehicle wiring part number C35FR or order online at etrailer.com. Free expert support on all CURT products. Great prices and Fastest Shipping for 7-Way to 4-Way/5-Way Trailer Adapter for Vehicles with Lamp-Out Sensors Towing Trailers with LEDs. Custom Fit Vehicle Wiring reviews from real customers.
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  • Reviews (119)
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  • Videos (2)
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CURT Custom Fit Vehicle Wiring

Highlights

  • Multi-function compatibility: Connects 7-way to 4-way/5-way trailer LEDs effortlessly.
  • No lamp-out errors: Designed for vehicles with lamp-out sensors like Audi and Mercedes.
  • Simple plug-and-play: Easily connects without complex wiring; ideal for quick setup.
  • Durable construction: High-quality build withstands regular use and road conditions.
  • Ideal for LED trailers: Prevents dashboard warnings with LED-equipped trailers.
  • Perfect German car fit: Solves LED taillight issues in BMW, VW, and Porsche models.

Features to know about

Say Goodbye to Dashboard Alerts: Adapter for Vehicles with Lamp-Out Sensors

If you've ever been frustrated by those annoying dashboard warnings when connecting your LED-equipped trailer, this adapter is your go-to solution. Designed for vehicles with complex lamp-out sensors, such as those found in German cars like Audi, BMW, and Mercedes-Benz, this adapter ensures seamless compatibility. It plugs into your vehicle’s 7-way connector and adapts it to a 4-way or 5-way flat trailer connector, making sure those pesky error messages are a thing of the past.

Plug and Go with No Fuss: 7-Way to 4-Way/5-Way Compatibility

Simplify your towing experience with the versatile 7-Way to 4-Way/5-Way Trailer Adapter. Whether you drive a Porsche Cayenne or a BMW X5, this adapter connects effortlessly to your trailer's LED lights. It’s specially built for vehicles with a factory tow package, solving the low power draw issues that typically trigger bulb-out sensors. Just plug it in and you're good to go — no complex wiring required.

LED Light Issues Solved: Built-In Resistors

Have you ever dealt with hyperflashing or errors when using LED lights on your trailer? This adapter comes with built-in resistors, eliminating these problems by simulating a higher load to satisfy your vehicle's electrical system. Designed especially for trailers equipped with LED lights, it ensures that all your tail, brake, and turn signals function without a hitch.

Perfect Match for Advanced Vehicles: Works on Modern Audi and VW Models

Driving a sophisticated 2024 Audi Q8 or VW Atlas? This adapter is engineered to meet the advanced electrical needs of such vehicles. It allows their smart systems to recognize LED lights on your trailer, enabling safe and efficient towing. With this adapter, compatibility with your advanced vehicle’s lighting technology comes easy.

Easy Transition Across Lighting Systems: Compatible with Older Models

For those who switch between newer LED-equipped trailers and older trailers with incandescent bulbs, this adapter makes life easy. It’s perfect for older vehicles, like a 2004 Sprinter, that struggle to recognize newer LED lights. Just plug it in, and enjoy full functionality of your trailer's lights, regardless of the system.

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

Item # C35FR




California residents: click here


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 Satisfaction Score:

Ratings & Reviews

4.7

118 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.

by:

Functions perfectly. Mercedes Sprinter and other German makes have circuits that fail to recognize LED lighting that is common today. The C35FR adapter solves the issue and is plug and play. Buy with confidence from e-trailer. Great customer from the PROS.

Gwendolyn Y. profile picture
Etrailer Expert

Gwendolyn Y.

4/28/2025

Thanks for saying that, Lynn! You're just as much of a pro as we are :)



by:

installed low profile LED lights on a '98 vintage Kendon motorcycle trailer. They worked when hooked up to my BMW X5, but would also blink every 2 seconds, and showed "bulb out" faults in the diag display.The Curt resistor 7 to 5 plug solved the problem.

Gwendolyn Y. profile picture
Etrailer Expert

Gwendolyn Y.

6/28/2025

That's awesome to hear, James! What kind of motorcycle are you hauling on your trailer?

James profile picture

James

6/28/2025

@GwendolynY It's a 2023 Ducati DesertX ADV bike. I've put 28k miles on it in the 2 years of ownership.
Gwendolyn Y. profile picture
Etrailer Expert

Gwendolyn Y.

7/2/2025

@James I'm a little familiar with the Ducati name but not the specifics so I looked up your bike. It's a pretty nice looking bike! Do you have a go-to spot to ride it at?
James profile picture

James

7/2/2025

@GwendolynY Ive ridden in Texas, Oklahoma, Colorado, Kentucky, Carolinas, Georgia, Florida....really getting around.
See All (4) Replies to Gwendolyn Y. ∨


by:

This is an essential item for towing my LED equipped trailer with my 2023 Volvo. Without it my car does not recognize the trailer being connected and does not go into towing mode.

Bill profile picture

Bill

7/13/2025

One year on and its still working, still doing the job I need it to do.



by:

This along with the Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector (part #30717) solved the lamp-out sensor error for our 2013 Ford Escape while towing a trailer. We are so grateful for the excellent videos that etrailer provides with so many of their products.

Brooke M. profile picture
Etrailer Expert

Brooke M.

4/2/2025

I am so happy to hear that took care of it! It's also really great knowing our videos actually help our neighbors from time to time :) Thanks, Cathleen!



by:

I was getting different error messages with the new LED lights I installed on my trailer. Sometimes the truck would say "check trailer connection" and other times it would say "trailer light out." This adapter solved it - no more error messages. Works like a charm.



by:

Your adapter made the LED tailgate light strip flawlessly. Thank you for being able to have a solution to this problem.



by:

Doesn’t work with Tesla Model Y and LED lighting, while the Tesla sees the lighting it doesn’t do anything. I’m using the Hollywood LED bike rack flexible light bar on my Hollywood bike rack. The Hollywood LED works great with my wife’s Prius C, I wired the system myself for electrical connections. Unfortunately it doesn’t work with the Tesla Model Y from 2025 (not the Juniper edition).



by:

Fixed most of the problems on my Sprint but the Blind Spot warning is still disabled.

E-trailer's customer service is second to none. Any company that deals with the public should take a look at how
E-Trailer treats their customers This is how a customer should be treated.



by:

I use this adapter to silence the rear obstruction warning when my older hitch mount Kuat Serpa bike rack is attached to a 2025 Porsche Macan 4S EV trailer hitch. Seems very well made and durable.

Brooke M. profile picture
Etrailer Expert

Brooke M.

6/19/2025

That's awesome! What kind of biking are you into?



by:

This adapter attempts to make an analog vehicle trailer system see LED lights, but disables the entire blind spot system.



by:

My trailer running/tail lights were not working due to the truck’s system not recognizing the LED lights. This was a simple “plug and play” solution that seems to be working great!



by:

Quick delivery, great customer service, and follow up. The product works as advertised.



by:

etrailer.com you never cease to amaze me at how well you do with customer information, fulfilling orders and help after product arrival. Nice people you are!



by:

It fit tight. I expected slack and blinking lights. It worked great and forgot about it the rest of the trip. Impressed.



by:

I like the info on the employees.Tracking is great.OH by the way the trailer adapter works.If I need more for my trailer I will use etrailer
Thanks



by:

Used on a 2012 Mercedes-Benz Sprinter, Factory tow package with a Kuat piston pro x bike rack. Totally makes the brake, turn signals, running lights work on the rack.



by:

Exactly what I needed I have a new 2024 VW atlas and needed the adapter to use for my trailer which had the 4 pin works great fast service



by:

Works as should. Plug and go.



by:

Excellent service as always!



by:

EXACTLY what I needed. My problem was we need the lamp on the lifted license plate on our mobility ramp and that constantly causes the lamp outs on Kia 2024 Telluride to alarm. After applying the plug, no more warnings! Thank goodness! What an obnoxious feature!



by:

C35FR solved the issue with my 2016 F150 not recognizing Hollywood Racks Light Bar.((Etrailer part HLY54RR). The light works as designed with this adapter.



by:

This adapter is perfect for enabling LED trailer lights for use with an older vehicle that uses incandescent lights. In my case, I use a 2004 Sprinter as a tow vehicle, and without this adapter, I had no brake lights, turn signals, or flashers on a Wells Cargo trailer built in 2014. With the adapter, all trailer lights work! Other solutions exist to fix this problem, including external resisters that provide sufficient load to trigger the lights, but this adapter is the perfect simple fix.



by:

Problem solved. 2024 GMC Sierra pickup. Truck would not recognize trailer because of LED lights on trailer. Everything works as new and suppose to . THANKS



by:

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



by:

I'm so impressed with the products & services I've received from etrailer.com!


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Show More Reviews

See what our Experts say about this CURT Custom Fit Vehicle Wiring

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  • Trailer Wiring Connection Needed for 2006 Lexus GX 470 with Connection Under Bumper
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    Yes, it will. You have to trick the 7-way on your Volvo Xc90 into thinking you're towing something. You'll want to use the following parts: 7-Way to 4-Way/5-Way Trailer Adapter for Vehicles with Lamp-Out Sensors Towing Trailers with LEDs item # C35FR Curt Auxiliary LED Indicator Lights item # C53201 What year is your Volvo?
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    German engineered vehicles such as your Mercedes ML350 do have problems with LED trailer lights. A powered converter could solve the issue but there are also special adapters that create more draw that will allow the affected vehicles to tow a trailer with LED lights and not have that bulb out sensor issue. I would need to know the year of your Mercedes ML350 to make a wiring harness recommendation. You would need to have a 7-Way wiring harness on the vehicle already to use the adapters....
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