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Curt Circuit Protected Converter w/ SMT

Curt Circuit Protected Converter w/ SMT

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Trailer Wiring

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Install a 4-way trailer connector on your vehicle with this wiring harness with tail light converter. Harness splices into existing wiring. SMT construction ensures superior performance. Lowest Prices for the best trailer wiring from CURT. Curt Circuit Protected Converter w/ SMT part number C56175 can be ordered online at or call 800-298-1624 for expert service.
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  • Reviews (295)
  • Q & A (0)
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  • Why etrailer?

CURT Trailer Wiring

  • Trailer Connectors
  • Vehicle End Connector
  • 4 Flat
  • Plug and Lead
  • CURT

Install a 4-way trailer connector on your vehicle with this wiring harness with tail light converter. Harness splices into existing wiring. SMT construction ensures superior performance.


  • Provides a 4-pole flat trailer connector for the vehicle
    • Compatible with 5-pole, 6-pole and 7-pole adapters (sold separately)
  • Hardwires to existing harness behind tail lights
  • Solid one piece construction
  • 16 Gauge bonded wire with 4-flat plug
  • Factory appearance
  • Simple do-it-yourself instructions on every package
  • Not recommended for vehicles with LED lights


  • Wire configuration:
    • Red: brake lights
    • Yellow: left turn lights
    • Green: right turn lights
    • Brown: Tail lights
    • White: ground
  • Wire gauge: 18
  • 1-Year limited warranty

Tech Tip: It is always a good idea to apply a small amount of grease to all electrical connections to help prevent corrosion.

Warning: Overloading circuit can cause fires. Do not exceed lower of towing manufacturer rating or:

  • Max. stop/turn light: (3 amps)
  • Max. tail lights: (7.5 amps)

Read vehicle owner's manual and instruction sheet for additional information.

Surface Mount Technology (SMT) is a method for constructing electrical circuits where components are mounted onto the surface of printed circuit boards.

56175 CURT Vehicle Wiring Harness - 4 Wire

Item # C56175

Installation Details C56175 Installation instructions

This Product Fits The Following Vehicles

California residents: click here

Customer Reviews

Curt Circuit Protected Converter w/ SMT - C56175

Average Customer Rating:  4.7 out of 5 stars   (295 Customer Reviews)

Install a 4-way trailer connector on your vehicle with this wiring harness with tail light converter. Harness splices into existing wiring. SMT construction ensures superior performance.

- C56175
2004 Volkswagen Jetta

I've been using this wiring harness for around a year now and it's performed amazingly. I have a 2004 VW Jetta Wagon, picked up some cheap female "pin" connectors as my taillights on my car had pins that you could just slide a connector on to. I was able to use this method to install this harness without actually cutting into any of my cars wiring. Working amazingly.

Still working great 2 years after purchase. No complaints at all.
Corey - 05/06/2022

- C56175

eTrailer gets a grade of A+. The actual part gets a grade of B-. Two of the wires arrived slightly damaged - luckily near the cut end so I didn't have to lose much length. The sticker identifying the 4 wires on one side and 5 wires on the other was upside down, so I peeled it off and reapplied (my OCD kicking in!). I wanted to keep my original quick release plugs on 1996 Jeep Cherokee Sport & was able to do that. Used heat shrink connectors between them & Curt Converter. All lights on vehicle & trailer working perfectly again!

- C56175

Easy enough to install, I would have liked a little bit more wire on the vehicle side of wiring. Not a huge fan of splice clips, but not enough to provide my own, would like better proper crush and heatshink splicing. Just installed, so no comment of longevity or reliability.

- C56175

I bought this kit for my 1994 Jeep Cherokee XJ and while it seemed like a good purchase at the time, unfortunately after installing it myself found issues with it. Driving lights on the trailer worked as they should, left and right blinker were extremely dim as were the brake lights. I tried a friends trailer and had exactly the same issue. Used a multimeter to check for correct voltage and continuity, everything seemed to check out fine. Problem persisted even after taking it to an auto electrician, so after about a month of trouble shooting and spending more money than I wanted to in diagnosis I ended up buying another 'plug and play' from a local auto parts store and after installing that one myself all the problems I had before vanished.

I will have our Customer Service team reach out to you. It is possible that the ground also needed to be checked. We do have a FAQ that helps with trouble shooting.
-- Etrailer Expert Jenny N - 04/07/2022

- C56175

It was not as easy as the plug and play units I’ve installed on other cars. It occasionally causes turn signal function issues but seems to work most of the time.

- C56175

Nice kit, worked great for a month. Now it doesn't turn the brake lights or tail lights.

A common cause for this type of issue is a bad ground connection or bad wiring connection. You will want to make sure all connections are secure and make sure your ground is at a direct, clean, and secure point.
-- Etrailer Expert Brooke M - 04/27/2022

- C56175

Fit my car and easy to install and good instructions included well made would buy again.

- C56175

Its average. Insulation on wires is poor. Wires not copper.

- C56175

The quick splice were a bit oversized for my Audi wiring. Required me to wiggle it a bit to get a good connection to the, my guess 22ga, wire. Could also use at least a few more zipties. Otherwise, this is a good kit.

- C56175
1996 Jeep Cherokee

Something is defective with this unit. While the running light circuit is fine, the circuits that convert the brake and turn signals into a single circuit (the essence of the device) is intermittent; sometimes it works properly, sometime only the left light responds, sometime only the right, sometimes nothing. I believe the problem is due to a bad diode in the unit. I am experienced with these devices, so it is not an installation error. Due to the installation, I am unable to return the unit in unused condition. 1996 Jeep Cherokee. FYI- this unit was purchased to replace a similar unit that started having a different problem after ten years of use.

When a wiring harness is acting up, the first thing youll want to do is isolate the cause to the vehicle or the trailer wiring. Use a standard incandescent circuit tester like our part 40376 on each pin of the trailer connector as each function is activated. If youre not getting signal on the trailer connector pins, try testing on the input side of the converter. If the signal is entering but exiting the converter box, youll have confirmed that the converter is bad. Youll also want to ensure that the ground connection is secure. An insufficient ground can cause all kinds of odd behavior in the lighting. Ill link you to an help article on trailer wiring troubleshooting.
-- Etrailer Expert Mike L - 10/10/2018

- C56175

Pretty straight forward install and made easy with quick connects

- C56175
2005 Hyundai Elantra

OK this product is great, installs quickly with the supplied tap connectors and works as expected. i installed on a 05 Hyundai Elantra. Do yourself a favor and save yourself hours of troubleshooting. take some sandpaper and scratch off the paint on the metal surface of the car. I did it inside the light access panel. Use the supplied self tapping screw to make a Solid ground or your trailer lights will not work! i took a shortcut and secured to a screw in the panel, with paint under it. While this was sufficient ground for my test light, it was not for the trailer lights. <- this really threw me off and i wasted a lot of time troubleshooting. i even thought my trailer lights were bad and got a replacement set! but no good until i grounded properly. PS tech support was AWESOME! i had to call twice, once for the hitch install, another for trailer light issue. they answered my questions quickly and even helped me troubleshooting my trailer light issue!. When it comes time to get a hitch for my wife's van, i am definitely re-ordering from

- C56175
2003 Saturn LW300

The trailer wiring adapter worked fine on my 2003 Saturn LW300. The unit construction was excellent. I did have to spend a while finding the proper wires in areas that were practical to splice in and had to do a lot of "pinning" with a voltmeter to determine which wire carries the correct signal. This may be difficult for someone with little experience in wiring. Most connections were made in the spare tire compartment with one behind the right tail light, all within the vehicle. Overall I am very satisfied with the product.

- C56175
2009 Hyundai Accent

Easy to install

- C56175
2019 Dodge Durango

The product is WELL worth the small price paid & more! Ease of installation was great! My 19 month old daughter had to help Dad & it took us about 30 minutes. My daughter had to view every step along the way!! Basic tools, Phillips screwdriver, pliers, light/line tester & drill with bits were all that was needed. I installed it to replace the factory installed trailer harness on a 1998 Dodge Durango. SUPER easy to get to the tail light wires ( only 2 screws per light). I unplugged the light housing to make it easier to clamp into the correct wire and to find the correct wire to clamp onto. **NOTE: The wire color on the vehicle harness does not match the color code on the C56175. Thus the reason for the light/line tester!! ALSO where I mounted the converter box was in the plastic louvers inside & behind the light housings. It fit snug but was in a safe & dry place. I could not take pictures but I assure you the EASE of installation was quick, simple & great the 1st time! Absolutely no problems even for the novice! Thank-You etrailer for such a great product at such a great price!! I would highly recommend this product..

- C56175

Easy to connect and works great

- C56175
2010 Jeep Liberty

These items are just as they are said to be. Installation was fast and easy. I would highly recommend Trailer and these products. I will buy from them as the need arises.

Still very happy with this product. Hasnt given me any problems. Going to be purchasing another for my other jeep.
Ken - 12/06/2014

- C56175
1999 Toyota Tacoma

Good price, product was perfect, and the shipping was quick. Problem solved. T-taps are sort of miserable, but that's on the installer, not the product - cutting, soldering, and heat shrinking is definitely the way to go. If you have a problem with your 'Yota truck lighting acting wonky, chances are very high this unit is your issue! Mount it up high, on the bottom of the bed to keep it dry and give it decent life. The harness cover is a nice touch that does not come with all of these - pack it with dielectric grease, and you'll get many years out of this. Good job, etrailer!

We have seen some wonky trailer light issues with Toyotas when adding aftermarket harnesses like this. Typically the issue is the ground. The Toyota frames do not ground as easily as other makes. Sometimes we have to move the ground or extend it to a factory ground point in order for the system to function correctly.
-- Etrailer Expert Patrick B - 03/04/2013

- C56175
1998 Volkswagen Beetle

The Circuit Protected Converter # SMT C56175 trailer lighting harness for my 1998 VW Beetle arrived within a few days and was easy to install with the include instructions! All trailer lights worked perfect the first time they were checked after the install! Great job to ALL of you at

From the day I installed the SMT C56175 Converter, I have had no problems at all! This is a well designed, high quality item that I would highly recommend to anyone!This item still gets a five star rating all day long!All The Best,David W
David W - 01/04/2015

- C56175
1992 Geo Tracker

Excellent customer service! I'lllet you know more once the item is installed.

- C56175
1999 Oldsmobile Intrigue

Fairly easy to attach just had to double check the wiring on the car and had to sandpaper away some paint in order to get a good ground connection.

- C56175
2004 Saturn Vue

Was very happy and satisfied with my purchase and delivery of my product. Insulation went very well.

- C56175

great wire harness, could not have been easier for the "common man" to deal with ! came with the hitch, I paid for it, but same package so didn't have to wait for a second box.

Darrell N - 06/17/2015

- C56175
Suzuki XL7

The product works fine. I Youtube video for installing a harness on a Suzuki XL-7 IS NOT this product. If you're not a very handy person you may have problems getting this installed. I figured it out but I'm pretty handy. The video show them just plugging it into a 6 pin connector inside the left rear qarter panel. But the harness itself has no matching connector. You have it splice each wire to a wire on the car.

The video we have for wiring is for Tow Ready part 118372. We have installed it on both a 2002 and 2004 XL-7.
-- Etrailer Expert Patrick B - 11/11/2013

- C56175

I installed this on my motorcycle, a 2004 Honda VTX 1300S. The converter itself is attached beside the license plate, exposed to the weather. It has functioned flawlessly for almost a year now, through Kansas cloudburst, desert heat and mountain freeze. If I should ever need another (not likely), I will get the same model.

A year later and it still works just fine.
Alan - 11/27/2019

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