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Curt Circuit Protected Converter w/ SMT

Curt Circuit Protected Converter w/ SMT

Item # C56175
Our Price: $27.29
Trailer Wiring

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To see if this custom-fit item will work for you please tell us what vehicle you'll use it with.

Shipping Weight: 0.69 lbs
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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. Great Prices for the best trailer wiring from CURT. Curt Circuit Protected Converter w/ SMT part number C56175 can be ordered online at or call 1-800-940-8924 for expert service.
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  • Reviews (341)
  • Q & A (0)
  • Photos

CURT Trailer Wiring - C56175

  • 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

Installation Details C56175 Installation instructions

This Product Fits The Following Vehicles

California residents: click here

Customer Satisfaction Score:

Customer Reviews

Curt Circuit Protected Converter w/ SMT - C56175

Average Customer Rating:  4.6 out of 5 stars   (341 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.


ups sent me a email stating eta aug 7
part nlt friday paid extra for o/n service
called etrailerw/eric and he traced the and said it would be here as irequested
thanks for correcting ups msg

will use your company for any parts i may need and also as we travel will recommend your company
thanks tom walters

1996 Geo Tracker


2000 Honda Civic

The online fit guide stated that this would work for my 2000 Honda Civic, but after installation (double checked for proper installation) only one brake light worked on the trailer.

I am sorry to hear you are having issues with this. It sounds to me like there is a bad ground connection. You may want to double check once more and just make sure your ground wire has a direct, clean, and secure connection. So often, when it comes to wiring, the ground connection is the issue.
Brooke M - 01/23/2023


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!

1996 Ford Escort

Nice quality because the shank that goes into the hitch is solid but hallow like the ones from other sources.

2009 Kia Sportage

This kit worked perfectly for my 2009 Kia Sportage. It had all of the parts I needed and the only real challenge was trying to identify the correct wires to splice into.

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


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.


Did not work with my application. To this day I still don't have working trailer lights.

Ill have CS reach out to you William. In the meantime I would double check your grounds, look for damaged wires and loosecorroded connections.
-- Etrailer Expert David B - 10/08/2022


I never installed it. I expected plug in vehicle-specific harness part number 55522 for my 2003 Toyota Echo I had ordered and received from you before for my 2000 model and you sent me this useless piece of electrical shinola. May I still return it as it is unopened?


Clear and concise instructions made install a breeze. Great product.

2012 Toyota Yaris

a good easy to install product


Easy to hook up


Transaction went great , arrived when specified . Have not installed yet, that will happen next week .

2007 Toyota Yaris

Looks like a simple install. Pretty quick shipping to Canada.


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


The instructions were clear as well as the label on the converter box. My only issue was the ground screw and recommended size hole did not result in a snug connection to ground (which would compromise the entire system). I found a larger sheet metal screw and resolved the problem (on a whole, this was not a big deal); just make sure you ground screw is snug.


I always get the best customer service from etrailer and that’s why I keep coming back to buy anything I need for towing. Oh, and their prices are great too.

2004 Saturn Vue

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

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

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

1993 Honda Accord

Well designed

2009 Toyota Yaris

I got this for my 2009 Yaris. Works great to pull my Kayak trailer. Installation was pretty easy also.


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.

1996 Ford Aerostar

This kit worked great. Your car or truck may need a little extra wire for the right turn signal but I am very very happy with the quality of the materials and install. Hauled my trailer safely today and did not have to redo any connections!

It works
mj - 02/06/2016

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