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  1. Custom Fit Vehicle Wiring
  2. CURT
  3. Universal Fit
  4. Trailer Hitch Wiring
  5. 4 Flat
  6. Powered Converter
Curt Tail Light Converter with 4-Way Flat Trailer Connector

Curt Tail Light Converter with 4-Way Flat Trailer Connector

Item # C56175
Our Price: $26.42
You Save: 54%
Custom Fit Vehicle Wiring

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Built to last, this tail light converter with a 76" 4-way flat harness is made using surface-mount technology. Designed for vehicles that have amber turn signals and incandescent bulbs. Includes wire taps and color-coded wires. 1-800-940-8924 to order CURT custom fit vehicle wiring part number C56175 or order online at Free expert support on all CURT products. Great prices and Fastest Shipping for Curt Tail Light Converter with 4-Way Flat Trailer Connector. Custom Fit Vehicle Wiring reviews from real customers.
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CURT Custom Fit Vehicle Wiring - C56175

  • Universal Fit
  • Trailer Hitch Wiring
  • 4 Flat
  • Powered Converter
  • CURT

Built to last, this tail light converter with a 76" 4-way flat harness is made using surface-mount technology. Designed for vehicles that have amber turn signals and incandescent bulbs. Includes wire taps and color-coded wires.


  • Provides a 4-way flat trailer connector at the back of your vehicle to power your trailer's signal lights
    • Compatible with 5-pole, 6-pole, and 7-pole adapters (sold separately)
  • Ensures that your vehicle's wiring matches that of your trailer
  • Designed with safety in mind
    • Guards against electrical shorts and mis-wire situations
  • Connects directly to your vehicle's wiring with the included quick-splice connectors
    • Bonded wires are color coded to ease installation
  • Resists shock and vibration for superior operation on rough roads
    • Circuit board is constructed using surface-mount technology (SMT), an improvement over through-hole construction
  • Includes a durable, molded-rubber, female output socket with protective dust cover


  • Application: vehicles with 3-wire electrical systems and incandescent tail lights
  • 4-Way harness length: 76"
  • Ground wire length: 16"
  • Splice-in wire length:
    • Brown, red, yellow: 16"
    • Green: 60"
  • Max amperage:
    • Turn lights and brake lights: 3 amps per circuit
    • Tail lights: 5 amps per circuit
  • 1-Year limited warranty

Do I Need a Tail Light Converter?

Difference between 2 wire systems and 3 wire systems

Some vehicles operate on a 3-wire system, wherein the brake signal and the turn signals run on separate wires to illuminate different lights. (Typically, these vehicles have amber turn signals.) But most trailers run on a 2-wire system, which means the brake and turn signals travel along a single wire. You'll notice that, on your trailer, the brake light will flash for the turn signals.

If your vehicle operates on a 3-wire system, it will need to be converted so it will be compatible with the wiring system of your trailer. This is where a tail light converter comes into play. This converter lets you combine the brake and turn signal functions of your vehicle so they run on a single wire to properly activate your trailer's tail lights.

Converter Wiring Configuration

Wire Color Wire Function
Green Right turn
Brown Tail lights and parking lights
Red Brakes
White Ground
Yellow Left turn

Tail Light Converter Installation

To begin the installation, use a circuit tester (sold separately) to double-check the function of each wire on your vehicle's tail light wiring harness. The color/function of the splice-in wires on this converter may not match the color/function of those on your vehicle, so you'll want to be sure to check all of the wire functions first. Once you've figured out the functions of your vehicle's wiring, use the included quick-splice connectors to connect the corresponding wires on the trailer connector. Quick-splices, or "wire taps," offer a quick way to make connections without you having to strip and twist wires. Just place the wires in one of the taps and snap the cover down.

Use double-sided tape to stick the converter box to a flat surface inside your vehicle near the tail lights. It's helpful to clean the surface first so the tape can adhere fully.

How to find a grounding point

Find a raw, unpainted metal surface to use as a grounding point and secure the white ground wire with the included self-tapping screw. Cleaning the surface prior to securing the white wire will ensure the converter is fully grounded. Finally, secure the converter wires to your vehicle using cable ties (sold separately).

Quick Tips:

  • Butt connectors - especially heat-shrink ones - provide the most secure, longest-lasting connection, so we'd recommend you grab a few and swap them out for the quick-splices in this kit.
  • Use a circuit tester on the plug terminals once the harness is installed to make sure everything's working. There's nothing worse than figuring out that you have a bad ground or a faulty connection right before you're about to hit the road.
  • Be sure to put a little bit of dielectric grease on the 4-way plug to protect the terminals from dirt, grime, and corrosion.

Built Using Surface-Mount Technology

Curt SMT Circuit Boards

Curt builds each tail light converter using surface-mount technology (SMT). This construction method involves soldering electronic components directly to the surface of a printed circuit board. SMT eliminates the need for leads, which are used in older through-hole technology. The result is a smaller circuit board that provides more routing area and that offers superior performance, reliability, and durability.

Circuit boards constructed using SMT perform better under rough conditions with excessive vibration than those made using the through-hole method. And where would vibration be more likely to occur than in towing applications? Curt converters also produce less heat, increasing durability and lifespan. In addition, lower resistance levels ensure better performance, especially for parts that operate at higher frequencies.

Each Curt circuit board is made using high-quality components pieced together in the most technologically savvy fashion, leading to greater predictability and reliability in functioning.

56175 Curt Wiring Harness with Vehicle End 4-Pole Connector and Tail Light Converter - 76" Long

Installation Details C56175 Installation instructions

This Product Fits The Following Vehicles

California residents: click here

Customer Satisfaction Score:

Customer Reviews

Curt Tail Light Converter with 4-Way Flat Trailer Connector - C56175

Average Customer Rating:  4.6 out of 5 stars   (343 Customer Reviews)

Built to last, this tail light converter with a 76" 4-way flat harness is made using surface-mount technology. Designed for vehicles that have amber turn signals and incandescent bulbs. Includes wire taps and color-coded wires.

2004 Honda Civic

Worked great on my honda civic.



I bought and installed the wiring harness a year ago and its been working great! Thank you etrailer for a great product

Etrailer Expert

Mike L.


@Matthew You're very welcome!


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.

Brooke M.


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.


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!


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.

1996 Ford Escort

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


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

Etrailer Expert

David B.


Ill have CS reach out to you William. In the meantime I would double check your grounds, look for damaged wires and loosecorroded connections.

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.


Great job.


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.

Etrailer Expert

Jenny N.


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.

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.


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?

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.


Great product the wire taps are a little tricky they should include extra taps since they break easily. Overall good product.

2004 Saturn Vue

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


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

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!

Etrailer Expert

Patrick B.


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.

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

David W.


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


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

Etrailer Expert

Brooke M.


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.

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 .


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.

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.

Etrailer Expert

Patrick B.


The video we have for wiring is for Tow Ready part 118372. We have installed it on both a 2002 and 2004 XL-7.

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