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CURT

Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

Part Number: C56174

18 Reviews | 7 Questions

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$89.99

Retail:$154.95

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Not Confirmed to Fit

2010 Chevrolet HHR

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curt custom fit vehicle wiring trailer hitch end connector

curt custom fit vehicle wiring end connector plug-in c56174

curt custom fit vehicle wiring trailer hitch end connector t-connector harness with 4-pole flat

curt custom fit vehicle wiring trailer hitch plug-in t-connector harness with 4-pole flat connector

curt custom fit vehicle wiring 4 flat plug-in c56174

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SCHEDULE AN INSTALLATION

Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. T-connector plugs directly into existing wiring. Powered converter reduces strain on wiring system and is made using SMT to ensure superior performance. 1-800-940-8924 to order CURT custom fit vehicle wiring part number C56174 or order online at etrailer.com. Free expert support on all CURT products. Great prices and Fastest Shipping for Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector. Custom Fit Vehicle Wiring reviews from real customers.

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Reviews (18)
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CURT Custom Fit Vehicle Wiring - C56174

Highlights

Custom Fit for Your Vehicle: Works with your vehicle's wiring
Tow-Ready Setup: 4-way flat plug powers trailer lights for stop, turn, and running signals.
Plug-and-Play Install: T-connectors plug inline at tail lights—no cutting or splicing.
Reliable Signal Match: Built-in powered converter ensures your vehicle and trailer lights sync.
Clean Wire Routing: Color-coded leads—green (right), yellow (left), brown (running), white (ground).
No Tow Package Needed: Adds trailer wiring to vehicles not factory equipped for towing.

Features to know about

Installs Without Cutting or Splicing: Plug-In Harness

Wiring for towing can be tricky, but this Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector keeps it easy. It’s a plug-in design that connects directly to your vehicle’s tail light housing with no splicing or wire tracing needed. The connector with the yellow wire goes to the driver side tail light housing, and the connector with the green wire goes to the passenger side. Once it’s in place, you’ve got a clean, hidden install that’s ready for towing lights.

Reliable Powered Converter: Protects Vehicle Circuits

This harness comes with a powered converter that isolates and protects your vehicle’s sensitive wiring from the trailer’s electrical system. It ensures consistent power delivery to the trailer lights while preventing feedback or overload on your car’s circuits. That means stable lighting every time you hook up, even if your trailer system uses a different wiring setup.

Covers the Basics for Safe Towing: 4-Flat Connection

The 4-flat connector gives you all the essential lighting functions – running lights, turn signals, and brake lights – so your trailer is visible and road legal. The wire colors make setup simple: Green for right turn/stop light, Yellow for left turn/stop light, Brown for running light, and White for ground. Everything is clearly labeled and ready to go.

Works Without a Factory Tow Package: Ready to Use Out of the Box

No factory tow package? No problem. This harness is built for vehicles that didn’t come prewired for towing. It provides everything needed to get a trailer connected quickly and safely. Once plugged in, your vehicle is fully set up with trailer lighting capability—no extra factory parts required.

Specs

Wiring Specifications

Green wire: Right Turn/Stop Light
Yellow wire: Left Turn/Stop Light
Brown wire: Running Light
White wire: Ground

Installation Details

T-connector with the yellow wire: Connects to the driver-side tail light housing.
T-connector with the green wire: Connects to the passenger-side tail light housing.

Comparison and connection diagram for the Curt T-Connector Vehicle Wiring Harness showing connector ends and plug-in points for Fiat 500 installation.

56174 CURT T-Connector - Surface Mount Technology - 4 Wire

Similar to Hopkins HM11140274

Installation Details C56174 Installation instructions

This Product Fits The Following Vehicles

2012 - 2018 Fiat 500
2012 - 2019 Fiat 500 Abarth
2012 - 2019 Fiat 500 excluding Abarth

Customer Satisfaction Score:

95% were satisfied with this product

5% of customers were not satisfied

Wrong item was ordered
Alternate product found

5% of customers were not satisfied

Wrong item was ordered
Alternate product found

4.8

18 reviews

5 Stars		(15)
4 Stars		(3)
3 Stars		(0)
2 Stars		(0)
1 Star		(0)

by: Steve 09/21/2024

2016 Fiat 500

Missing a gasket. This worked well and included quality wire power supply/ground wire. Butt-connectors were of the cheap variant, though, not water resistant by any means. Instructions aren’t clear, no indication of what side the module goes on vs what side the green wire goes. Fine print at the bottom of the instruction sheet showed a wiring legend. Green wire is right. Got it.

The green-wire side T connector is missing its water resistant gasket. Filled it full of dialectic grease to get me going for now.

Click to Enlarge

by: Gary 06/19/2022 One Year Later

Excellent new "plug & play" version to the outdated wire splice type. Solid and dependable. Exact fit for our Fiat. Using the system currently. 5 Stars.

Click to Enlarge

Gary K. One Year Later

6/20/2023

Perfectly. The pigtail wiring is used at least 4 days a week for our mini-trailer for hauling items too large for our hatchback. Still 5 stars!

by: Randy 08/04/2026

Easy installation

by: Robert 05/31/2023 One Year Later

Hesitated for a few weeks ,,,,looked at obstacles ,, then got down to getting it installed. Took me 3 hours fiddling with details and it was completed . A week later one of the taillight fixtures was not locked in perfectly,,, loosened 2 screws and reset the fixture , retightened 2 screws, done

Robert One Year Later

5/31/2024

A year later ! I’m impressed with the wiring harness,,,, no adjustments needed or failures,,,,did replace a trailer lite lens that broke and added a pair of amber side lights and had no effects on the harness

by: Bill T. 09/13/2017

2013 Honda Element

What makes this hitch system a sure winner is the absolute ease and accuracy of the installation. The video is an outstanding addition to walk you through almost everything. I say almost, because the one missing element is a 'how-to' on installing the positive lead to the battery. I'm still wrestling with whether or not to run it internally or externally. Aside from that, I was able to put the rear of my 2013 Fiat Abarth on solid stands which gave me ample room to do everything. Although the video suggested pulling additional supports off of the exhaust system to make it easier, I found that it wasn't necessary (and besides, since the car wasn't on a lift, as in the video, accessibility was a bit tougher). The entire installation took about an hour because I was pausing periodically to watch the video and make sure I wasn't missing anything. Someone more mechanically skilled could probably do this in less than 30 minutes. Well done, etrailer!

by: Michael S. 05/18/2017

Easy installation with the exception of routing the hot lead to the battery. A recommended path would be an improvement here as the coil springs must be avoided.

Michael S. One Year Later

5/19/2018

No problems.

Rachael H.

5/19/2018

Thanks for the follow up Michael. I am sorry this was not included previously but we do have a helpful article that provides recommendations on how to route a power wire to the battery.

by: John 05/21/2016 One Year Later

2012 Fiat 500

Well made, easy to install and worked perfectly.. We just sold the car and I removed the wiring harness so I can install it in our next fiat.. Highly recommend this product. Mahalo

by: Michael 03/13/2019

2013 Fiat 500

In my case, it arrived securely packaged within the Hidden Hitch box. At the writing of this 'review' - I haven't installed it yet. TBD.

by: Naomi 04/25/2023

2015 Fiat 500

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

by: John 03/29/2025 One Year Later

John One Year Later

3/30/2026

Simple install. Worked as advertised

Andrew N.

3/30/2026

@John Awesome! That's what we want to hear :). What kind of trailer are you pulling?

by: Rick 12/24/2021

It's very easy to hook up I'm glad I bought it works great no problems

by: Kent 03/15/2017 One Year Later

2013 Fiat 500

Good part. I bought this for my van and works well.

by: Robert 07/10/2019

works just like the package says. easy install

by: Halls 06/29/2023 One Year Later

Nice product.

by: Richie 08/08/2015

2012 Fiat 500

easy install, works great!

by: James 03/22/2026

by: Patrick 03/24/2018

2015 Fiat 500

Great

by: Robert 09/15/2021

2012 Fiat 500

true

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

Do you have a question about this Custom Fit Vehicle Wiring?

Trailer Wiring Harness for Fiat 500 and Tail Light Isolating Converter for Trailer 3-Wire System
The Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C56174 will still be what you need for your vehicle. The adapter you need for your trailer will actually be on the trailer side. I recommend the Curt Vehicle to Vehicle Tail Light Converter # C56196 which will separate the combined turn and stop light signals for your trailer function. You will want to use a diode like # 38955 on the tail light function to prevent power feedback.
view full answer...
Cargo Carrier and Light Kit for Class I Trailer Hitch on 2015 Fiat 500
Those are good questions and with a Class I trailer hitch like the Curt Trailer Hitch # C11363 that fits your 2015 Fiat 500 you do need to use a Class I compatible accessory like a cargo carrier. That means could use the Class II Reese cargo carrier you mentioned, but it wasn't designed for it. There is a very similar carrier which will work. Also, to answer your question about the weight of the hitch, it is about 25 lbs. The Curt Cargo Carrier # C18110 is compatible with a Class I hitch...
view full answer...
Is Curt 4-Way Wiring Harness Compatible With 2017 Fiat 500E
That's a really good question, so I checked with Curt for you and verified there are no restrictions on their wiring harness, and it is absolutely compatible with your 2017 Fiat 500E; the harness that fits is the following: - Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C56174 So you can use this harness without any issue with your '17 Fiat 500E, and if you also need a trailer hitch for this vehicle, I went ahead and verified for you that Curt has a hitch...
view full answer...
Curt Receiver Hitch and Wiring Harness for a 2013 FIAT 500 Sport Cattiva
Yes, the Curt Trailer Hitch Receiver Custom Fit Class I - 1-1/4" item # C11363 is a confirmed fit for your 2013 FIAT 500 Sport Cattiva. The Curt Receiver Hitch is a confirmed fit for all models except the Abarth of the 2013 Fiat 500. That receiver's maximum gross trailer weight is 2,000 lbs and the maximum tongue weight is 200 lbs. I recommend the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector item # C56174. This harness plugs inline with your rear tail lights...
view full answer...
Can Curt Plug and Play Flat Tow Wiring and 4-Way Be Installed At The Same Time On 2013 Fiat 500
Since the Curt # C58911 and # C56174 use the same connection points you will not be able to install both at the same time. If you really want to swap them out when you tow/flat tow you can but that is going to be a big hassle. Instead, I recommend using the # C59236 which splices in for installation. It isn't ideal when there is a plug and play option but it will let you keep both installed on your vehicle.
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Trailer Hitch Recommendation for a 2016 Fiat 500X
I checked with Curt and the trailer hitch part # C13271 that you referenced has been confirmed as a fit for all models of the 2016 Fiat 500X so it would work well on your all-wheel drive model. If you wanted to do some towing you might be interested in etrailer ball mount kit # 989900. It comes with 2 ball mounts; one with a 3/4 inch rise or 2 inch drop and one with a 2-3/4 inch rise or 4 inch drop. It also includes a 1-7/8 inch ball, 2 inch ball, hitch pin with clip, and a storage bag. If...
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Wire Colors on the Curt T-Connector Vehicle Wiring Harness Part # C56174
In regards to the Curt T-Connector Vehicle Wiring Harness part # C56174 which is a fit for a 2012 - 2018 Fiat 500 and a 2012 - 2017 Fiat 500 Abarth, the wire colors after the converter are as follows: Green: Right Turn/Stop Light Yellow: Left Turn/Stop Light Brown: Running Light White: Ground The t-connector with the yellow wire will go to the driver side tail light housing and the t-connector with the green wire will go to the passenger side tail light housing.
view full answer...

Do you have a question about this Custom Fit Vehicle Wiring?

Info for this part was:

Written by:

Lindsey S

Installed by:

Jeff D

Updated by:

Wilson B

Updated by:

Hannah L

Updated by:

Kristina F

Updated by:

Isabelle B

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