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  1. Custom Fit Vehicle Wiring
  2. CURT
  3. 4 Flat
  4. No Tow Package
  5. Trailer Hitch Wiring
  6. Vehicle End Connector
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1957 Jeep CJ-3B
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CURT

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

Part Number: C56338
102 Reviews | 10 Questions
In Stock
$43.94
Retail:$67.95
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 Custom Fit Vehicle Wiring
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1957 Jeep CJ-3B

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curt custom fit vehicle wiring end connector 4 flat c56338
curt custom fit vehicle wiring 4 flat plug-in c56338
curt custom fit vehicle wiring trailer hitch plug-in
curt custom fit vehicle wiring end connector plug-in c56338
curt custom fit vehicle wiring end connector 4 flat
curt custom fit vehicle wiring trailer hitch plug-in t-connector harness with 4-pole flat connector

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2016 mazda cx-9 custom fit vehicle wiring curt trailer hitch 4 flat t-connector harness with 4-pole connector
2016 mazda cx-9 custom fit vehicle wiring curt end connector 4 flat c56338
2016 mazda cx-9 custom fit vehicle wiring curt end connector plug-in c56338
2016 mazda cx-9 custom fit vehicle wiring curt end connector 4 flat on a
2016 mazda cx-9 custom fit vehicle wiring curt trailer hitch plug-in on a

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Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. T-connector plugs into OEM tow package wiring harness. Powered converter reduces strain on wiring system. SMT construction ensures superior performance. 1-800-940-8924 to order CURT custom fit vehicle wiring part number C56338 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 (102)
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CURT Custom Fit Vehicle Wiring - C56338

Highlights

  • Custom Fit for Your Vehicle: Works with your vehicle's wiring
  • Tow Without Factory Prep: 4-way flat connector powers trailer lights for safe towing.
  • Plug-and-Play Install: T-connector plugs inline with tail light harness—no splicing needed.
  • Protected Power Feed: Inline 15-amp fuse on red wire safeguards the converter circuit.
  • Clean Ground Setup: Integrated ground in quick connect eliminates extra grounding steps.
  • Powered Converter Reliability: Built-in module ensures proper signal match to trailer lights.

Features to know about

Installs Without Splicing: Plug-In T-Connector Design

Wiring a trailer doesn’t have to mean cutting into your vehicle’s factory wiring. This Curt T-Connector has a true plug-and-play setup that connects directly to the existing tail light harness. The integrated ground is built right into the quick connect, so there’s no need for a separate ground wire. Once the converter is mounted and the 4-way lead routed to your preferred spot, the harness is ready to go.

Built-In Power Protection: 15-Amp Fuse on the Power Lead

The powered converter is designed with a dedicated fuse holder on the red power wire to protect the circuit. If there’s ever a power interruption, you can easily check and replace the included 15-amp fuse to restore full trailer lighting operation. It’s a simple safeguard that keeps your wiring working reliably every trip.

Ready to Tow: 4-Pole Flat Trailer Connector

The 4-way flat connector gives you the essential lighting functions—running lights, turn signals, and brake lights—so you can safely hook up a small or midsize trailer. It’s the most common trailer connection for basic towing setups and works seamlessly once plugged into your trailer harness.

Clean, Factory-Like Finish: Hidden Powered Converter

Once installed, most of the harness tucks neatly behind interior trim panels for a hidden look. The converter box mounts out of sight and keeps everything organized inside the cargo area. The result is a clean, factory-style wiring setup that’s protected from dirt and damage while still easy to access if needed later.

Specs

Electrical Specifications

  • Connector type: 4-Pole Flat Trailer Connector
  • Converter type: Powered Converter
  • Connector location: Vehicle End Connector
  • Configuration: Plug-In, Plug and Lead
  • Compatibility: No Tow Package

Comparison chart showing Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector alongside similar wiring harnesses, displaying labeled components for reference.


56338 Curt T-Connector - OE Replacement 4-Flat - Surface Mount Technology

Similar to Tekonsha 118278

Installation Details C56338 Installation instructions

This Product Fits The Following Vehicles




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Customer Satisfaction Score:

Ratings & Reviews

4.9

102 reviews
5 Stars
(96)
4 Stars
(4)
3 Stars
(1)
2 Stars
(0)
1 Star
(1)
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by:
After months of searching and the dealer insisting on over $2k to install wiring and reprogram my car I found this. It worked perfectly. It took me maybe five minutes to install (leaving the wiring in the trunk, you can route it under the spare tire, unnecessary for me). Just plugged it in and good to go. Amazing!
by:
2023 Mazda CX-9
Right product in new condition. Best online price point and rapid shipping. Great job (again)! Thank you
Nestor C. profile picture

Nestor C.

4/13/2026

This product has worked out perfectly! The install was easy following the video you provided, The item has a solid build, easily withstanding usage, bad weather and general exposure.

Kate F. profile picture
Etrailer Expert

Kate F.

4/13/2026

@NestorC Glad to hear we had the right fit for you Nestor! What do you mainly use the wiring for?
by:
Excellent fit. Fairly easy install. Wire harness worked like a charm.

One point that makes it easier on the hitch. Be sure to do the two forward holes first.
by:
2016 Mazda CX-9
I couldn't believe how easy this was to install. I had it done in 15 minutes.
by:
Great customer service and quick sipping and great product! Thank you!
by:
2019 Mazda CX-9
This is how wiring should be! Plug it in and use it! Great fit and easy instructions!
by:
2022 Mazda CX-9
Installed with ease. No issues after watching install video.
by:
2018 Mazda CX-9
Perfect fit Ty etrailer
Anthony profile picture

Anthony

11/11/2025

Works great ty

by:
2021 Mazda CX-9
It worked perfectly, as advertised.
by:
Still works as intended.
by:
Online ordering process is a breeze. Fulfillment and delivery times are fantastic. Add customer service with excellent timely updates and you can't go wrong with e-trailer. This is our second time using e-trailer for hitches and both experiences have been top notch five star service.
by:
2022 Mazda CX-9
This is plug-and-play, thanks to the Mazda pre-installed trailer wiring harness connector. Getting to that connector however is a bit tedious, especially if you are not experienced or comfortable disassembling interior trim bits.
One would think that Mazda could figure an easier location for the connector with no extra cost, but that is not a reflection of the design of this kit, except for the fuse location...

Do not forget to disconnect the negative terminal of the battery before starting, and to put the fuse in and test the trailer connector 4 pin signals (any voltmeter will do) before putting back all those interior trim bits.
The kit comes with some butt crimp connectors, a ring terminal and a ground screw which are not needed for a "standard" installation.

(4) rather than (5) stars because the fuse is not accessible once all the trim bits are in place - should have been configured with a longer wire to be easily accessible.
by:
Just plug and go, hardest part was getting at connector in the car
by:
2018 Mazda CX-9
Part got here on time, and fit easily, even easier than the video due (I think) to Mazda putting the ground wire in the connection. All I had to do was put the connector in, then test it. Worked great. My car is a 2018, and the video is for a 2016, but it is the same as far as taking the panels off.
Steve D. profile picture

Steve D.

5/30/2020

Great, no problems.

by:
2017 Mazda CX-9
Ordered a trailer hitch and wiring harness for my Mazda CX-9. Complete order received in just a few days, instructions were accurate and easy to follow, installed both the hitch and wiring harness by myself in 2.5 hours. Very satisfied. P.S. trailer installation video was very helpful.
by:
The wiring harness was easy to install and works great. My only hiccup is that the install video does not exactly match the harness. Mine came with no need to run the ground wire. It is already wired directly into the loom. Also, instead of running the harness through the trunk and leaving it in trunk, I drilled out a plastic grommet next to the car’s harness and ran it out and down the inside of the rear quarter panel.
by:
2022 Mazda CX-9
Etrailer continues to deliver. I needed to add trailer wiring to a vehicle. Went to etrailer, put in the vehicle and searched for the wiring harness. Two options came up with videos on how to install them. Watched the videos, ordered the wiring harness and got it delivered in 2 days. Installed the harness while watching the video and had it done in about 1 1/2 hours. I wouldn’t have had a clue about how to do the installation with out the video and the instructions that came with the harness weren’t helpful. Thanks!
by:
2020 Subaru Outback Wagon
Plug for this device was well hidden behind the rear passenger interior trim. Finally found it but it was not as ‘accessible’ as I would have thought. Grommet under the spare tire is perfect for running the trailer plug through
by:
Item came as described. Installation was made manageable with video instructions.
by:
2019 Mazda CX-9
Pretty straightforward on this one. Exactly as advertised. Instructional video on the website was spot on. Very easy. Lil disassembly, plug in, put back together. Got trailer lights!
by:
The first harness was not made correctly contacted etrailer and was sent a replacement very easy to install
by:
Plug and play! Super easy and clean way to get trailer lights added to car like factory setup.
by:
The videos were super helpful. There was a lot of car trim to take apart, but otherwise the process was straight forward. Just what I needed.
by:
Everything was exactly as advertised. Packaging was tore up due to shipping in a cardboard box. Besides minor scratches on hitch everything was present and intact.
by:
Prompt shipping and delivered as promised. Communication from etrailer.com was fantastic.
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See what our Experts say about this CURT Custom Fit Vehicle Wiring

Do you have a question about this Custom Fit Vehicle Wiring?
  • Installation Video for Curt Wiring Harness on 2020 Mazda CX-9
    Hi Jim; I'm not sure which video you watched originally but the one I linked below shows exactly how to pull back the rear trim panel and access the plug for the # C56338 you purchased. This is the bulk of the installation and the most important part. It is also the only video we have for wiring installation on the 2020 Mazda CX-9.
    view full answer...
  • 4-way Wiring Harness for a 2021 Mazda CX-9
    Your 2021 Mazda CX-9 comes with a factory OEM tow package. Essentially all this is, is a plug in port that allows you to plug in the wiring harness instead of having to splice it into your wiring. Both the T-One Vehicle Wiring Harness for Factory Tow Package # 118278 and the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C56338 will install using that OEM port and provide you with a 4-way trailer connector. While both wiring harnesses are a good option, I...
    view full answer...
  • Where Does the 15-Amp Fuse for the Curt T-Connector Wiring Harness Go?
    I believe the fuse referenced on your Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C56338 is the fuse that goes into the fuse holder on the power (red) wire. I would check there first and see if the fuse has blown which sounds like it may have if all your wiring is good and you're still getting no power. If it has blown, simply replace the 15-amp fuse with another and check for functionality. If you're still having issues after checking this, come back...
    view full answer...
  • Parts Needed to Install 7-Way on 2022 Mazda CX-9
    To install a 7-way on your 2022 Mazda CX-9 you would first need to start with a 4-way like the Curt # C56338 which is a custom fit kit that doesn't require splicing. If the 7-way only needs to support trailer lighting function (not brakes) then all you need to convert it to a 7-way is the part # 37185 which plugs right into the Curt 4-way and is ready to go. If you need to operate trailer brakes the 7-way adapter you'd need instead is the # ETBC7 and a brake controller like the Tow Pro...
    view full answer...
  • Tongue Weight Limit of 2019 Mazda CX-9 With Curt Trailer Hitch C13284
    You are always limited to the lowest-rated component, whether that is your vehicle - in your case a 2019 Mazda CX-9 - or the equipment. So I took a look at the owner's manual of your '19 CX-9 and it says the max towing is 3,500 lbs like you mentioned, but didn't specify a max tongue weight, just that it needs to be 10% - 15% of the trailer weight. So your tongue weight can be more than 350 lbs on your '19 CX-9, and up to 525 lbs with the Curt hitch that fits: - Curt Trailer Hitch Receiver...
    view full answer...
  • How to Connect 2019 Mazda CX-9 to 7-Blade Connector
    Hi Jeannie! You'll want to start by testing the connections on your vehicle and your trailer. The best option is to use a multimeter if you have one, or you can use a circuit tester like Hook Probe Circuit Tester # PTW2993. You should test this on each individual connection on the vehicle side as well as the trailer side to identify where you're losing your power. If the issue is on the trailer's end, you can replace an individual wire or go with a new 7-way connector like Mighty Cord...
    view full answer...
  • Wiring Harness and Hitch Recommendation for 2016 Mazda CX-9
    The term 'Towing Package' is pretty useless because it's an extremely vague description whose meaning varies from vehicle manufacturer to vehicle manufacturer, and even among different models from the same manufacturer. For the sake of this discussion in terms of a wiring harness, Tekonsha uses the term 'tow package' because there is a single, dedicated connector for connecting a trailer harness, rather than installing inline where the factory taillight harness connects to the taillight...
    view full answer...
  • Trailer Wiring and Hitch that Fits 2022 Mazda CX-9
    We have trailer wiring that fits your 2022 Mazda CX-9 with the Tekonsha kit part # 118278 but the Curt you mentioned is not a fit for your vehicle. This will work great with the Draw Tite hitch you plan on installing on your vehicle as well # 76020.
    view full answer...
  • Ground Wire on Curt T-Connector for 2018 Mazda CX-9
    The Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C56338 does not have a separate ground wire outside of the connector. You do not need to find an additional ground you will simply utilize the integrated ground in the quick connect just like the power for the converter. It is simply a plug and play harness. Connect quick connect to vehicle side harness, mount the converter, and run the 4-way to your desired location...don't forget the fuse on the power wire.
    view full answer...
  • Recommendation for Adding a 5 Flat to Activate Surge Brake Reverse Lockout
    To get a 5 flat harness, like # 20036, installed, you will definitely want to be careful while installing. You will need to use a tester, like the # PTW2993, to make sure you are connecting to the correct wire. Once the correct sire is found, splicing is pretty easy with the included quick splice connector. The 60-inch wire also covers just about any vehicle.
    view full answer...

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


Info for this part was:

Employee Mike L
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Mike L
Employee Jameson C
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Edited by:
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Employee Jonathan Y
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