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  1. Custom Fit Vehicle Wiring
  2. CURT
  3. Custom Fit
  4. Trailer Hitch Wiring
  5. 4 Flat
  6. Powered Converter
Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

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

Item # C39DR
Our Price: $74.56
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Custom Fit Vehicle Wiring

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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 C39DR or order online at 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 (1)
  • Q & A (0)
  • Videos (1)
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CURT Custom Fit Vehicle Wiring - C39DR

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

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.


  • 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)
  • Connects quickly and easily
    • Locate connection points behind tail light housings
    • Plug in T-connector
    • Run hot lead to car battery
  • Includes a tail light converter to ensure that your vehicle's wiring matches that of your trailer
    • Powered module connects directly to battery to avoid overloading vehicle's electrical system
  • Constructed using surface-mount technology (SMT) for consistent, reliable performance
    • Maximizes trailer light yield and intensity while producing minimal heat
    • Ensures superior operation in rough road conditions
  • Comes with dust cap for 4-way flat connector


  • Maximum amperage:
    • Stop/turn lights: 3 amps per circuit
    • Tail lights: 6 amps per circuit
  • Limited 1-year warranty


This custom-fit T-connector plugs into your vehicle's wiring harness, which is located behind the tail light housings. You will have to remove interior trim paneling to access these connection points. Once you've plugged in the T-connector, run the hot lead up to your car battery. Connect the lead to the included fuse holder, and then connect the fuse holder to the positive terminal on your battery.

Once installation is complete, the 4-way connector will be stowed beneath your vehicle, near the trailer hitch. A mounting bracket (sold separately) is recommended to keep the connector secure.

It is recommended that you use a small amount of grease on all electrical connections - the plugs on your automobile and the 4-pole connector itself - to help prevent corrosion.

Powered Tail Light Converter with Surface-Mount Technology

A tail light converter is built into this T-connector. This converter is a circuit-protected, battery-powered unit that bypasses the electrical routes that are used by a basic wiring harness. As a result, there is virtually no draw on your tail light circuits.

Because most trailers run on a two-wire system - wherein the brake and turn signals are carried on one wire - the separate brake and turn signals from your vehicle's three-wire system need to be combined so they are compatible with the wiring system of the trailer. This converter combines the brake and turn signal functions of your automobile so that they run on one wire to properly activate your trailer's tail lights. Note: This will not affect how the tail lights on your vehicle operate.

Curt builds each tail light converter using surface-mount technology (SMT). This method of construction 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 circuit board that is smaller yet provides more routing area and that offers superior performance, reliability and durability.

Curt SMT Circuit Boards

Circuit boards constructed using SMT have been shown to 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, leading to increased durability and longer life. In addition, lower levels of resistance ensure better performance, especially for parts that operate at higher frequencies.

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

56479 Curt T-Connector - Surface Mount Technology - 4 Wire

This Product Fits The Following Vehicles

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

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for Review of CURT Custom Fit Vehicle Wiring - Trailer Hitch Wiring - C39DR

Hello everybody, this is Jeff at Today, we're gonna take a look at the Curt T-Connector Vehicle Wiring Harness with the 4-way flat trailer connector. Now, this is a custom fit part, it is designed to fit the 2022 Toyota Corolla Cross vehicles, and on a custom fit part like this, I do like to recommend for you to go to our website, use the fit guide, put in your year and model vehicle, and it'll show you if this will work for your application. Basically, this will provide a nice 4-way flat trailer connector to the back of your vehicle to power your trailer's signal lights. It is compatible with 5-pole, 6-pole, and 7-pole adapters that we do sell separately. This kit does connect very quickly and easily, all you have to do is locate your connection points, which are behind the taillight housing, plug in these T-connectors, one on the passenger's side right here, two on the driver's side, ground's your white wire, right here, and then run this power wire to your vehicle's battery.

Now, if you noticed, it does include this black box, this is your taillight converter, and this is to ensure that your vehicle's wiring will match that of your trailer. It is a powered module, that's why it does connect directly to the battery, and that's to avoid overloading your vehicle's electrical system. This is constructed using SMT technology, which stands for surface-mount technology, for more consistent and reliable performance, it'll maximize your trailer light yield and intensity while producing minimal heat. It also ensures superior operation in any rough road conditions. Now, it does even come with this nice dust cap for your 4-way.

So basically, what you do with this is just attach it to your 4-way, and you can leave it attached if you want, and then when you're not plugged into your trailer, you can just put that cap over those terminals, and it'll protect the terminals from any damage or from the elements. Few specs on this kit, the maximum amperage for the stop and turn lights is three amps per circuit, for the tail and running lights is five amps per circuit. And the last thing I wanna show you is where all these pieces go. But again, you'll basically go on the rear of your vehicle, and then you'll gain access to the back of your taillights. And what you wanna do is start on the driver's side, and this T-connectors will plug into your factory connectors in your taillight housing, there's another set of T-connector that you'll plug in.

Once those are plugged in, you have this white wire here that needs to be grounded, you just connect it to a nearby ground or they give you a screw to make your own ground. Once those are all attached, you can run your extended wire with the 4-way on it out towards the back, and then this black box or this converter, you wanna attach that to a surface, so it doesn't bounce around. You have a tab here that you put a screw in, or again, they include some double-faced tape you can use to mount it. Once those are all connected and this is run out the back, your last one is your passenger's side, and the passenger's side will have the green wire. The way you can tell them apart, the yellow wire would be the driver's side, passenger's side would be a length of wire that's green.

Run this over the passenger's T-connector into the back of the taillights over there. Once that's all done, your last connection is your power wire. Now, your power wire needs to be connected to your vehicle's battery, so this power wire here will run to the front of your vehicle, and they give you extra wires to do that and the connectors. So if you take a butt connector, connect it to one end of this wire, and then run this wire all the way up front to the battery. When you get up to the battery, you don't wanna connect it directly to the battery, you wanna run it through this fuse holder. So you'll take another butt connector, attach it to one side of the fuse holder just like that, and then the other side of the fuse holder you take your eyelet connector and connect that to the battery. Once it's all connected, take your included 10 amp fuse, put your fuse in your fuse holder. Once it's installed, put your cap on there, and now, your system's all ready to go. They do give you some extra cable ties to take up any slack in the wiring, and it does come with a nice set of detailed instructions, that'll show pictures of where all your connections are made. But that should do it for the review on this Curt T-Connector Vehicle Wiring Harness with the 4-way flat trailer connector..

Customer Reviews

Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - C39DR

Average Customer Rating:  5.0 out of 5 stars   (1 Customer Reviews)

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.


Both the heavy hitch receiver and wiring kit came nicely packed, undamaged with all parts necessary. Installation, while a bit complicated to remove the plastic trim, is straightforward on my Toyota Cross, a simple bolt-on swap with the factory steel bumper, eight bolts, and a small trim before reinstalling the plastic cover.


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

  • Correct Curt Trailer Hitch Fit for a 2022 Toyota Corolla Cross
    The correct Curt Trailer Hitch Receiver for a 2022 Toyota Corolla Cross is the part # C64DR which offers a direct bolt-on fit. It has a 1-1/4" opening which can be used for towing or hitch mounted accessories like bike racks and cargo carriers. That said, if you will be towing you'll need to pickup the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part # C39DR and Curt Towing Starter Kit for 1-1/4" Hitches part # C45147. If you're just using the hitch for a...
    view full answer...
  • Curt or Draw-Tite Trailer Hitch Receiver For 2023 Toyota Corolla Cross
    Between the Curt and Draw-Tite hitches that fit your 2023 Toyota Corolla Cross, the better option is the Draw-Tite, which is the following part number: - Draw-Tite Max-Frame Trailer Hitch Receiver # DT28GR The Draw-Tite # DT28GR and Curt # C64DR are similar in most ways, including their concealed look, install, and 2" receiver, but the Draw-Tite's advantage is that it has a 300 lb tongue weight capacity compared to the 200 lb tongue weight capacity of the Curt. That not only speaks to...
    view full answer...

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Info for this part was:

Employee Lindsey S
Edited by:
Lindsey S
Employee Jeff D
Installed by:
Jeff D
Employee Sabrina W
Written by:
Sabrina W

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