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  1. Custom Fit Vehicle Wiring
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  4. Trailer Hitch Wiring
  5. 4 Flat
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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 # C55400
Our Price: $56.65
You Save: 36%
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 C55400 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 (20)
  • Q & A (0)
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  • Why etrailer?

CURT Custom Fit Vehicle Wiring - C55400

  • 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 in rear cargo area
    • 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 driver's-side and passenger's-side interior trim panels in your rear cargo area. 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 in an out-of-the-way location within your cargo area.

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.

55400 CURT T-Connector - Surface Mount Technology - 4 Wire

Installation Details C55400 Installation instructions

This Product Fits The Following Vehicles

California residents: click here

Customer Satisfaction Score:

Customer Reviews

Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - C55400

Average Customer Rating:  4.9 out of 5 stars   (20 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.

2006 Toyota Highlander

Got the hitch that was made for the year and model of our car. It was super easy to install. It bolted right on easy as pie. It is out of the way and looks nice. It is built strong and I am completely comfortable towing with it.
I also got the wiring harness to go with our car. Took a few minutes to remove and reinstall some of the inside panels but was not a problem. The wiring harness connected easy. Fit like a glove. Am very happy with the products. And the service I got was great.

2006 Toyota Highlander

I love it! I've been wanting a hitch on my 2006 Highlander to tow my fourwheeler, and my uncle recommended buying from etrailer. I am very pleased, and I'd definitely order from them again. The hitch and wiring came with instructions but since I had never installed one before I didn't understand them all that well. However I was able to find several videos that made it so much easier. It took me about 4 hours total to install the hitch and the wiring, and they're working great so far!

2007 Toyota Highlander

The trailer hitch receiver and wiring harness a are working great. I am very happy.

The trailer hitch and wiring have been working just fine.Thank you!
Ron - 02/20/2018

2005 Toyota Highlander

Simple "plug n play" harness. The most difficult part was routing the wire from the battery to the back of the vehicle. The instructions were sparse, but now that I've done it once, I know how to do it easier and quicker. All in all took me about 30 minutes.

The existing rubber grommet for the vehicles wiring harness on the firewall of the Highlander has an extra nub that you can cut off to reveal an existing pass through hole. After that be sure that you have removed all of your floor trip pieces ahead of time, and fashion a hook out of a coat hanger and feed it through the trip piece between the doors to pull the wire through. Do the same for the trip piece over the wheel well, and only remove the cup holder panel.

You can also choose to splice the fuse at either end. I'd recommend at the battery end for ease of access. Be sure to crimp the connector to one end of the red fuse wire to connect to the battery, and the other to the black wire.


I gave it a good because it's only been working one day. In ten years I'll give it an excellant.

However, I think I ordered more than I need. I'm not running a lot of lights. But the cost isn't the major issue; it's the time it takes to figure out how to thread the power wire from the battery to the convertor. Really, no help on that subject. You just got to figure it out yourself.

Secondly, there is no video for the C55400. I used the video for the 18something to figure out how to thread the wires from side to side and store stuff. Convertor and yellow wire on the driver side, green on the passenger. It wasn't hard after viewing that.

So, if you're not running a bunch of lights, go with the cheaper one. You don't have to crawl on your back strapping the wire to the undercarriage.

2015 Toyota Highlander

I needed to replace the converter on my Highlander for my trailer lighting. A replacement was sent after supplying the information from my old one which I installed in about 15 minutes. Working wonderfully! These guys rock!

2005 Toyota Highlander

Great product, timely delivery, will now use my trailer safely with the electrical hook up. Convenient to be able to find the wiring for my vehicle and not some generic wiring, plus the instructions are great. Thank you.

2007 Toyota Highlander

Excellent pricing and outstanding service! Instructions for installation make ETrailer #1 source for DIY. High recommendations for everyone! Thank you!

2001 Toyota Highlander

Very simple plug and play on the tail lights, connect your ground wire, and run the power wire up to the battery.


just ordered my second hitch in a week. very easy to order on the phone and both came quickly- very happy


exellent products and quick delevery time.

2003 Toyota Highlander

Products quality seems very good. Very easy to install


Well designed and easy to install!! Great how too video if you needed it, I watched that before I ordered it and was 100% ready when it arrived! Fast delivery!

2006 Toyota Highlander

Extremely easybto use.



Easy to install and works great.


2006 Toyota Highlander



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

  • Can Curt Trailer Wiring Harness # C55400 be Used with LED Trailer Taillights
    The Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C55400 that you referenced works perfectly fine with trailer lights that are LED.
    view full answer...
  • Why Does Curt Trailer Wiring for 2006 Toyota Highlander Require Running Power Wire to Battery
    Not all vehicles can handle the additional amperage draw of the trailer taillights on the vehicle taillight circuits. Those vehicles need a setup that draws power from the battery. Some vehicles have higher rated circuits that can handle this, and others need to have the power drawn straight from the battery to protect the taillight circuits. For your 2006 Toyota Highlander you need to install a harness that draws power from the battery to protect the taillight circuits. For that you would...
    view full answer...
  • Trailer Wiring Recommendation for 2006 Toyota Highlander to Replace Shorted Harness
    Trailer wiring converter boxes are designed to absorb the shorts in trailer wiring and basically sacrifice themselves to prevent your vehicle wiring from getting damaged. That's what happened in your case. That extra wire you mentioned is used for drawing power for the trailer taillights instead of drawing them from the vehicle lights. This is another way it protects the wiring. The part # 118413 does not use a wire like that. Since I prefer that type of install since it's safer I would...
    view full answer...
  • Why Does Curt # C55400 Wiring Harness Require Wire to Battery and Tekonsha # 118413 Does Not
    Some vehicles cannot handle the additional amperage draw of the trailer lights on their taillight circuits, so a wire is required to pull power directly from the battery instead. According to Tekonsha, your vehicle is equipped to handle the extra load, so you would be fine with the Tekonsha T-One Wiring Harness # 118413, especially if you are towing a trailer with just one set of lights at the back and no extra lighting. However, if you are towing a trailer with more than two taillights...
    view full answer...
  • Wiring Kit to Add 4-Way Connector to a 2006 Toyota Highlander
    We do have wiring kits to add a 4-Way connector on your 2006 Toyota Highlander Hybrid that doesn't have the tow package. If you are wanting a kit that plugs in behind the tail lights like the Curt T-Connector # C55400 that you referenced, there are none that connect that way as they involved splicing the wiring in. Out of our available selection I recommend using the Tekonsha # 118413 as we have found that Tekonsha has the most reliable wiring kits. This includes a protected ModuLite and...
    view full answer...
  • Recommended Trailer Hitch & Wiring Harness for 2001 Toyota Highlander
    We offer two sizes/classes of hitch for your 2001 Toyota Highlander that you can see on the linked page. Both 1-1/4-inch Class II and 2-inch Class III hitches are offered; I suggest the 2-inch hitch # C13429 from Curt for its no-drill installation and because there are many more accessories made for this hitch size. An installation video and help article are linked for you. For trailer wiring the correct part depends on how the truck was equipped from the factory and what type of connector...
    view full answer...
  • Which Trailer Wiring Harness for 2007 Toyota Highlander
    The correct trailer wiring harness for your Highlander will depend on whether or not it is equipped with the tow package and the lighting set-up of the trailer you will be towing. If your Highlander has the tow package, and you will be towing a trailer with very basic lighting (one stop/turn/tail light per side) then the Tow Ready # 118248 would be a good choice. If your lighting is a bit more complex, you would need a harness with a higher rated converter like the Curt # C56107. If you...
    view full answer...

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Info for this part was:

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Edited by:
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Written by:
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Expert Research:
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Employee Cole B
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