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  1. Custom Fit Vehicle Wiring
  2. CURT
  3. Custom Fit
  4. Trailer Hitch Wiring
  5. 4 Flat
  6. No Converter
Curt T-Connector Vehicle Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector

Curt T-Connector Vehicle Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector

Item # C56673
Our Price: $29.55
You Save: 34%
Custom Fit Vehicle Wiring

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Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. Connector plugs directly into OEM tow package port - no cutting, splicing or tapping required. 1-800-940-8924 to order CURT custom fit vehicle wiring part number C56673 or order online at Free expert support on all CURT products. Great prices and Fastest Shipping for Curt T-Connector Vehicle Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector. Custom Fit Vehicle Wiring reviews from real customers.
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  • Reviews (39)
  • Q & A (0)
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  • Why etrailer?

CURT Custom Fit Vehicle Wiring - C56673

  • Custom Fit
  • Trailer Hitch Wiring
  • 4 Flat
  • No Converter
  • CURT

Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. Connector plugs directly into OEM tow package port - no cutting, splicing or tapping required.


  • Provides a 4-way flat trailer connector at the back of your vehicle to power your trailer's signal lights
    • Designed for use with a factory tow package
    • Compatible with 5-pole, 6-pole and 7-pole adapters (sold separately)
  • Connects quickly and easily - no cutting or splicing of wires
    • Locate connection point behind rear bumper
    • Plug in connector
  • Includes required relays to activate functions
  • Comes with dust cap for 4-way flat connector
  • Limited 1-year warranty


This custom-fit T-connector plugs into your vehicle's factory tow package wiring harness, which is located behind the rear bumper, at the center.

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 plug on your automobile and the 4-pole connector itself - to help prevent corrosion.

56673 CURT T-Connector - OE Replacement 4-Flat

Installation Details C56673 Installation instructions

This Product Fits The Following Vehicles

California residents: click here

Customer Satisfaction Score:

Customer Reviews

Curt T-Connector Vehicle Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector - C56673

Average Customer Rating:  4.8 out of 5 stars   (39 Customer Reviews)

Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. Connector plugs directly into OEM tow package port - no cutting, splicing or tapping required.

2006 Ford Freestar

The Curt T Connector is as described. It is a perfect fit for the factory 4 pole on my Ford Freestar. Once installed it gave the connection a great "factory" finish look. It was nice to remove the universal installation kit done by Uhaul. Don't get me wrong, it worked, it just didn't look that great as a lot worn was left hanging around and this save me from having to redo it. The only reason this is getting 4 out 5 is due to the poles not being in the correct positions. I had to remove the stops and move the wires into their proper slots. Glad I noticed the colors not lining up, otherwise it would have been a return. As for etrailer... Awesome service!

Its been a year now and the connector continues to work perfectly. Highly recommend this product but as I and others have mentioned in their reviews, double check that the connectors wires are in the proper slot pattern. Its an easy fix and will save you from some frustration on figuring out if you did it right or from having to return it.
LCG - 07/15/2018

2007 Ford Freestar

I looked all over for this wiring harness and guess what etrailer had it, I got it in a very reasonable time by mail. It was so simple to plug up to my 07 Ford freestar it saved me time by not cutting into the original wiring . Thanks.

I haven’t had a problem with it at all, am so glad That your company had exactly what I needed. Works like a charm for my towing needs.
James - 06/13/2018


I Purchased this product for my Ford van along with the hitch. Very simple to install and the instructions were excellent. Installed three relays and two fuses in the fuse box and plugged the pigtail into the existing harness and I was ready to go.

Plugged into the existing harness, is durable and is still working well on different trailers with no electrical hiccups. Great product.
Larry - 08/14/2020

2015 Ford Freestar

Easier to install then you think! Perfect fit for my 2004 Ford Freestar 3.9l. Installed it in one evening by myself. I used a floor jack instead of asking, or paying someone to help install the hitch. People talked about having to use pry bars, and pictured a car lift with an angle drill with a step bit, so I expected the worst. I was pleasantly surprised that no lift was needed, and a regular drill with a regular bit was the only thing needed to drill out the one vertical bolt hole in the frame of the vehicle. No pry bars needed! The other 4 horizontal bolt holes lined up great. Made use of the fishing wire on 3 out of 5 bolts. Everything was included with the hitch - all the locking washers, nuts and bolts. Sorry, I didn't take the time to snap any pics. Basically started out by bolting one side up with one bolt and then the other side. Tightened up the 4 horizontal bolts, after that I drilled out the vertical bolt hole. Fished the fifth bolt through the hole and bingo! Installed in about 2 hrs. with my 2yr olds help. Lol. After he relocated the nuts and bolts...loved every second of it! Could have possibly done it in 15 minutes with a lift.

2004 Ford Freestar

I give e-trailer 5 stars. My 1st ford freestar, the trailer wire harness was spot on. The video was perfect. I changed vehicles to another ford freestar. The hitch was reinstalled. The wire harness did not match the light sockets. That was driving me crazy! I finally returned back to e-trailer. Looked at another harness, video, and under my vehicle. I had a trailer harness connector under my bumper. E-trailer was spot on! The new harness and fuses were installed in 5 minutes. Yep, I am a lady and with the help of the videos the harness were easy to install. :)


I finally got the product to work, but it cost me countless hours of hassle and further expense to have a mechanic figure out that it was the wiring of the plug that was incorrect from the factory. During the trouble-shooting process, I bought new wiring for the trailer, new lights, new relays, and new fuses, but all of that was unnecessary, because the problem was in the wiring of the brand new plug on the product. Once the wiring was corrected, the product worked fine, and it has worked fine every since.


Excellent product! Shipped with the trailer hitch (which arrived sooner than I'd anticipated - YAY). Install was less than 10 minutes, hooked it up and tested with my trailer and everything worked perfectly right out of the gate. Even though the picture shows a small bundle of zip ties in the package, none were actually included with the products. (Not a problem, I keep a package of zip ties in my toolbox, but I'm just sayin...) If that's my biggest problem today, it's gonna be a good day!


Great service, product was as-advertised, installation video was spot-on. I will absolutely order from etrailer again.

Product is working great. I will purchase my next towing accessory at etrailer too.
Paul K - 01/30/2019

Ford Freestar

Great price for exactly what I needed. The Freestar already had the wiring in place, but this kit provides the relays and fuses needed to put power to the connector. This kit is a great price considering Ford wants about $15 per relay.


This is the easiest wiring harness to attach, make sure that you're vehicle has the factory towing option which includes the electrical connector in the rear. Install the relays and 2 fuses, couple of ty raps and its done. I love this package. Shipping went pretty quick as well.


Everything was plug and play. Installed fues and relays. Plugged the trailer wire connector in and to trailer. Bingo everything works right the first time. I like when things go right.

2006 Ford Freestar

Etrailer is absolutely the best mail order place ive ever done buisseness with they are fast shipping and really care about the customer satisfaction and great prices too and george even follows up with u on the order

2005 Ford Freestar

Outstanding customer service from Simple install , Looks and works great. Very happy customer. E-Trailer.Com Is the place for all your trailer needs, Thank you, Scott customer for life.

2004 Ford Freestar

It's amazing


It works and fit just like I expected , use it weekly , couldn't ask for anything better, thank you for your wide variety of service and products

2004 Ford Freestar

Everything came quickly and was in good condition. The installation video on the website was very helpful as well. I'm happy:-)


Worked great. Easy install

2004 Ford Freestar

I really like your products. I have bought from you before, that is why I have returned.
Thank you for your fast service and your great products.


Works well. Too bad I had to pay for relays and fuses that my vehicle already has. I wish Curt offered a version that was just the pig tail. I'll keep the relays for some scientific project, like making a Frankenstein monster or something.

2004 Ford Freestar

Easiest installation of my life, no cutting, plug and play.


Fast shiping. Hitch wiring was easy to install!

2004 Ford Freestar

Awesome!! Never had one so easy to install. Very good instruction and installation was a breeze!!


Install took like five minutes- fantast ic!!

2005 Ford Freestar

Very easy instulation on the 2005 Ford Freestar. Recommend this lit if unsure if you don't have relays and fuses in fuse box. Has to be cheaper than Ford dealer.


fast delivery,came with good instructions, easy install

Show More Reviews

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

  • Trailer Wiring Plug Location to Install Wiring Harness # C55673 on a 2006 Ford Freestar
    The plug on a 2006 Ford Freestar to install the Trailer Wiring Harness, # C56673, can be located behind the rear bumper near the spare tire. The plug should be connected to a gray protective cover mounted to the back of the bumper. If you see the cover but not the plug, it may be above the spare tire. This harness is designed for those vehicles that came with a factory tow package. I have included a link to the installation instructions for reference.
    view full answer...
  • Trailer Wiring Recommendation for a 2006 Mercury Monterey with Tow Package Port
    If the port on your 2006 Mercury Monterey is present but not active that just means that the included relays that come with the # C56673 are needed. The relays are what activates the circuits so that would explain why the connector does not have voltage. I attached an install video for this harness for you to check out as well.
    view full answer...
  • Trailer Wiring with Relays Recommendation for a 2004 Ford Freestar
    The only way I can recommend for you to get the 3 relays you need for your 2004 Ford Freestar is to get the Curt trailer wiring harness part # C56673 as it includes them. I attached an install video for this harness as well on a 2004 Ford Freestar as well.
    view full answer...
  • Diagnosing and Repairing Wiring Problem on Trailer Towed by 2006 Ford Freestar
    In a situation like this, where you seemingly have ruled out the trailer as being the problem, I would recommend trying the vehicle with a different trailer, if you can borrow one from a friend or neighbor, you can quickly and easily determine if the problem exists with the tow vehicle or with the trailer. If you try a borrowed trailer, and all the lights work fine, then the problem is on your trailer. If the lights on the borrowed trailer do not work correctly, you have isolated the problem...
    view full answer...
  • Troubleshooting 4-Way Wiring on 2006 Mercury Monterey with No Power
    I spoke to my contact at Curt and he told me that if you have all of the correct fuses and relays installed on your 2006 Mercury Monterey and the receptacle that the 4-way harness of the part # C56673 plugs into still doesn't have power you will want to trace that harness back to see if that harness is connected properly. If it is connected there is still something that's missing between the trailer wiring circuits in the fuse box and the trailer wiring. If this is outside of your wheelhouse...
    view full answer...
  • Troubleshooting Running Light Circuit of Curt Trailer Wiring # C56673 Not Functioning
    Have you tried swapping the relays of the Curt # C56673 around that you installed with the harness? Easiest way to determine if a relay is blown is to replace it with a known working one. A short on your trailer wiring could have possibly damaged it or it was defective.
    view full answer...
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  • Is the Screw Included With Wiring Harness C56673 Necessary on 2007 Ford Freestar?
    I spoke with a representative of Curt who told me that the screw that is included with the Curt T-Connector Vehicle Wiring Harness # C56673 that fits your 2007 Ford Freestar is not needed and it can just be thrown out. Usually a screw like this is included so it can be used for the ground wire, but # C56673 plugs in (see linked installation video) so why it was included with this kit is anybody's guess.
    view full answer...
  • Do Tail Lights Operate Normally After Installing Curt T-Connector # 56073 in 2004 Mercury Monterey
    The part you referenced, Curt T-Connector # 56073 for the 2004 Mercury Monterey, is a correct fit for vehicles that came equipped with the factory tow package. It plugs in under the vehicle's rear at the center. If your Monterey does not have the factory tow package you will instead use TowReady harness # C56673 which comes with the needed relays to get everything working. With either of these trailer harnesses installed your Monterey's tail lights will behave normally whether or not...
    view full answer...
  • 4-Pole Trailer Wiring Harnesses for 2004 Mercury Monterey
    If your 2004 Mercury Monterey has the 3 relays and 2 fuses installed then chances are good that it also has the tow package plug-in connector to mate with 4-pole harness # 56073. But if you are not sure you can still install a 4-pole harness by using kit # C56673. This harness comes with the needed relays to activate the plug on the back of your Monterey. This 4-pole harness will provide stop, turn and tail light signals for a 4-pole-equipped trailer.
    view full answer...
  • Left Turn Signal Makes Lights Flash and One tail Light Works when Connected to 2007 Ford Freestar
    It sounds like there is a ground and/or connection issue on the trailer or an issue inside the converter box on the vehicle but there are ways to determine if that is the case or if the harness for your 2007 Ford Freestar is the problem. First, disconnect the trailer from the vehicle. Then use a circuit tester, such as # PTW2993, to test the 4-Way connector while someone sits in the vehicle and operates the lighting functions. If the 4-Way end does not have the right signals when testing...
    view full answer...
  • Recommended Wiring Harness for a 2005 Ford Freestar
    If you have a wiring harness that was installed by splicing into your 2005 Ford Freestar's wiring then that would be the problem. The owner's manual for your Freestar states not to splice into the wiring because it can cause malfunctions. There are two options for you to install a wiring harness on your Ford Freestar without a factory tow package that does not involve splicing. To figure out which one you would need all you have to know is if your Freestar model has the plug behind the...
    view full answer...
  • Hitch Recommendation for a 2004 Mercury Monterey for Towing Small Trailer
    I would recommend the Curt Hitch part # C13587 for your 2004 Mercury Monterey. This is a Class III hitch with a 2 inch opening confirmed to fit your vehicle that may frame hole enlargement. Drilling doesn't necessarily add anything to a hitch's value, basically it's just an extra step that some hitches require. With this hitch sometimes the vehicles frame holes don't line up for the hitch to attach to so you have to enlarge the hole to compensate for that. I attached an install video for...
    view full answer...
  • Hitch and Trailer Wiring Recommendation for 2006 Ford Van Freestar
    For your 2006 Ford Freestar I would recommend a Class III hitch like the part # C13587 as it would have more than enough capacity which would be useful for the towing you plan to do. The # C13587 has a 350 lb tongue weight and 3,500 lb total trailer weight rating. As long as the weight of everything you plan to tow plus the weight of the trailer is less than that you should be good to go. Class III hitches also allow more flexibility for future hitch accessories like bike racks and cargo...
    view full answer...
  • Trailer Hitch and Towing Accessories Recommendation for 2006 Ford Freestar
    The Draw-Tite Class III # 75158 and the Hidden Hitch # 87107 were both manufactured by the same parent company, Cequent Performance Products. The manufacturer has since discontinued the Hidden Hitch option. The Draw-Tite and Hidden Hitch were nearly identical items. The only difference between the two was the label with the brand name. Since you'll be towing with the hitch, you might be interested in the following to complete your towing system: -Trailer wiring harness, part # C56673...
    view full answer...
    Image 1 for
  • No Power to Curt T-Connector Harness # 56073 Installed on 2005 Ford Freestar
    The Curt T-Connector Vehicle Wiring Harness # 56073 referenced in your question is confirmed to fit your 2005 Ford Freestar only if it has the factory tow package. If you aren't getting any power at all to the connector then it's very possible that your vehicle is not equipped with the needed tow package wiring to power the factory connector behind the rear bumper so you'd need to go with # C56673 instead. You can try testing the factory connector on the Freestar with the Curt harness...
    view full answer...
  • Trailer Hitch Receiver and Vehicle Wiring Harness For a 2005 Mercury Monterey Premier
    The Curt Trailer Hitch Receiver # C13587 is confirmed to fit all trim levels of you 2005 Mercury Monterey. This custom fit class III receiver is rated for maximum capacities of 3,500lbs towing and 350lbs of tongue weight. If you use a weight distribution hitch maximum capacities increase to 5,000lbs towing and 500lbs of tongue weight. For towing small trailers you will need one of 2 wiring harnesses. If your Mercury has the plug for a factory towing harness behind the bumper you will...
    view full answer...
  • Class III Trailer Hitch for a 2006 Ford Freestar
    For your 2006 Ford Freestar I recommend going with the Curt # C13587 as we've found that the powder coat finish on the Curt hitches tends to be thicker and hold up better against chips and scratches. Installation will involve removing the exhaust from the rear most exhaust hanger to gain access to the hitch mounting holes in the frame and you may have to slightly enlarge the frame holes if the hardware doesn't fit, but if you look at the video I have linked to and fast forward to the...
    view full answer...
  • Will The Draw-Tite Trailer Hitch # 36318 Fit All Years of Ford Freestar
    The item you selected, Draw-Tite Trailer Hitch, part # 36318 will fit all model years of the Ford Freestar which range from 2004-2007. This hitch will also fit the 2004-2007 Mercury Monterey. To complete your towing setup, you will need the following items: Draw-Tite Ball Mount, part # 36071 1-7/8 Inch Hitch Ball, part # 19256 2 Inch Hitch Ball, part # 19258 Pin and Clip, part # PC2 For wiring, if your Freestar came equipped with a factory tow package, you will need Curt Custom Fit Vehicle...
    view full answer...

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Info for this part was:

Employee Mike L
Expert Research:
Mike L
Employee Michael H
Expert Research:
Michael H
Employee Jameson C
Expert Research:
Jameson C
Employee Joshua S
Video Edited:
Joshua S
Employee Cole B
Installed by:
Cole B
Employee Wilson B
Updated by:
Wilson B
Employee Kristina F
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