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1990 Ford Ranger
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CURT

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

Part Number: 56090
24 Reviews | 7 Questions
In Stock
$78.59
Retail:$138.95
You Save: 43%
 Custom Fit Vehicle Wiring
Not Confirmed to Fit

1990 Ford Ranger

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curt custom fit vehicle wiring 4 flat plug-in t-connector harness with 4-pole trailer connector
curt custom fit vehicle wiring trailer hitch 4 flat t-connector harness with 4-pole connector
curt custom fit vehicle wiring end connector 4 flat 56090

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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 56090 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 (24)
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CURT Custom Fit Vehicle Wiring - 56090

Highlights

  • Custom Fit for Your Vehicle: Works with your vehicle's wiring
  • Tow-Ready Lighting: 4-pole flat connector powers trailer turn, brake, and tail lights.
  • Plug-and-Play Install: T-connector plugs behind tail lights, no cutting or splicing needed.
  • Reliable Signal Match: Converter ensures vehicle and trailer lights work together correctly.
  • Clean Wire Routing: Uses existing grommets for a tidy, protected wire path.
  • Solid Grounding: Dedicated white wire ground improves signal consistency and safety.

Features to know about

Installs Fast Without Cutting Wires: Plug-In T-Connector

This Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector plugs directly into the vehicle’s existing tail light wiring. There’s no need to cut or splice factory wires, which keeps the install quick and clean. The harness connects right behind the tail lights, so you spend less time running wires and more time towing.

Clean Routing Through Factory Grommets: Protected Wiring Path

The harness routes through existing grommet holes behind the tail lights. You can pull out each grommet, make a small slit, and pass the 4-way connector and green wire through without drilling new holes. Once re-seated, the grommets help seal out dirt and moisture and keep the wiring tucked neatly out of sight for a factory-style finish.

Reliable Power Converter for Trailer Lights: Stable Signal Transfer

Built with a powered converter, this harness supplies the correct current to your trailer lights while protecting your vehicle wiring. It delivers the four standard lighting functions—green wire for right turn and brake, yellow for left turn and brake, brown for taillights or running lights, and white for ground—ensuring steady light operation during towing.

Covers Basic Trailer Lighting Needs: 4-Flat Connection Ready to Tow

The 4-flat connector gives you everything needed for most small trailers—running lights, brake lights, and turn signals. Once installed, you can hook up the plug and hit the road knowing your trailer lighting is working properly with your vehicle’s system.

Specs

Wiring Functions

  • Green: Right Turn and Brake Lights
  • Yellow: Left Turn and Brake Lights
  • Brown: Taillights or Running Lights
  • White: Ground

Comparison chart showing Curt and other trailer wiring harness connectors with labeled callouts for wire positions and connector types, illustrating differences in 4-way flat trailer connectors for various vehicle applications.

56090 CURT T-Connector - Surface Mount Technology - 4 Wire

Similar to Tekonsha 118585

Installation Details 56090 Installation instructions

This Product Fits The Following Vehicles






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Customer Satisfaction Score:

Ratings & Reviews

4.8

24 reviews
5 Stars
(20)
4 Stars
(3)
3 Stars
(0)
2 Stars
(1)
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by:
2010 Ford Transit Connect
Received my wiring harness along with my hidden hitch from Etrailer. Very happy with the yow assembly but the wiring harness was a little more difficult to install then I thought. On the 2010 Ford Trandit connect XLT right rear tail light assembly has no access point to run the harness thru so you have to remove the rear passenger side tire and fender well Caling to be able to drill a 1" hole thru the wall that access the tail light assembly. This is time consuming let along if you don't have a drill or large enough but to drill with them your screwed. Luckily I had the tools for the job. Another customer might not be so fortunate. I think some Ford Transits are different when it comes to the passenger side rear tail light assembly (rubber Grommet) access, others might have the access point so you don't have to spend 2 + hrs to install. All in all I'm very pleased how it turned out.
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by:
2010 Ford Transit Connect
I was disappointed with this item, and expect more from Curt. Unlike the more expensive brand, there are no plug connections on the wires on the flat 4 so it won't fit through the driver side opening to pass to the passenger side. I had to cut the four wires and then butt connect on the underside of the vehicle. Had to make a trip to the auto parts store for heat shrink but connectors, and put in the extra time. Instructions were also lacking on where to feed the wires out of the taillight bucket. Decide if you have more time than money when thinking about purchasing this item.
by:
The trailer wire harness assembly fit perfectly. Not confusing to install, either. It wouldn't work without connecting the converter to the battery so I had to connect that and string the wire along the frame all the way to the back to make it work right. No problems at all.
by:
2016 Mercedes-Benz Sprinter 3500
This was an easy installation. I say that as someone who has experience with electrical wiring and hiding wires. I would say difficulty is about a 3 in the real world. The included instructions are good enough and photos are accurate.
by:
2011 Ford Transit Connect
What a great product. Easy installation, watch a few vids on how to do it. Took me 1 hour to do it by myself with help of some Jack stands and Jack.
by:
2012 Ford Transit Connect
your battery, consider using the rear 12volt power source if you have one. My Transit was a Wagon version and did have one.
by:
Good price and fast shipping. Product fixed what our local U-haul trailer shop couldn't figure out.
by:
received the wiring harness quickly and it was in good condition waiting on a little warmer weather to install it
by:
Perfect solution for our service van! Excellent product and easy to do!
by:
2012 Ford Transit Connect
a couple of days from my order. I was very pleased with the speed of the shipment. I haven't installed the kit yet, but it looks fine and I anticipate it will mork great.
by:
as described fast shipping,
by:
2013 Ford Transit Connect
Very simple instructions
by:
This was super easy to install. If I didnt have to run a hot from the Batt. it would have only taken 30 minutes.
by:
that I purchased from
Etrailer. I have already completed the instalation. Again every thing
fit perfect. Thanks again for a quality product

Leonard
by:
Great product , easy to install.
by:
worked as advertised.
by:
was the correct part I needed
by:
great stuff, well planned
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2010 Ford Transit Connect
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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?
  • Trailer Hitch and Wiring Recommendation for 2010 Ford Transit Connect
    The Curt hitch part # 13076 is a confirmed fit for your 2010 Ford Transit Connect and would be a great option. It has plenty of towing capacity at 3,500 lbs total trailer weight and 350 lbs tongue weight plus the hitch is made in America. Since 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...
    view full answer...
  • Left Turn Signal Not Working on Curt Vehicle Wiring Harness for 2013 Ford Transit Connect
    It sounds like an intermittent ground problem that is potentially causing both issues. What I recommend is to try moving the converter box ground to a different location. You may need to scrape away paint to get to bare metal for the best ground. Also make sure that the fuse in the power wire is fully inserted and that nothing is pinching any of the converter box wires. I have also included a link to troubleshooting wiring for you that should also help.
    view full answer...
  • How to Remove and Re-Install Wiring Harness Grommets on a 2010 Ford Transit Connect
    The grommets you are inquiring about are located inside the sheet metal hole behind the vehicle tail lights. You will need to remove the grommet on both sides of the vehicle. On the drivers side pull the grommet out, using a dull edged object to help un-seat the grommet, and make a slice in it, being careful not to damage the existing wiring, large enough to route the 4-Way connector and green wire down through. On the passengers side pull the grommet out and route the green wire up through...
    view full answer...
  • Is Exhaust Lowered To Install Draw-Tite 75678 Class III Trailer Hitch on 2010 Ford Transit Connect
    According to the installation instructions, lowering the exhaust isn't required during the installation of the Draw-Tite # 75678 on a 2010 Transit Connect. The instructions do call for the spare tire to be lowered to gain access to the frame and then raised back up into position after the install is complete. Installation of the Tekonsha Custom Fit Vehicle Wiring, part # 118585, is not too bad. The unit simply plugs into the factory connectors of the tail lights on each side of the vehicle...
    view full answer...
  • Comparing the Curt T-Connector 56090 and Tekonsha T-One 118585 for a 2010 Ford Transit Connect
    The Curt T-Connector Vehicle Wiring Harness part # 56090 and the Tekonsha T-One Vehicle Wiring Harness part # 118585 are both fits for your 2010 Ford Transit Connect. They are essentially two different manufactures version of the same product. The purpose is the same as well as the install. The only difference is really in terms of quality and that edge goes to Tekonsha as we have less issues with the T-One than we do with the T-Connector but both will work just fine for you. I have attached...
    view full answer...
  • Why is the Reverse Safety Switch not Deactivated when Trailer Connected
    The Curt Wiring Harness # 56090 supplies a 4-way flat connection point for the trailer connection. The functions of these wires are: Green - Right Turn and Brake Lights Yellow - Left Turn and Brake Lights Brown - Taillights or Running lights White - Ground This wiring harness does not provide a wiring option for detection or sending a reverse signal. I have included a link to one of our helpful articles about trailer wiring diagrams and vehicle connectors for your reference. To disable...
    view full answer...
  • Trailer Wiring Harness Options for a 2010 Ford Transit Connect
    The Curt trailer wiring harness, # 56090, is a fit for a 2010 Ford Transit Connect. I have included a link to the installation instructions for you. If the vehicle came with a factory tow package, the correct wiring harness is # 118585. I have included a link to the installation instructions for this harness as well.
    view full answer...

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Info for this part was:

Employee Robert G
Expert Research:
Robert G
Employee Michael H
Expert Research:
Michael H
Employee Rachael H
Expert Research:
Rachael H
Employee Wilson B
Updated by:
Wilson B
Employee Kristina F
Updated by:
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Employee Isabelle B
Updated by:
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