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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
THIS ITEM IS NOT A FIT FOR
2002 Dodge Ram Pickup
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CURT

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

Part Number: C56225
In Stock
$62.95
Retail:$93.95
You Save: 33%
Custom Fit Vehicle Wiring
Not Confirmed to Fit

2002 Dodge Ram Pickup

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etrailer Installation
We'll connect you with nearby partnered installers who know this exact setup.
Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. T-connector plugs directly into existing wiring. Required relays included. 1-800-940-8924 to order CURT custom fit vehicle wiring part number C56225 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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CURT Custom Fit Vehicle Wiring - C56225

Highlights

  • Custom Fit for Your Vehicle: Works with your vehicle's wiring
  • Tow Without Factory Prep: 4-way connector powers trailer lights for safe towing.
  • Plug-and-Play Install: T-connector plugs into rear bumper harness—no splicing required.
  • Relay-Ready Wiring: Includes jumper harness and relays to activate trailer circuits.
  • Simple Relay Access: Relays mount behind passenger kick panel for quick setup.
  • Upgrade Path Built-In: Brown relay supports 12-volt power if later adding a 7-way plug.

Features to know about

Installs Fast with Factory-Style Plugs: Plug-In 4-Pole Connection

Wiring a trailer doesn’t have to mean splicing wires or figuring out circuits. The Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector plugs right into the factory wiring at the rear bumper. Once connected, it delivers running light, turn signal, and brake light functions through a standard 4-flat plug. No cutting or soldering—just a clean, plug-and-play install.

Activates Tow Circuits on Vehicles Without a Tow Package: Includes Relay Harness

If your vehicle didn’t come with a tow package, this kit takes care of that. It includes a relay harness with three relays that install behind the passenger-side kick panel to activate the trailer lighting circuits. The relays supply power to the running lights, turn signals, and brake lamps so your trailer lights work like they should once the harness is plugged in.

Keeps Wiring Hidden and Protected: Uses Existing Mounting Points

The main plug connects at the back of the vehicle using existing factory points, so there’s no need to drill or run wires through tight spots. The 4-flat connector can be mounted to the hitch using a bracket for a tidy finish that keeps the wiring safe and accessible when you’re ready to tow.

Easily Troubleshoots Lighting Circuits: Relay Placement Made Simple

Everything about this harness is laid out where you can get to it. The relays sit behind the passenger-side kick panel, and the 4-pole connector routes cleanly to the driver-side frame rail near the bumper. If you ever need to check fuses or relays, their locations are straightforward and easy to reach.

Ready for Everyday Towing: Standard 4-Flat Output for Trailer Lights

Once installed, you get a reliable 4-way flat connector that powers your trailer’s running lights, brake lights, and turn signals. It’s the standard connection for small utility trailers, boats, or campers—everything most folks need for everyday towing.

Specs

Electrical Specifications

  • Connector type: 4-Pole Flat Trailer Connector
  • Factory tow package compatibility: For vehicles without factory trailer wiring
  • Relay functions: Includes relays to activate trailer running light circuit, turn signals, and 12V power
  • Relay kit: Contains 1 brown relay (12V power) and 2 blue relays (turn signal/running light circuits)
  • Relay harness location: Passenger-side kick panel area
  • Vehicle end connector: Plug-and-play T-connector
  • Converter: None required
  • Wiring type: Plug-In, Plug and Lead

Diagram showing fuse and relay locations for Curt T-Connector Vehicle Wiring Harness installation on Nissan vehicles, labeled with callouts identifying relay and fuse positions.

Compatibility

  • Vehicle fit: 2005–2021 Nissan Frontier and similar models (Xterra, Pathfinder, Suzuki Equator without factory tow package)
  • Not compatible with: Vehicles already equipped with a factory 4-way or 7-way trailer connector

Installation

  • Installation type: Plug-and-play installation—no cutting or splicing required
  • Front connection point: Passenger-side behind kick panel for relay harness
  • Rear connection point: Driver-side frame rail for trailer 4-way connector
  • Time to install: Typically less than 30 minutes
  • Mounting hardware: Includes zip ties; mounting bracket sold separately

Illustration showing tow package connector location near the rear bumper or frame rail for installing Curt T-Connector Vehicle Wiring Harness on Nissan vehicles.

Included Components

  • 4-pole flat trailer connector:
  • T-connector harness:
  • Relay harness with three relays (1 brown, 2 blue):
  • Installation instructions:
  • Zip ties:

56225 Curt T-Connector - 4 Wire

Compare to Tekonsha 118525

Installation Details C56225 Installation instructions

This Product Fits The Following Vehicles




Customer Satisfaction Score:

Ratings & Reviews

4.8

485 reviews
Review sort icon
Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. T-connector plugs directly into existing wiring. Required relays included.

by:

This was not listed as an exact fit but worked perfect with my 2024 Nissan Frontier. It all plugged into the factory wiring. Made for a very easy instillation.



by:

Worked right away



by:

Everything was on time and fit like a glove. Easy tracking shipment. Well done etrailer



by:

Surprised it came so quickly



by:

Everything fit and works perfectly. Less than an Hour to install and complete the job.



by:

Wiring harness fit my Nissan Xterra perfectly. Took about 15 minutes to hook everything up and the trailer lights all work as expected. Very happy with the harness, relays, and trailer connector.



by:

Everything came as planned. The wiring harness worked perfect. The video made it very simple.



by:

Right part for the right car. Order shipped the day I placed it, arrived earlier than scheduled. Combined with their numerous videos on installation, hard to think of a better service package out there. So easy, so simple. And for less than half what my local parts shop quoted (and didn’t have in stock)
I’ve got three emails confirming order, shipment and delivery.

I’ll be back when it’s time to wire up the Rogue.



by:

The install was very simple - I did not have any issues- and the product performed exactly as expected.



by:

Very simple install, plug and play electrical connections, very simple to use and very good quality product. Very happy it was put on in PA on Friday afternoon and hauled a uhal trailer to GA Saturday morning. Had 0 issues. Definitely a 5 star rating



by:

Hook up was super simple



by:

Great product! Wish I'd bought this first.
I wasted alot of time trying to get running lights on my Nissan Xterra pigtail. I had brake and turn signal only. Excellent customer service- Molly solved problem with this harness. Best of all - she saved me over $200.00 that Nissan wanted just to diagnose problem. If I can install this, anyone can. It only took 10 minutes and I had running lights.
Thank you



by:

easy hook up, with a little utube help..



by:

Perfect fit, works as advertised.



by:

Took less than 20 minutes to install. Hardest part was finding the plug in the kick panel, and putting the trim back on in the cab.



by:

This kit has exactly what my 2015 frontier needed. The pieces are good quality and everything for exactly as it should. The instructions were accurate and I was able to install everything, but some steps were a little vague and a couple of additional pics would have made them more clear. Additionally, a mounting bracket for the trailer connector would be a great addition.



by:

Easy installation... the online videos really helped.
I had an existing harness that was installed with the hitch and the running lights were not working and the shop couldn't figure out the problem!
I removed the passenger side panel and saw the relays were missing. I decided to just tackle the fix myself and it worked out great.



by:

I received my hitch and wiring harness kit for my 2019 Frontier within a few days after ordering. The items were well packaged, and nothing was damaged. The install instructions/video on your website were spot on. I had the whole thing installed and ready to go in less than an hour. Fit and finish of the etrailer hitch is very nice for the price. I would definitely recommend etrailer.com to others.



by:

Got it very quickly. Installed within minutes. Thanks, Guys!



by:

Super easy install! Does the intended job, thanks etrailer!



by:

I have not installed this item yet, but I am sure it is fine. I had ordered this trailer wiring harness from a different seller. After 11 days waiting I cancelled the order and ordered from etrailer on a Monday. It arrived ahead of schedule on Wednesday and was exactly what I ordered, complete, and in good condition. I can't ask for more than that.



by:

The job was exactly as instructions laid out. The customer service was excellent and the items arrived on time.

Mike L. profile picture
Etrailer Expert

Mike L.

4/4/2026

Thanks Tim, I'm glad we could help!



by:

Worked perfectly
Plug and play.



by:

The garage that I go to that fixes our cars said this is the easiest hitch he ever put on. The 4 pole connector was very simple to hook up too.



by:

All of the wires fell out of the gray connector on the Flat 4 wiring while routing the cable. No excessive pulling, they simply fell out upon minimal tension. Curt must have had someone new on the line that day as none of the wires were terminated/crimped properly. The relays worked great and I could use those. Etrailer Customer service has been just a hair above useless since wouldn't even acknowledge the time sensitive timeline I was on and they could not do any express shipping to assist with a replacement, the replacement proceeded to show up 2 days after the expected date, well after my timeline. I sourced the flat 4 harness from somewhere else, returned their replacement along with the defective flat 4 harness. I've requested a refund for the portion I had to source elsewhere via email and hand written note in the return box itself. I simply do not get any response or acknowledgement of the request. What was supposed to be a 30 minute install turned into an afternoon of customer service calls/emails, attempting to fix the harness, sourcing of a backup, anxiety if I'd get everything sorted in time for my trailering needs, revisiting the install with the backup since they couldn't support me with an expedited shipment, a return shipment of the unused replacement that arrived too late, and now I'm receiving "leave a review" emails pretty consistently, so here it is. A review. Faulty Harness and a customer service team that doesn't communicate well or have the ability resolve a time sensitive issue.
I'm thinking I will source my trailering items from somewhere else.


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

  • Troubleshooting Trailer Running Light Circuit of 2018 Nissan Frontier Not Active
    On certain Nissan vehicles like yours an additional blue relay is sometimes needed to activate the trailer running lights circuit. This appears to be the case with your 2018 Nissan Frontier since this circuit isn't active. This is a very common issue surprisingly. For the relay by itself you can use part # 38666-1 and the harness you need to access to plug the relay in is indeed located in the cab behind the panel to the right of the passenger's foot panel. It sometimes can be located...
    view full answer...
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  • Recommended Wiring Harness w/ Relays for a 2023 Nissan Frontier
    That's because the Curt item # C56225 fits the 2005 - 2021 Nissan Frontiers. The correct one for your 2023 Nissan Frontier is the T-One Vehicle Wiring Harness item # 118525 for a 4-Way or item # 118266 for a 7-Way. I have linked a couple of installation videos below for both parts so you can see how to get them set up.
    view full answer...
  • How to Determine if 2005 Nissan Frontier has Tow Package for Installing Trailer Wiring
    The pin needed to install the # 118263 will be on the frame of the truck, but what matters most is whether or not the rest of the tow package wiring will be present. You would need to remove the passenger side kick panel to the right of where a passengers right foot would be. If there is a harness plugged in there that looks like what's picture then all you would need is the # 118263. If not you would need the part # C56225 instead.
    view full answer...
    Image 1 for
  • Trailer Running Lights Not Working on 2012 Nissan Xterra
    The issue is likely the relay for the running lights. The relay is attached to a wiring harness which is located behind the passenger side kick panel near the passenger door (see picture). You should see a harness with 2 blue relays and a larger brown relay. If both relays are there, then the relay is likely bad and should be replaced with the Curt Relay # C57000. If you do not see a harness with relays, then it is likely that the harness wasn't installed. Unfortunately, this harness...
    view full answer...
    Image 1 for
  • Looking for 4-Way Kit that Fits 2022 Nissan Frontier with Relays to Activate Trailer WIring
    Hey Scott, yes the Curt trailer wiring harness part # C56225 that fits your 2022 Nissan Frontier does come with the relays you are looking for to get the trailer wiring completed on your vehicle.
    view full answer...
  • Troubleshooting Trailer Running Light Circuit Not Functioning on Nissan Frontier
    Trailer running lights not working with certain Nissan vehicles is a common problem with an easy fix. There is a relay for the trailer running light circuit that is located in the fuse box (in the cab). If that relay is missing or no longer functions then it can be replaced with one of the blue relays from the Curt Relay Kit # C57000. The relay of the running light circuit on your Nissan Frontier is in the relay harness behind the passenger floorboard kick panel. If you check out the...
    view full answer...
    Image 1 for
  • Are Relays Required to Activate the Trailer Wiring Harness on a Nissan Frontier
    On the Nissan Frontier and other Nissan vehicles, if the vehicle did not come with a factory tow package it will not have a functioning wiring harness even if one, like # 118263, is added. There will be relays that will need to be inserted to make the trailer wiring harness fully functional. If your Nissan did not come with a factory tow package, you would need to use wiring harness # C56225. This harness comes with the relays needed and the wiring required to make everything functional....
    view full answer...
  • Trailer Wiring Harness and Mounting Brackets for a 2016 Nissan Frontier
    We do have a variety of trailer connectors and mounting brackets that you can use on your 2016 Nissan Frontier. If you need a 4-Way Flat connector then the Hopkins # HM43575 will work if you have the tow package. If you don't have the tow package then I recommend the Curt # C56225. You can mount either of these using the Tow Ready # 18144 with a no-drill bracket like part # 18140. I have attached some installation videos and the instructions for you to check out.
    view full answer...
    Image 1 for
  • Installation of 4-Flat Wiring Harness on 2019 Nissan Frontier
    Installation of the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C56225 that fits your 2019 Nissan Frontier (without a factory connector) is very straightforward, but installing a harness on a Nissan does require the use of relays, which are included with this kit. Start the install by attaching the relays, with the blue ones going on the white plugs and the brown one going on the brown plug. Then simply locate where you need to plug in the connectors and that's all...
    view full answer...
  • Availability Of Individual Relays That Come With Curt T-Connector C56225
    Hello Mark, thanks for reaching out. I am sorry to say we do not offer just the relays by themselves. The only way to get them would be with the complete wiring kit part # C56225. This is for a 2005-2021 Nissan Frontier.
    view full answer...
  • Relay Port Location For Trailer Running Lights On A 2015 Nissan Xterra
    Hey Tom, Your Xterra likely just need some relays plugged into the fuse panel located behind the passenger side kick panel. I've attached a short video below where Conner installs the relays from Curt's wire harness # C56225 and will show you how to access the relay location.
    view full answer...
  • Trailer Wiring Recommendation for 2019 Nissan Frontier
    Hey Marvin, for your 2019 Nissan Frontier we have direct fit trailer wiring options like with the Curt part # C56226 for a 7-way or the part # C56225 if you need a 4-way. 7-Way connectors are the round ones and 4-ways are the flat ones you see on smaller trailers typically.
    view full answer...
  • Are Relays Needed to Activate Tow Package Wiring in 2012 Suzuki Equator
    If the 4-pole connector you speak of was factory installed, everything should already be functional. If you've just installed a 4-ploe, using a part like # 118263, then the relay kit # C57000 would be needed. The brown relay activates the 12-volt circuit to the trailer connector (which you won't need since you have a 4-pole) and the two blue relays activate the right and left turn signal and brake lamp. Since you mentioned that you got a signal at the trailer connector with the turn signals,...
    view full answer...
  • Hopkins HM43575 vs. Curt 56225 For 2020 Nissan Frontier
    Hi Carl, The right one will actually depend on if your 2020 Nissan Frontier has the factory 4-way or not. If it does, you'd use the Hopkins # HM43575 as it's simply a replacement for the OEM 4-way. Otherwise, if you don't have any factory trailer wiring on your Frontier and need to add a wiring harness, you'll go with the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C56225.
    view full answer...
  • Trailer Wiring for 2012 Nissan Pathfinder without Tow Package
    Hey Dana, the Curt trailer wiring harness part # C56225 is a confirmed fit for your 2012 Nissan Pathfinder without the factory tow package or trailer connector. This comes with everything needed to activate the trailer wiring as well as provides the 4-way. With just installing what comes with this kit you'd be set.
    view full answer...
  • Towing Relays for a 2022 Nissan Frontier
    I checked with our vendors and the only option to purchase the relay you need for your 2022 Nissan Frontier is to get the Curt T-Connector Vehicle Wiring Harness item # C56225. This includes the necessary relays that Nissan leaves out when building their trucks. However, it does also include the wiring harness. We don't sell the relays separately and I wasn't able to find them online without the harness unless you go through a Nissan dealer. I have linked an installation video below to...
    view full answer...
  • Solution for Trailer Running Light Circuit Not Active on 2019 Nissan Frontier
    This is a very common issue with newer Nissan vehicles like your 2019 Nissan Frontier. There is a missing relay needed to activate the trailer running light circuit. The running light relay can be installed or replaced with # C57000. One likely place for the relay is behind the passenger side kick panel. There could be a harness with 3 relays attached to it. Or it can be behind the dash panel to the left of the steering wheel.
    view full answer...
    Image 1 for
  • Location for Trailer Light Relay on a 2017 Nissan Frontier
    If you have an aftermarket wiring kit for your 2017 Nissan Frontier then the relays for your trailer wiring are located to the right side of the passenger's seat next to the door (see attached photo). I have attached a video of us installing the Curt T-Connector # C56225 on a 2019 Frontier that you can use for reference. For an OEM wiring kit I'm not sure if the relay is in the same location or not. I wasn't able to find anything in the online version of your owner's manual.
    view full answer...
    Image 1 for
  • Recommended Harness and Relays for a 2022 Nissan Frontier
    I checked with Curt and our other vendors and the harness the relays are attached to in the Curt Vehicle Wiring Harness item # C56225 is not available to be purchased separately. You can purchase the relays separately for the 2022 Nissan Frontier with the Curt Relay Kit for Nissan Aftermarket Tow Package item # C57000. I have linked an installation video below to help you get this set up.
    view full answer...
  • Recommended Hitch and Wiring Harness for a 2022 Nissan Frontier
    Yes, the Draw-Tite Max-Frame Trailer Hitch Receiver item # 75282 is a confirmed fit for your 2022 Nissan Frontier. It has a maximum gross trailer weight of 5,000 lbs and a maximum tongue weight of 750 lbs. I have attached an installation video and picture so you can follow along with the install process and see what the final product will be. You're going to need the Curt Wiring Harness with 4-Pole Flat Trailer Connector item # C56225. The connector plugs directly into your Frontier's...
    view full answer...
    Image 1 for
  • Where Are the Relays for Trailer Wiring Plugs on 2019 Nissan Frontier
    I've included the link to one of our installation videos on the 2019 Nissan Frontier that uses the Curt # C56225, which comes with the relays included; these relays can also be purchased with the Curt Relay Kit # 59700. If you fast forward to around the 3:00 mark of the video it shows where the relays are located and how you'll install them, as well as the installation of the 4 way connector. The Hopkins Plug-In Simple Wiring Harness # HM43575 is designed for vehicles that came equipped...
    view full answer...
  • Recommended Trailer Hitch Wiring Harness For A 2023 Nissan Frontier
    The Curt wiring harness # C56225 is not confirmed to fit the 2023 models of the Nissan Frontier, but do I have two options for you to choose from though. Option 1: The T-One Vehicle Wiring Harness with 7-Way Trailer Connector # 118266. This wiring harness is completely plug-in so you won't have to hardwire anything, but it doesn't come with a 4-pole connector so you would need to use an adapter like # 47345. Option 2: The Curt Powered Tail Light Converter with 4-Pole Flat Trailer Connector...
    view full answer...
  • How to Activate Trailer Running Light Circuit on 2006 Nissan Frontier
    There is a relay on your 2006 Nissan Frontier that is either missing (most likely) or not working that controls the running light circuit of the trailer wiring. We see this exact problem pretty frequently on Nissan Frontiers like your 2006 model and it's almost always a missing blue relay. This relay is available in the Curt Relay Kit # C57000. The relay of the running light circuit on your 2006 Nissan Frontier is in the relay harness behind the passenger floorboard kick panel. If you...
    view full answer...
    Image 1 for
  • How to Add 7-Way RV Wiring Harness to 2022 Nissan Frontier
    That you have the Curt Wiring Harness with 4-Pole Flat Trailer Connector, # C56225, is the first needed step. If you have not already installed this, please note the linked installation video below for assistance. The next item needed is the Universal Installation Kit for Trailer Brake Controller, # ETBC7. You will first install the 4-flat, which will power your trailer's lighting, and you'll then plug that into the 7-way that comes with the # ETBC7, which also gives you the wiring,...
    view full answer...


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