bing tracking image
  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
2017 Mercedes-Benz Metris
etrailer Installation
We'll connect you with nearby partnered installers who know this exact setup.
CURT

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

Part Number: C56378
In Stock
$53.69
Retail:$88.95
You Save: 40%
Custom Fit Vehicle Wiring
Not Confirmed to Fit

2017 Mercedes-Benz Metris

Will this fit?

To see if this custom-fit item will work for you please tell us what vehicle you'll use it with.

zoom in icon
slider vertical icon
zoom out icon
Comment field cannot be left empty.
Name field cannot be left empty.
By submitting this form, you understand and agree to our Terms of Sale, Website Terms of Use and Privacy Policy.

Thank you! Your comment has been submitted successfully. You should be able to view your question/comment here within a few days.

Error submitting comment. Please try again momentarily.

Product Images

In Use/Installed

Customer Photos

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. 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 C56378 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.
  • All Info
  • Reviews (387)
  • Q & A (0)
  • Photos

CURT Custom Fit Vehicle Wiring - C56378

Highlights

  • Custom Fit for Your Vehicle: Works with your vehicle's wiring
  • Tow Without Factory Prep: 4-flat connector powers trailer lights for safe towing setup.
  • Plug-and-Play Install: T-connector plugs behind interior trim with no wire cutting.
  • Power Converter Protection: Built-in module isolates vehicle wiring from trailer load.
  • Backup Camera Ready: Extra white connector keeps camera system working correctly.
  • 7-Way Upgrade Option: Works with ETBC7 kit to add brake and charge functions later.

Features to know about

Installs Clean and Simple: Plug-In Behind the Trim Panel

There’s no need to cut or splice wires with this harness. The Curt T-Connector plugs right into existing factory connectors behind the driver-side trim panel. Once connected, it gives you a 4-pole flat trailer plug that’s ready for your trailer’s signal lights without altering your factory wiring.

Keeps Factory Features Working: Pass-Through Connection for Backup Camera

Many vehicles use the same rear wiring harness for added features like backup cameras. This Curt harness includes an extra white quick-connect lead that keeps those systems working while still delivering power to your trailer lights. It’s designed so everything continues to operate as it should after installation.

Reliable Power for Trailer Lights: Powered Converter Protection

The built-in powered converter isolates and protects your vehicle wiring from the draw of the trailer lights. It supplies consistent power to running, turn, and brake lights, helping prevent overloads or signal interference on the vehicle side.

Ready for Towing Upgrades: 4-Way Flat Connector Compatibility

The 4-way flat plug gives you standard trailer lighting functions and easily pairs with a 7-way adapter when you’re ready to add a brake controller or charge line. It’s a solid foundation for everything from small utility trailers to more advanced towing setups.

Specs

  • Comparison diagram of Curt vehicle wiring harnesses showing labeled connectors and converter modules for trailer wiring applications.

56378 CURT T-Connector - Surface Mount Technology - 4 Wire

Replaces Curt C56118

Similar to Hopkins HM11143114 and Tekonsha 118521

Installation Details C56378 Installation instructions

This Product Fits The Following Vehicles




Customer Satisfaction Score:

Ratings & Reviews

4.8

387 reviews
Review sort icon
Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. Connector plugs directly into existing wiring. Powered converter reduces strain on wiring system and is made using SMT to ensure superior performance.

by:

I was t-shooting a dealer install of a hitch/harness on my 2008 Odyssey using etrailer's very helpful information. After some time I ruled out the obvious fixes and narrowed it down to the harness but nothing specific. This harness replaced the other and it has performed flawlessly since.

A. M. profile picture

A. M.

10/5/2022

I have not had any issues with this harness since installation and it has been several trips to the lake and down to FL.



by:

Quick and easy installation.



by:

My Curt wiring harness shipped quickly and worked fine when I installed it. I thought it was expensive but then it had molded connectors so I'm sure that drives the price up. The instructions could have been better.....left me guessing a few things but that's no reflection on etrailer.....they're great.

Charles profile picture

Charles

3/14/2019

Still happy



by:

Product arrived on time and as promised. Installation was a snap. Instructions included with the product for installation into my 2011 Honda Odyssey were OK, but a bit light on details for removing the scuff panel and rear side panel prior to installation. Fortunately, I viewed a video on etrailer.com that showed installation on a 2012 Odyssey that clearly showed what to do to remove the panels from the van. This was absolutely fantastic knowledge that helped me, a first-timer in this sort of thing, gain the confidence I needed to do the work. Thanks go to the etrailer.com folks for their online info like this! I will point out that I had the advantage that I was changing out a dealer-installted defective unit, so I could see basically what the final install was supposed to look like. Bet even without that, this would have been easy because of the info at this site.

Steve W. profile picture

Steve W.

6/4/2014

Everything is still working just great. I will comment that with the new LED trailer lights I installed about the same time, when the van is turned off and the trailer is still plugged in all the trailer lights glow very dim only notice it when it is dark out. Not sure if this is a wiring issue on the trailer or what, and it seems to do no harm.

Rachael H. profile picture
Etrailer Expert

Rachael H.

6/6/2014

Thanks for your reply. It is is not uncommon for the Curt Powered T-One Wiring Harness to allow a small amount of power through. If you were using incandescent lights this small amount of power draw would not be enough to illuminate them,. But since you are using LED lights which require very little voltage, you are noticing it. As you said this is not a big deal, just be aware of your vehicle battery power levels and check it often. Especially if you will have the trailer plugged in and drawing power for an extended period of time.


by:

Let me tell you a story....my husband, two young children, and myself just moved from Maryland to Florida during a pandemic. Talk about stressful. Couple that with the fact that my son is high risk, my husband was starting a new position at Eglin, AFB, I myself am teleworking full time, and everything that COULD go wrong with our move DID go wrong. I found out three days before we were to DEPART that the trailer hitch I ordered through a local mechanic arrived with the WRONG WIRING HARNESS. For this move my famiy and I had a real tight timeline to get down to Florida...real tight. Having no wiring harness to pull the 5x8 trailer meant near disaster (what were we pulling might you ask? A trailer full of my dearly departed father in laws tools...like 1,500lbs of SENTIMENTAL TOOLS). I called e-trailer in a panic... pretty much full on panic and the LOVELY man I spoke with assured me that 1. they had a wiring harness that would fit my 2016 Honda Odyssey and 2. It would arrive in time for us to install and depart. I'm going to admit I was skeptical. VERY skeptical but I gleefully paid and thanked the gentleman I spoke with. NAY TWO DAYS LATER the harness arrived EARLY!!! We installed it EASILY and without issue (I can update with pictures later but...it looks like a wiring harness) stuffed our minivan full of kids and crap and slapped the trailer on the back of it. We made our 15 hour drive to our new home (aside from the fact that my children are terrible in the car and pretty much scream puked the entire time) easily. I am seriously impressed with the customer service I received AND the excellent pricing (although to be honest I would have paid WHATEVER to get the darn thing on time). I cannot recommend this company and this part (seriously easy to install...I did it with a 3.5 year old clinging to my leg, a 6 year old blaring the horn and a very tired husband observing). ANYWAY thank you e-trailer y'all really are the best.

Carrie P. profile picture

Carrie P.

12/8/2021

Everything worked great for our move and continues to work perfectly!



by:

This really was a piece of cake to install after watching the video. I used the same grounding bolt they found.



by:

Thanks. Excellent service



by:

Plug and play. Seems to work!



by:

Perfect Kit! Everything I needed was in cluded.



by:

The wiring harness works great. After pulling off the plastic panel in the van, it was a simple plug and play process.



by:

Install was easy. Received on time. Have not had to use it yet. If all work well this would probably be a five star review.



by:

Once the wiring harness arrived, it was installed in less than 20 minuets. Tested it out on the trailer and everything worked great. If I need sports in the furture, this is the first place I’ll look.

Thank you



by:

I didn't like that this is designed for the wire to just come out of the wall panel into the rear cargo area. I cut the wire, drilled a hole into the side pocket, inserted the wire through the hole and reconnected it. Now the wire stores neatly entirely in the side pocket.



by:

Quick install. Easily fit in fuse box. Though I pulled the wire out the side as seen in the pic rather than at the bottom of the door opening. There was an extra white connector but I didn't see anything to connect it too, so I disconnected it.



by:

Easy install with directions and video combined covering most steps. Harness had additional multi connector that was not used (but not mentioned in any directions). Glad I read earlier review that noted this before my install. Decided to store harness in vacuum hatch when not in use.



by:

Worked!! Quick install.



by:

Was a good price, shipped fast, and fit my car just like it was supposed to!



by:

Very easy to install. I did not like the idea of the wiring just hanging in the trunk area, so I cut an opening into the storage compartment on the side trim panel so I could feed the wiring into it and keep it there when not in use.

Roy profile picture

Roy

5/15/2013

Great idea - I did the same thing, thanks! Installation was very easy, under 30 minutes start to finish.

Patrick B. profile picture

Patrick B.

5/15/2013

Glad to hear the install went well for you. Enjoy the new towing setup!
John O. profile picture

John O.

7/13/2013

did the same thing. worked well. Thanks for the idea.



by:

E trailer is a very great company, excellent follow thru and attention to detail. Their videos make installion a breeze. Even if you mess up and buy a stupid piece of crap Chinese company. Go with USA made and produced product. Might be a few dollars more, but very worth it. Buy Etrailer products only,or you will regret it.



by:

Super easy to install, haven't hooked a trailer to it yet, but honestly less than 5 minute project! Couldn't ask for better, and saved a lot by doing it myself!!



by:

Worked out perfect for my 2012 Odyssey. Easy to install, just watch the video.



by:

It worked great and was relatively easy to install.



by:

Easy to install. the etrailer video really helped. install took less than 30 min. bought a cheap tester and everything worked fine.



by:

Easy installation, took approx 25 minutes or so. Pulled back trim and plugged in... EASY. Came with everything I needed including fuses, twist ties, and adhesive for unit.

Must difficult part was making sure I could find the right fuse locations in the car to add.

Bought with receiver kit. Whole installation took approximately 45 minutes (a little longer to make sure wiring was put in place).

2 days later used it unexpectedly to retrieve friend's broken down vehicle... worked great!

Bob I. profile picture

Bob I.

7/22/2020

Sill working out great! Durable, no problems using, it has more than paid for itself.



by:

orderihng process was seamless and quick, with total cost in line with competitors. All in all a smooth event. NOW hoping the YouTube videos are a reliable indicator of the time it will take to change the broken one for the new one. Removing interior panels is always a bit of a pain....


25
25

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

  • Will The Curt T-Connector C56378 Work On A 2015 Honda Odyssey With Backup Sensors?
    Hey Robert, thanks for reaching out. The Curt T-Connector Vehicle Wiring Harness # C56378 will work on the 2015 Honda Odyssey with backup sensors. That video you saw is an older video and at the time it was made, the harness did not have compatibility with the backup sensor. Curt has since added an additional connection to the harness that allows it to work with the backup camera/sensor. So you will be just fine to use it on your Odyssey. So get that harness, plus the Curt # C13068 hitch...
    view full answer...
  • Recommended 7-Way Connector for a 2015 Honda Odyssey
    The wiring for your trailer's marker lights on the 7-way connector are on different circuits than the Curt item # C56378 controls. You'll need a 7-way connector on your 2015 Honda Odyssey to control the running lights. You can add one with the Universal Installation Kit for Trailer Brake Controller item # ETBC7. The kit includes a pre-wired 7- and 4-way trailer connector that mounts easily at the rear of your vehicle with an included bracket. This kit is designed for use on a vehicle...
    view full answer...
  • Troubleshooting Trailer Wiring Harness for 2015 Honda Odyssey Not Working
    Hey Ray, so you did a good job troubleshooting your trailer wiring harness and it is bad unfortunately. You would need to replace the entire kit with a new one like with the Curt # C56378. This happening is pretty common and it's actually a designed feature. In the event your trailer has a short in the trailer wiring the converter box will basically "sacrifice" itself to prevent the short from getting to your vehicle wiring which can easily be damaged. What kind of trailer are you towing?
    view full answer...
  • Parts Needed to Add 7-Way to 2017 Honda Odyssey
    Hey Ben! We do have a 7-way that will fit your 2017 Honda Odyssey. You will still need to pick up a 4-way, I recommend the Curt # C56378. Then you can upgrade it to a 7-way using the Universal Installation Kit for Trailer Brake Controller # ETBC7. This comes with the adapter, wiring, breakers, and everything else you need to add a 7-way to your vehicle. Are you towing a camper with brakes? Assuming you are, you will also need a brake controller. I recommend the Redarc Tow-Pro Liberty #...
    view full answer...
  • How to Install a 7-Way Connector on a 2014 Honda Odyssey
    Hey Casey! I've attached the instructions below along with a couple of installation videos for both the Universal Installation Kit item # ETBC7L and the item # ETBC7. The difference between the two 7-Way wiring harnesses is a blue wire that carries the brake controller signal. This is an important difference so I wanted to point out it's significance. The item # ETBC7L does not have a blue brake controller wire and can only be used with a wireless brake controller like the Curt Echo item...
    view full answer...
  • Why Would There Be Check Engine Light After Install of Trailer Wiring 2011 Honda Odyssey
    Hey Lucas, that's no good! Did you check and make sure all of the fuses were installed in the correct location? I would check that and then if that persists try removing the kit entirely to see if the problems go away to make sure the problem is the harness. Sometimes issues like this are simply that the connectors aren't seating properly and removing and reinstalling the kit takes care of everything so you might also try that.
    view full answer...
  • What is the Extra Connection With White Wire on Curt 4-Way Harness for 2014 Honda Odyssey Touring
    The Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C56378 has the second white quick connect and wire to give you the backup camera function. It is a through wire to allow that system to function correctly. If you have the backup camera, there will be a connection next to the other 4 wire connection point for you to plug it into.
    view full answer...
  • Troubleshooting Curt Trailer Wiring Harness on 2012 Honda Odyssey
    The Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C56161 is not a fit for your 2012 Honda Odyssey. It is only a confirmed fit for 2005 to 2010 models. For your 2012 model, you would need # C56378 which replaced the C56118. If that is the model you have, then I recommend checking the connections behind the driver's side trim panel in the rear cargo area of your Odyssey. Check the pins to ensure there are no bent pins and then make sure the ground connection...
    view full answer...
  • Recommended 7-Way Wiring Harness for a 2016 Honda Odyssey
    To add a 7-Way connector to your 2016 Honda Odyssey you will need to add two different wiring harnesses. The first harness you will need is the Curt T-Connector Vehicle Wiring Harness item # C56378. This harness is custom fit and plugs into existing wiring behind the driver's-side interior trim panel in your rear cargo area. The second harness you will need is the Universal Installation Kit for Trailer Brake Controller item # ETBC7. The kit includes a pre-wired 7- and 4-way trailer connector...
    view full answer...
  • What Wiring Harness and Brake Controller do You Recommend for My 2014 Honda Odyssey?
    For wiring to add a brake controller to your tear trailer when towing with your 2014 Honda Odyssey, the vehicle must first have a 4-way wiring harness. If you need a 4-way, I recommend the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118521. This harness comes with a better converter box than the Curt # C56378 or the Hopkins # HM11143114. Once the 4-way is installed, you are ready for the 7-way. For that harness, I recommend the Universal Installation Kit for Trailer...
    view full answer...
  • Curt Trailer Wiring Harness Does Not have Power on a 2016 Honda Odyssey
    There are a couple of things to check with the installation of Curt trailer wiring harness # C56378 on your 2016 Honda Odyssey. First, make sure the fuse is installed in the red power wire. If it is installed make sure that the fuse is good and replace if needed. Also make sure that the white ground wire is attached to a bare metal surface. Next check that the second fuse is installed in the proper location and that it is not blown and move/replace if needed. According to the instructions:...
    view full answer...
  • Parts Needed For Installing a Trailer Brake Controller On a 2016 Honda Odyssey LX
    The Curt Venturer NEXT Trailer Brake Controller # C74VV is a time delayed brake controller which will output the same braking force no matter how hard you brake in your 2016 Honda Odyssey LX. The Curt TriFlex Trailer Brake Controller # C24VV is a step up from the Venturer as it is a proportional controller. This controller has a sensor built in to sense braking inside your Odyssey and adjust the trailer brakes to match. This makes it a much easier controller to use. Both these controller...
    view full answer...
  • Is Curt T-Connector Vehicle Wiring Harness Compatible With 2015 Honda Odyssey With Backup Camera
    The Curt T-Connector Vehicle Wiring Harness # C56378 did not have compatibility with a backup camera when the video was made. You can see in that video that it lacks the additional connection with the white wire that it now comes with. This was added later, and will allow you to plug the wiring harness into both connection points on the panel which will allow you to use the backup camera. That being said, I would recommend the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector...
    view full answer...
  • Troubleshooting Wiring on 2013 Honda Odyssey
    If you used a circuit tester such as # PTW2993 to check the signals going into the converter box of wiring harness # C56378 and there is no voltage, quickly double check to ensure that the plug-in connectors are secure. Try unplugging them and then plugging them back in. Also take a look at the wires themselves to make certain they aren't crimped, broken or damaged in any real way. In very rare cases, the converter box could be bad, and you would need to replace the unit.
    view full answer...
  • Trailer Running Lights Not Working When Connected to 2012 Honda Odyssey with Curt Wiring Harness
    The first and easiest thing to check is the ground connection for Curt wiring harness # C56378. A weak ground could be causing the problem. The ground should be attached to a clean and corrosion free bare metal surface on your 2012 Honda Odyssey. You may need to sand away any paint or coating to get to bare metal. If that does not solve the problem then there are a few other things you can check. I have included a link to our help article on troubleshooting 4/5-Way connectors. This is...
    view full answer...
  • Recommended Hitch for a 2015 Honda Odyssey w/ a Vantage Mobility Northstar Package
    Hey Jimmy! It looks like the Vantage Mobility Northstar Packages don't alter the rear end of the 2015 Honda Odysseys. You will want to confirm this because all of our available hitches are set up for unaltered factory set ups. If this is the case, I recommend our etrailer Hitch item # e98862. This hitch is custom fit and bolts to your Honda with included hardware. It is a class III hitch with a 2" receiver, that has a 3,500 lbs towing capacity, and a 350 lbs maximum tongue weight. I...
    view full answer...
  • Trailer LED Tail Lights Light Up Dim When Connected to Vehicle with Curt Trailer Wiring Harness
    Curt trailer wiring harnesses like # C56378 sometimes have the exact issue that you are describing. The issue is that there is some bleed over power from the powered converter that can light up LED lights ever so slightly. This is usually not an issue because at night you would have the running lights on any way and during the day it should not be all that visible. The reason that it happens with LED lights and not incandescent lights is that the LED lights draw much less power to light...
    view full answer...
  • Recommended Trailer Wiring Harness For 2016 Honda Odyssey Without Factory Tow Package
    We have just what you need! For your 2016 Odyssey I recommend the Tekonsha T-One # 118521. This will give you a 4-flat connector which should be all you need for your boat trailer. Install will be quick and easy, just plug in behind the driver side trim panel, connect your ground and install the included fuses. I prefer these Tekonsha brand harnesses over other brands. Tekonsha is known to be the best as far as quality and dependability.
    view full answer...
  • Hitches and Recommendations for Towing a Pontoon Boat and 5 Bikes on a 2016 Honda Odyssey
    The best hitch you can equip your 2016 Honda Odyssey with is the Draw-Tite Max-Frame, part # 75270. I've linked to a video installation of this hitch on a 2016 Odyssey. It's a Class III hitch with a 2" receiver that has a maximum gross tongue weight of 675 pounds and a maximum gross trailer weight of 4500 pounds. With a weight distribution system added, that maximum trailer weight goes up to 5000 pounds, which leads me to your next question. The maximum towing capacity is a reference to...
    view full answer...
  • Recommended Hitch, Wiring Harness, and Mounting Brackets for a 2017 Honda Odyssey
    To mount the Curt T-Connector Vehicle Wiring Harness item # C56378 to the Draw-Tite item # 76025 you will want to use the No-Drill Mount Bracket item # 18136 and the item # 18144. This will allow you to install the 4-way farther down from the hitch receiver without drilling. There's a lot going on there with the ball mount and safety chains. My personal preference is to get the wiring out of the way. The Curt Easy Mount Bracket item # C58001 you were looking at will work though. Both...
    view full answer...
  • Troubleshooting Trailer Turn Signals On a 2015 Honda Odyssey That Aren't Working
    The Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # C56378 needs to have 3.0 amps per side, so it looks like your turn signals are not pulling enough power. To test your 4-pole connector, I recommend using the Brophy Circuit Tester for 4-Pole Flat Trailer Connector # F4CT. This will plug into your existing 4-pole and quickly and easily check the conductivity of all the circuits. You can also reference the FAQ I've attached to this answer page to dive a bit deeper.
    view full answer...
  • Transferring a Trailer Hitch From a 2008 Honda Odyssey to a 2012 Honda Odysssey.
    Both Draw-Tite Trailer Hitches, part # 75270 and # 36417, are compatible with the 2012 Honda Odyssey. I recommend checking the bolts and bolt holes for wear prior to transferring to the 2012, and ensuring that there isn't any damage, cracks or severe rust on the hitch. For a wiring harness, I recommend Curt's T-Connector, part # C56378. This installs into the existing wiring in your taillights to quickly add a 4-pole connector. I've included a video of the Tow Ready kit, part # 118521...
    view full answer...
  • Trailer Wiring For A 2016 Honda Odyssey
    To get your 2016 Honda Odyssey set up correctly for pulling a trailer you first need to install the Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector Item # C56378. This harnes gives your trailer the proper lighting functions. Since your trailer has a seven pole connecter and you are wanting to charge your battery on your trailer while towing, you need a power wire from the vehicle battery to the plug. I recommend the 7-Way RV Upgrade Kit for Trailer Brake Controller...
    view full answer...
  • Trailer Hitch Recommendation for 2014 Honda Odyssey
    All of the hitches for your 2014 Honda Odyssey will require some minor rear fascia trimming to install. My favorite hitch to recommend though is the Draw Tite part # 76025 as it only has the hitch tube that hangs below the rear bumper. This makes it quite a bit less visible than the other available hitches. The install is pretty basic for a mechanic which means that any local mechanic to you would have no problem installing it. I attached an install video for you to check out as well. For...
    view full answer...


< Previous
12




Info for this part was:

Employee Lindsey S
Edited by:
Lindsey S
Employee Jameson C
Expert Research:
Jameson C
Employee Jacob T
Video Edited:
Jacob T
Employee Dustin K
Video Edited:
Dustin K
Employee Chris R
Video Edited:
Chris R
Employee Jonathan Y
Video Edited:
Jonathan Y
Employee Cole B
Installed by:
Cole B
Employee Wilson B
Updated by:
Wilson B
Employee Kristina F
Updated by:
Kristina F
Employee Isabelle B
Updated by:
Isabelle B
Employee Amanda M
Written by:
Amanda M
Employee Robert C
Test Fit:
Robert C
Employee David F
Test Fit:
David F
Employee Jacob H
Test Fit:
Jacob H
Employee John A
Test Fit:
John A
Employee Thomas T
Video by:
Thomas T
Employee Ethan H
Video by:
Ethan H

At etrailer we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time.


Product Experts Available Now!
Call 1-800-940-8924