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Hopkins Plug-In Simple Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

Hopkins Plug-In Simple Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

Item # HM43354
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Custom Fit Vehicle Wiring

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Hopkins Plug-In Simple Vehicle Wiring Harness with 4-Pole Flat Trailer Connector 4 Flat HM43354
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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. 1-800-496-5010 to order Hopkins custom fit vehicle wiring part number HM43354 or order online at Free expert support on all Hopkins products. Guaranteed Lowest Price and Fastest Shipping for Hopkins Plug-In Simple Vehicle Wiring Harness with 4-Pole Flat Trailer Connector. Custom Fit Vehicle Wiring reviews from real customers.
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  • Reviews (10)
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Hopkins Custom Fit Vehicle Wiring - HM43354

  • Custom Fit
  • Trailer Hitch Wiring
  • 4 Flat
  • Powered Converter
  • Hopkins

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.


  • 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 behind tail lights
    • Plug in connector - no cutting or splicing
    • 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
  • Protective connection terminals resist corrosion
  • Comes with dust cap for 4-way flat connector, cable ties, and terminal grease packet for electrical connections
  • 90-Day limited 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 tail lights. You will have to remove the tail light assemblies to access this harness. Once you've plugged in the connector, run the red hot lead up to your car battery. Connect the included fuse holder, and then connect the fuse holder to the positive terminal on your battery.

T-One Connection Location Points Behind Tail Lights

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

Powered Tail Light Converter

A tail light converter is built into this T-connector. This converter is a 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.

43354 Plug-in Simple Hopkins T-Connector with 4-Pole Trailer Connector

This Product Fits The Following Vehicles

California residents: click here

Video of Hopkins Plug-In Simple Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for Review of Hopkins Custom Fit Vehicle Wiring - Trailer Hitch Wiring - HM43354

Ellen: Hey, everyone. I'm Ellen at, and today we're going to be taking a look at the Hopkins plug in simple wiring harness with four-pole flat trailer connector.This is going to give you all the wiring functions that you typically will need for towing a trailer or using any kind of accessory that has this flat, four-pole wiring connection. This is going to give us a working connection for our running lights, our turn and stop lights, and it also has our ground port there, so that's where we get the four. It's from ground, stop, turn, and running lights.So we're have our wiring come out, goes into this little bundle, and then it goes into our converter box. This takes the signals from our vehicle and converts that into a usable signal for our four-pole. It has custom fit ends that are going to go right into your vehicle's harness, so you don't have to worry about any kind of cutting or splicing into your vehicle's wiring.

It all just plugs up with these custom fit connectors. Now, this wiring in particular is going to be a custom fit for the Toyota Tacoma for the 2016 through the 2019.So these two will be for our power and running light circuits. The green wire will be for our passenger side turn signals, and then the yellow wire will be for our driver's side turn signals. We'll also have this red wire here. This is going to be for our standalone power so we don't have to worry about drawing on our vehicle's electrical system.

It has its own power source, so you don't have to worry about this dimming the lights in your vehicle or anything like that. It just connects directly to the battery.So we have this bulk of wire that gets connected into this little red wire here. The other end is going to go all the way up to your engine bay and connect to your battery. Of course, you'll want to put your fuse holder in between there so we protect our vehicle's wiring and also our connection here.It comes with a 15-amp fuse. Whenever you install this, you will want to take out that fuse before you actually make the connection.

But one nice little thing that Hopkins does is they actually pre-crimp some of these connectors on there so you only have one crimp to make here, and then another one at the other end.Now this one is actually a heat shrink butt connector, which is nice because it's going to keep out any water, dirt, or debris from getting into that connection and causing issues. Typically you use those whenever the connection is being made on the outside of the vehicle. In the engine bay, you typically won't have too much trouble, but things can get in there, so it's a good idea to have that on there. This connection will be most likely made inside your truck, so you don't have to worry about this being exposed to any water or debris.Whenever you run this bulk wire, you'll probably want to run it outside of the vehicle, so if you can find a nice grommet to pop out, maybe make a little slit through, and then run that wiring down, that's always a good option. If you do go with that grommet option, it's always advised to seal that up with some silicone sealant to make sure that you don't get any gas fumes or any water coming into the cab of your vehicle.

You can find silicone here at as well, sold separately.Another nice little addition that Hopkins includes is some terminal grease. This helps to keep our connections free of any corrosion from any water getting in there. So put it in all your connections going into your factory wiring, and all of these, and also on your four-pole. This is really the more important one. This is probably going to be hanging outside your vehicle most of the time.Whenever you install this, you can, again, run the four-pole outside your vehicle through maybe the same grommet that you're running your power through, or you can typically, if you're using this with a vehicle that has a hatch, you would run this outside there, but on your truck you probably won't have that option. So this is going to be living outside the vehicle.It does come with a dust cap to go on there, has a little bump out where you can make sure that this sits down on the connector, and then that keeps all those terminals closed. But still not a bad idea to have some terminal grease to keep those connections working for a long time. It just helps to prevent any kind of rusting or corrosion so they last for many years.So the install really isn't too bad. You just have to make those connections at all those points I mentioned earlier. Pretty much comes with everything you need.The last connection you'll make is the ground connection, or this last one, to go over, and it does come with a self-tapping screw to make that connection. You want to put this into a nice chassis ground somewhere that has bare metal that will connect and make that ground connection. If you can find a factory stud, that's always advised too since that way you're not having to put another hole into your truck. So you got some options there.But pretty much comes with everything you need. Little pile of small zip ties as well. And as far as the specs with this, this has a amp rating of three amps per circuit for the stop and turn lights, and six amps per circuit for the taillights. It does come with a 90-day limited warranty from Hopkins, and overall will give you that connections that you need to get all your wiring functions and stay within compliance while you're towing your trailer or using any other accessory.That's going to do it for our look at the Hopkins plug in simple vehicle wiring harness with four-pole flat trailer connector.

Customer Reviews

Hopkins Plug-In Simple Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - HM43354

Average Customer Rating:  4.9 out of 5 stars   (10 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.


Wiring harness works great no issues, but so far anything I have bought from etrailer has meet or exceed my expectations.

2021 Toyota Tacoma

This wiring harness is a life saver . Didn't know how I was going to get the lights to work on my trailer for my 2021 Tacoma. Then I found this harness on line. It's a perfect fix. Thanks


Looks easy what can be time consuming! About 40 minutes to install!


The best company I have delt with by far.the most awsome customer service i have ever had(thank you Carol C)








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

  • How To Run 12v Battery Wire for Hopkins HM43354 on 2020 Toyota Tacoma
    The best way to run the wire for the 12v power supply from the Hopkins Plug-In Simple # HM43354 to the battery on your 2020 Toyota Tacoma is going to be under the vehicle, while keeping it away from moving parts and parts that could heat up. I've linked one of our helpful articles on routing the 12v power wire to the battery that I recommend having a look at.
    view full answer...
  • Will the Hopkins Trailer Wiring Harness for a 2016 Toyota Tacoma Fit Models Without Tow Package
    The Hopkins Plug-In Simple Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part # HM43354 is a confirmed fit for a 2016 Toyota Tacoma without tow package. It plugs in behind the tail lights which would be isolated from any tow package wiring.
    view full answer...
  • Why Does 4-Way Wiring Harness Have Hot Lead on 2017 Toyota Tacoma
    Each of the 4-way wiring harnesses for your 2017 Toyota Tacoma do require a hot lead run to the battery, and the reason for this is to power the module. This is needed in your Tacoma and other vehicles in order to protect the tail light circuits from being overloaded, as they are not able to provide enough power without being damaged. You are correct that there are plenty of other vehicles that this isn't needed, though through testing, the harness manufacturers have determined the hot...
    view full answer...
  • What Hitch and 4-Way Wiring Harness do You Recommend for My 2022 Toyota Tacoma?
    For a great hitch harness for your 2022 Toyota Tacoma, I recommend the Curt Hitch - 2" # C13264. In addition to the 900 pound maximum tongue weight capacity and the 8,000 pound gross towing capacity, the Curt hitch comes with a gloss outer coating over the base coat that gives you superior rust and corrosion resistance than the other hitches we carry. Also, the hitch is manufactured here in the U.S.A. Another great thing about this hitch is that it installs only about 4 inches from the...
    view full answer...
  • Installing 4-Pole/7-Way Trailer Connector on 2020 Toyota Tacoma
    We don't offer a 7-way trailer connector that would plug into the connector you mention, but we do have an option that would provide you with a 7-way and a connector for a brake controller. I'd recommend the Tekonsha # 22117 which would plug inline at the connection between the vehicle's taillight wiring harnesses and the taillight assemblies. As outlined in the linked installation instructions, you'll run the body harness to the front to connect at the battery power and ground, with a...
    view full answer...

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Info for this part was:

Employee Mike L
Expert Research:
Mike L
Employee Lindsey S
Edited by:
Lindsey S
Employee Kathleen M
Installed by:
Kathleen M
Employee Alexander C
Written by:
Alexander C

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