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  5. 4 Flat
  6. Powered Converter
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 # HM11140525
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Custom Fit Vehicle Wiring

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Hopkins 4 Flat Custom Fit Vehicle Wiring - HM11140525
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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. Call 800-298-8924 to order Hopkins custom fit vehicle wiring part number HM11140525 or order online at etrailer.com. 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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Hopkins Custom Fit Vehicle Wiring - HM11140525

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

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 in rear cargo area
    • Plug in connector
    • 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 in your rear cargo area on the driver's side and passenger's side. You will have to remove some interior paneling 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.

Once installation is complete, the 4-way flat connector will be stowed in your rear cargo area.

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.

11140525 Plug-in Simple Hopkins T-Connector with 4-Pole Trailer Connector

Installation Details HM11140525 Installation instructions

This Product Fits The Following Vehicles

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 Hopkins Custom Fit Vehicle Wiring - Trailer Hitch Wiring - HM11140525 Review

Today we're going to take a look at the Hopkins Plug In Simple Vehicle Wiring Harness, with the 4-Way Flat Trailer connector. Now this is a custom-fit part. It is designed to fit the 2010 and newer Ford Mustangs. Now on a custom-fit part, I always like to recommend for you to go to our website, use our Fit Guide. Put in your year and model vehicle and it'll show you if this'll work for your application. Now this harness provides this 4-Way Flat Trailer connector at the back of your vehicle, to power your trailer's signal lights. It is compatible with five pole, six pole, and seven pole adapters, that we do sell separately on our website.

This whole kit will connect very quickly and easily. There's no cutting or splicing of wires. Basically, you just locate your connection points that are in the rear cargo area, behind the tail lights. Plug in these connectors, one on each side. Ground your white wire and run your power wire to your vehicle's battery. This will include this tail light converter, which is this black box, here.

This is to ensure that your vehicle's wiring'll match that of your trailer. It is a powered module, means it connects directly to the battery. That's to avoid overloading your vehicle's electrical system. On your connectors here, they have protective connection terminals to help resist corrosion. Comes with this nice dust cap for the 4-Way. You can just attach that to the 4-Way plug and you can actually leave that attached if you prefer.

Then when you're not plugged into your trailer, just take your cover, put it over the terminals, and that protects them from any damage or from the elements. Comes with everything shown here, on the table. Nice set of detailed instructions on how to install everything, but it's pretty simple to install. All you have to do is start at the rear of the vehicle, again behind the tail lights. You want to start on the driver's side. You'll take this connector that has the yellow wire in it.

You'll connect that behind the driver's side tail lights. Plug that into the harness in the tail lights. Then you'll take this other connector that has a length of green wire and that means it'll run over to your passenger side when you get over there, behind the tail lights. Same way, you'll plug this in behind it. Once those are all plugged in, your converter here, you do want to make sure to attach that to a good, flat surface. They do give you some extra cable ties that you can run through here to hold it down into place. Then you'll have your two wires remaining, a white and a red wire. The white wire, with the eyelet on it, that's for your ground. You want to connect that to a good, clean ground if there's one nearby. If there isn't, you can use this grounding screw to make your own. The power wire has the butt connector on it, the red wire. That would need to run to your vehicle's battery, up to the front of the vehicle. They do include this length of wire to do that. What you'll want to do is take one end of this length of wire, put it in the butt connector, and make your connection. Run this all the way up to the front. Once you get to the front, you don't want to connect this directly to the battery. You want to run it through this inline fuse holder. When you get there, you just take the side that has the butt connector, install that, and then your other side of your fuse holder will have this eyelet, that'll go onto the battery post. Once you get that all installed, take your included 20 amp fuse, pop it into the fuse holder, just like that. Put your cap on and you'd be all ready for your system to go. Now again, they have some extra cable ties to take up any slack in the wiring and then they give you a nice package of terminal grease or dielectric grease, and what you want to do with that is, anytime you make an electrical connection, like at these plugins, you want to put some grease on there, and same way on the 4-Way. Put some grease on that so when you plug into your trailer, that dielectric grease'll help prevent any corrosion at those electrical connections. That should do it for the review on the Hopkins Plugin Simple Vehicle Writing Harness with the 4-Way Flat Trailer Connector.


Ask the Experts about this Hopkins Custom Fit Vehicle Wiring

  • How Much Weight Can be Carried with a Cargo Carrier on a 2015 Ford Mustang
    Let me start by saying you're definitely asking all the right questions to make sure you can safely carry your gear on a cargo carrier and you're definitely right to question what you were told. Most of what you're asking are things that we often tell people and they're completely taken off guard and surprised. 1. Yes, tongue weight matters and it is the only capacity requirement you need to worry about. Tongue weight is the force pushing down on a hitch from the weight that's suspended...
    view full answer...

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Info for this part was:

Edited by:
Lindsey S
Installed by:
Jeff D
Written by:
Alexander C

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