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  1. Custom Fit Vehicle Wiring
  2. Hopkins
  3. Custom Fit
  4. Trailer Hitch Wiring
  5. 4 Flat
  6. No Converter
Hopkins Plug-In Simple Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector

Hopkins Plug-In Simple Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector

Item # HM40155
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Custom Fit Vehicle Wiring

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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 OEM tow package wiring harness - no cutting or splicing required. 1-833-496-1390 to order Hopkins custom fit vehicle wiring part number HM40155 or order online at Free expert support on all Hopkins products. Guaranteed Lowest Price and Fastest Shipping for Hopkins Plug-In Simple Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector. Custom Fit Vehicle Wiring reviews from real customers.
  • All Info
  • Reviews (7)
  • Q & A (0)
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  • Why etrailer?

Hopkins Custom Fit Vehicle Wiring - HM40155

  • Custom Fit
  • Trailer Hitch Wiring
  • 4 Flat
  • No Converter
  • Hopkins

Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. T-connector plugs directly into OEM tow package wiring harness - no cutting or splicing required.


  • Provides a 4-way flat trailer connector at the back of your vehicle to power your trailer's signal lights
    • Designed for use with a factory tow package
    • Compatible with 5-pole, 6-pole and 7-pole adapters (sold separately)
  • Connects quickly and easily - no cutting or splicing
    • Locate connection point behind rear bumper
    • Plug in connector
  • 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 factory tow package wiring harness, which is located behind the rear bumper, near the center of your vehicle.

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.

11140155 Plug-in Simple Hopkins T-Connector with 4-Pole Trailer Connector

Replaces 40155

Installation Details HM40155 Installation instructions

This Product Fits The Following Vehicles

California residents: click here

Customer Reviews

Hopkins Plug-In Simple Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector - HM40155

Average Customer Rating:  5.0 out of 5 stars   (7 Customer Reviews)

Quickly and easily install a 4-way trailer connector on your vehicle with this custom harness. T-connector plugs directly into OEM tow package wiring harness - no cutting or splicing required.


Product as described. Plug and play. Doesn't get any easier than this. I only trust etrailer for my plug, hitch and truck needs. And so should you.

1999 Ford F-250 and F-350 Super Duty

This plugged right into the truck wiring harness and was ready to go. As I understand it, there are two types of plug ins into your factory harness. Mine was more round rectangular rather than just round. Make sure you order the right one. It plugs right in behind the bumper on the driver's side of the spare tire. It was easy and worked great.

2001 Ford F-250 and F-350 Super Duty

Perfect replacement for stock wiring connectors


Had a great experience

2000 Ford F-250 and F-350 Super Duty

Great service and product worked perfectly. I will do more business with these folks and recommend them to my friends.

1999 GMC Sierra

Excellent I have been trying for a very long time to get this fix an the only place I have found with my part. Thanks awesome service


Exactly what i needed


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

  • 7-Way Trailer Wiring Kit for 2015 Honda Pilot
    The 7-way wiring harness you can use in your 2015 Honda Pilot is the Tekonsha kit # 118265. This is a custom-fit item made specifically for your Pilot with factory tow package. This kit includes the 7-way socket, harness, converter box, and relays. Please refer to the linked review video for more information on this kit.
    view full answer...
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  • Recommended 4-Pole Trailer Connector for 1999 Ford F350
    The Curt # C56032 isn't a fit for the 1999 Ford F350, but we do offer an option that will work. If you have the rectangular tow package connector on the driver's side frame rail behind the rear tire, you'll want to use the Hopkins # HM40155. If you have the round connector, use part # HM40975 which provides both a 7-way and a 4 pole.
    view full answer...
  • Available OEM Trailer Wiring Harness Kits for 1999 Ford F-250
    Hopkins Plug-In Simple Wiring Harness # HM40155 has a 4-pole flat trailer connector and is intended as a replacement for a factory 4-pole on your 1999 Ford F-250. We do have other wiring kits for your truck depending on how it was equipped from the factory; all kits are shown on the linked page. For example, parts # 118243 and # C55243 are 7-way kits that include fuses and relays to activate the additional circuits for the trailer.
    view full answer...
  • Trailer Wiring Harness Needed for a 2005 Honda Element
    I do have a solution that will work for your 2005 Honda Element but unfortunately neither the Hopkins # 43105 or their # HM40155 are confirmed fits for your vehicle. Instead you will need to use a universal option like the Tekonsha Wiring Harness Kit # 119147KIT. This comes with quick splice connectors that allow you to tap into the light functions on your Element. It also includes the wiring needed to run to your battery so that your trailer lights aren't pulling from your vehicle lighting...
    view full answer...
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  • Recommended Trailer Tow Harness For 2014 Honda Pilot
    We have a solution to your question. However, this particular tow harness, part # HM40155, fits 1999-2001 Ford Super Duty Trucks and does not fit your 2014 Honda Pilot. I recommend the Curt Wiring Harness, part # C56170, as the best fit for your needs. The Curt harness is built with surface-mount technology (SMT) that makes it smaller than "traditional" circuit boards. SMT eliminates the need for leads and performs well under rough road conditions and/or excessive vibration. Several...
    view full answer...
  • How To Hook Up Lights On a Flat-Bed Without Splicing
    In order to achieve your goal of not splicing into the factory trailer wiring harness we are basically going to create a wiring harness for the flatbed which would plug into the factory trailer connector. In order to do this we are first going to want a junction box, part # 3430001-JBK. Once we have the junction box we can then run the wires from the headache rack and tail lights to this with part # 16-4B-1 (per foot). After this is completed the only other thing we need to do is attach...
    view full answer...

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Info for this part was:

Employee Lindsey S
Edited by:
Lindsey S
Employee Jeff D
Installed by:
Jeff D
Employee Adam R
Expert Research:
Adam R
Employee Wilson B
Updated by:
Wilson B
Employee Alexander C
Written by:
Alexander C

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