1. Wiring
  2. Hopkins
  3. Trailer Connectors
  4. Trailer End Connector
  5. 4 Flat
  6. Plug and Lead
Hopkins Wiring Harness with 4-Pole Flat Trailer Connector - Trailer End - 4' Long

Hopkins Wiring Harness with 4-Pole Flat Trailer Connector - Trailer End - 4' Long

Item # HM38138
lowest price pledge
Our Price: $4.33
Wiring
Orders above $99 qualify for Free Shipping
Shipping Weight: 0.18 lbs
Quantity: 
In Stock, Ships Today
zoom in icon
zoom out icon
Comment field cannot be left empty.
Name field cannot be left empty.

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

Videos

Wire your trailer with this universal, splice-in wiring harness so that you can connect the trailer's wiring to your vehicle's during towing. Corrosion-resistant terminals are long-lasting. Meets SAE standards. Lowest Prices for the best wiring from Hopkins. Hopkins Wiring Harness with 4-Pole Flat Trailer Connector - Trailer End - 4' Long part number HM38138 can be ordered online at etrailer.com or call 800-298-8924 for expert service.
  • All Info
  • Reviews (21)
  • Q & A (17)
  • Videos (1)
  • Photos
  • Why etrailer?

Hopkins Wiring - HM38138

  • Trailer Connectors
  • Trailer End Connector
  • 4 Flat
  • Plug and Lead
  • Hopkins
  • 0 - 5 Feet Long

Wire your trailer with this universal, splice-in wiring harness so that you can connect the trailer's wiring to your vehicle's during towing. Corrosion-resistant terminals are long-lasting. Meets SAE standards.


Features:

  • 4-Way flat trailer-end connector plugs into the 4-way flat on your vehicle
  • Simple installation
    • Hardwire to existing trailer wiring
  • Corrosion-resistant terminals are long-lasting
  • SAE compliant


Specs:

  • Harness length: 4'
  • Wiring configuration:
    • White: ground wire
    • Yellow: left turn/brake light
    • Green: right turn/brake light
    • Brown: tail lights
  • 90-Day limited warranty


38138 Hopkins 4-Way Flat Connector - Trailer End - 48"

Installation Details HM38138 Installation instructions


California residents: click here


Video of Hopkins Wiring Harness with 4-Pole Flat Trailer Connector - Trailer End - 4' Long

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




Video Transcript for Hopkins Wiring - Trailer Connectors - HM38138 Review

Today we're going to be taking a look at the Hopkins wiring harness with a 4-pole flat trailer end connector. The 4-way flat trailer end connector is going to plug into the connector from your vehicle to power your trailer's signal lights. Pretty simple installation. It's designed to just hard wire to the existing trailer wiring. On the connector portion right here, it's going to feature corrosion-resistant terminals, so these are very long-lasting, and it's got a nice easy-grip design, which allows for simple plugin and disconnect. The overall length of our harness is going to measure about 4 feet long. When it comes to the wiring configuration, you're white wire's going to be your ground.

Your yellow wire's going to be for your left turn brake. Green is for right turning brake, and brown is for your taillights. That's going to do it for today's look at the Hopkins wiring harness with a 4-pole flat trailer end connector.


Customer Reviews

Hopkins Wiring Harness with 4-Pole Flat Trailer Connector - Trailer End - 4' Long - HM38138

Average Customer Rating:  4.9 out of 5 stars   (21 Customer Reviews)

Wire your trailer with this universal, splice-in wiring harness so that you can connect the trailer's wiring to your vehicle's during towing. Corrosion-resistant terminals are long-lasting. Meets SAE standards.

- HM38138
by:

Great product for the money I had replace my trailer wire at the trailer connector end , the wires are even labeled . 436791



- HM38138
by:

Simple item, but high quality, good value, and fast shipping. 711330



- HM38138
by:

Very pleased. Exactly what I wanted a a very fair price. Shipping was fast. I would definitely order from them again and probably will. 691761



- HM38138
by:

Parts as described, spare tire and rim for my utility trailer, fast shipping, able to order exactly what I needed, recommend! 682944



- HM38138
by:

The product was as advertised...good quality at a very reasonable cost. Delivered expediously. Thanks , Mark 677256



- HM38138
by:

Very easy to find online very fast shipping wonderful to deal with. 660992



- HM38138
by:

Good quality. Fast shipping. 654246



- HM38138
by:

AAA+ 649338



- HM38138
by:

Nice quality wire and connector that is still working well after a good summer worth of use 646622



- HM38138
by:

The Hopkins Wiring Harness was exactly what I needed to repair the trailer. Very affordable. 479641



- HM38138
by:

As described, no problems, good quality. 445256



- HM38138
by:

Does the job. Good company. 441156



- HM38138
by:

I've only had the products for a couple of days so I can't vouch on quality. Looks good. Doing business with etrailer was a good experience. 428905



- HM38138
by:

real good quality, 394894


Comments
Thanks for the review on the Hopkins Trailer Connector, Jim!! Hopkins appreciates your business.
Hopkins C from - 06/21/2017

25260

- HM38138
by:

easy to find anything i need , great price and service. no need to go anywhere else,fast delivery. 386821


Comments
Thanks Pa John for the great review and rating!! Hopkins appreciates your business.
Hopkins C from - 05/31/2017

24366

- HM38138
by:

Product performs as expected, distributor stand behind products in accordance to need. 383209


Comments
Thanks Sam for reviewing the Wiring Harness!! Hopkins appreciates your business.
Hopkins C from - 05/23/2017

24079

- HM38138
by:

The wiring harness is cheap and easy. 375568


Comments
Thanks for the review on the Hopkins Wiring Harness, Nick! Hopkins appreciates your business.
Hopkins C from - 05/11/2017

23806

- HM38138
by:

Exactly what I wanted and expected. Received it quick 342663



- HM38138
by:

Excellent. Fit the factory installed tow vehicle connection perfectly. (F250) Easy to install and worked as it should. 336320



- HM38138
by:

Good quality and price 317653



- HM38138
by:

Fixing the trailer issue. 312900


21
21

Ask the Experts about this Hopkins Wiring

  • What Does Some Trailer Wiring Have 2 Brown Tail Light Wires
    Common 4-pole trailer wiring like # HM38138 uses one wire, the brown one, for the running lights on both sides of the trailer. Sometimes what is called a 'wishbone' harness is installed on the trailer and this simply uses two separate running light wires - brown with yellow for left and brown with green for right - to make it easier to connect to the trailer lights since that way no jumper wire will be needed to cross from one side to the other. Some examples of wishbone style 4-pole...
    view full answer...
  • 4-Way Trailer Wiring Recommendation that Uses all 16 Gauge Wires
    For a 4-way that has all 16 gauge wire you would want the Wesbar 4-Pole Flat Connector # W787264. The part # HM38138 uses 18 gauge for all wires but the white that uses 16 gauge.
    view full answer...
  • Recommended Plug to add Lights to Trailer Tailgate
    In order to add lights on your trailer's tailgate that will allow you to remove it, you can use 2 Wire Loop # 9651P. What you would want to do is cut it in half and use one side for your tailgate and one side for your trailer. I've added a link to a video review for you to take a look at as well.
    view full answer...
  • Troubleshooting Trailer Wiring After Installing Lights And Wiring
    There could be a couple of reasons why the lights are not working now. You said you replaced some lights and wiring. I recommend checking all of the connections to make sure everything is secure and wired properly. You can use a circuit tester like part # 40376 to make sure all of the lights and wires are receiving current as designed. If everything checks out the problem is probably the ground connections. Check the inside of the trailer connector for corrosion. If you find any green...
    view full answer...
  • How to Re-Wire Trailer with 4-Pole Trailer Harness
    A 4-pole trailer wiring harness has three circuits plus a ground, the ground being carried on the white wire. You will just need to test the functions on each trailer wire to confirm how to connect them to a 4-pole pigtail like # HM38138. A junction box # 38656 and ring terminals like # 44-5310A will make it easier to get solid reliable connections. You will want to ground a battery negative terminal to the frame and apply 12V power from the positive terminal to each trailer circuit,...
    view full answer...
  • Determining Function of Non-Standard Wire Colors on Trailer to Install 4-Way Connector
    The best way to connect the 4-Way to your trailer wiring is going to be to test each of those wires by applying 12V power to them. By doing this you will be able to see what each wire activates on the trailer to verify their function. Going by wire color alone, as you are seeing, isn't always a good idea because trailer manufacturers or previous owners have a tendency to use non-standard wire colors. Once you determine their functions the trailer wire for left turn/brake light will...
    view full answer...
  • How To Hardwire A 4-Way Harness On A Small Utility Trailer
    In order to wire a 4-way harness onto your trailer, you will need a few simple items. The first of which will include our Deka Heat Shrink Butt Connector part # DW05744-10 and the Electrical Connector Dielectric Grease part # LT37534. The rest of the tools needed for this install should be fairly common in most toolboxes. Before you install the wires, you will need to strip back a 1/4" of the jacket from each wire and place them into opposite ends of the butt connector. After you have...
    view full answer...
  • Converting Euro 7-way To Standard 4-Way Flat Trailer Connection
    I am not familiar with the bike rack with lighting, however, you can rewire the 7 pin euro by function to the 4-way flat. I recommend using the Hopkins Wiring Harness with 4-Pole Flat Trailer Connector - Trailer End - 4' Long # HM38138 along with quick splices like # SWC501925-1 or butt connectors like # DW05744-5. The 4-way functions are: White=ground wire Yellow=left turn/brake light Green=right turn/brake light Brown=tail lights I've attached a photo of the Euro functions for you.
    view full answer...
  • Do 4-Way Connectors Have a Power Wire
    Trailer and vehicle 4-way connectors like you'll find with the 4-Way Flat Trailer Wiring Kit - Vehicle and Trailer Ends # HM48205 do not actually have a hot - or power - wire. As you can see by the cut out I added of the linked help article on trailer wiring (which I highly recommend checking out), a 4-way will activate running lights, brake lights and turn signals. I have added a link to our entire selection of trailer end 4-way connectors for you to take a look at.
    view full answer...
  • What Gauge Wire does 4-Way Trailer Wiring Use
    Typically 4-way wiring consists of 18 and 16 gauge wires. For a 4-way that has all 16 gauge wire you would want the Wesbar 4-Pole Flat Connector # W787264. The part # HM38138 uses 18 gauge for all wires but the white that uses 16 gauge.
    view full answer...
  • Does the Blue Ox Tail Light Wiring Kit with Block Diode # BX8811 Come With a 4-Way Connector
    The Blue Ox Tail Light Wiring Kit with Block Diode # BX8811 that you referenced does not come with a 4-Way connector as you stated. To add a 4-Way connector you can simply use the Hopkins Wiring Harness with 4-Pole Flat Trailer Connector # HM38138 and connect it to your current wiring using Butt Connectors # DW05744-5. For a look that is a little more clean and will provide you with a 7-Way to connect to your RV you can use the Hopkins Nite-Glow Tow Bar Extension Cord w/ Socket -...
    view full answer...
  • How to Connect Thinline LED Trailer Tail Light to 4 pole Connector
    To connect the Thinline LED Trailer Tail Light # STL59RB to your 2017 Kia Sportage's trailer wiring is fairly simple. It sounds like you are going to be mounting the light to a cargo carrier, or other hitch mounted accessory and would like to disconnect it easily when you're not using it. The Hopkins Wiring Harness with 4-Pole Flat Trailer Connector # HM38138 can be wired directly into the light and then plugged into your 4 pole connector. The 4 pole connector is the trailer side, so...
    view full answer...
  • Replacement 4-Way Option for Stainless Steel Trailer Hitch Receiver Step with LED Lights
    If you needed to wire in a new 4-way to the # CR-605LED you could easily use the # HM38138, but we don't have the exact same connector that would match to this step. For butt end connectors we have the part # 05731-5 that would give you 5.
    view full answer...
  • Troubleshooting Turn Signals Not Working on a 4-Pole Setup
    The first 2 things that you want to check when experiencing wiring problems is all of your grounds and the connectors on both your tow vehicle and trailer. You will want to make sure that the grounds are secure and have a metal-to-metal contact. Sometimes even some paint can cause lighting issues. To replace a damaged connector on your trailer you will need part # HM38138; for your tow vehicle you can use part # C58044. If all of that looks good then you will want to test the wiring...
    view full answer...
  • Adapter Recommendation for 6-Way on Trailer to 4-Way on Vehicle
    For a 6-way to way adapter we do have the part # 30637. With this your trailer's 6-way would plug into it and then the 4-way of the adapter would plug into the vehicle. Best solution will be to replace the 6-way on your trailer with a 4-way to match your vehicle as that will eliminate the need for an adapter. For that the part # HM38138 would be your best bet.
    view full answer...
  • Replacement 4-Pole Trailer-Side Connector
    To replace the damaged 4-pole connector on your Pilot Stainless Steel Trailer Hitch Receiver Step with LED Lights # CR-605LED you can use part # HM38138, or if you prefer a coiled cord part # 54000-026. You will connect the new 4-pole's wiring color for color and you can use butt connectors # DW05743-5.
    view full answer...
  • Parts Needed to Re-Wire European Trailer to RV-Style Trailer Wiring
    Thank you for the photo of your trailer's European wiring. You will be best served by replacing the Euro style connectors on your trailer to the RV-type. We do not offer Euro style wiring harness kits for vehicles. The part you referenced, adapter # 118710, adapts a European vehicle to a 4-pole type connector but does not adapt the trailer to match U.S. wiring. Euro wiring has every function on a separate wire; while here in the U.S. trailer wiring combines the stop and turn signals. The...
    view full answer...

Do you have a question about this Wiring?




  • Why etrailer.com?

    At etrailer.com we guarantee:
  • Highest quality wiring for the best price.

    Our Lowest Price Pledge ensures you will never overpay for the parts you need.
  • Real product know-how.

    We make sure that the products we sell are what we say they are, and that they work the way they are supposed to work. Get real advice from a real person who has the knowledge and expertise needed to solve your problem.
  • Most detailed, accurate wiring information available.

    Because we take providing accurate product information seriously, we take our own detailed product photos, demo videos and installation videos, as well as verify measurements, instructions, and vehicle fit information.
  • Installations, made easy.

    We love helping people and have the most highly-trained customer service, hands-on experience, step by step videos and installation instructions.
  • Fast shipping.

    Your order is automatically routed to get out of our warehouse and to your door as quickly as possible. Receive free shipping on orders over $99.
  • Personalized service for life.

    We provide one-on-one, personalized service from the ordering process through the life of your product.
  • Trusted since 1946.

    We've been serving customers since our parts store first opened in 1946 and continue to be recognized by our customers, our vendors and third parties for exceptional service.
  • Returns Policy

    Need to return an item? No problem. Please read our Returns Policy for more information.

Info for this part was:

Edited by:
Lindsey S
Expert Research:
Jameson C
Expert Research:
Adam R
Expert Research:
Jeffrey L
Installed by:
Cole B
Written by:
Alexander C

At etrailer.com 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. Let us know if anything is missing or if you have any questions.