bing tracking image
  1. Trailer Wiring
  2. Hopkins
  3. Wiring Adapters
  4. Single-Function Adapter
  5. 4 Flat
  6. Plug Only
Adapter 6-Pole to 4-Pole with Built-In LED Tester and Cover

Adapter 6-Pole to 4-Pole with Built-In LED Tester and Cover

Item # 37325
lowest price pledge
Our Price: $11.88
You Save: 43%
Trailer Wiring
Orders above $99 qualify for Free Shipping
Shipping Weight: 0.18 lbs
In Stock
37325 - 4 Flat Hopkins Trailer Wiring
zoom in icon
slider vertical 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


Need help with installation?
Locate installers near me
Converts from 6-pole round adapter on your vehicle down to 4-pole flat adapter. Also included, circuit tester and plug cover. Lowest Prices for the best trailer wiring from Hopkins. Adapter 6-Pole to 4-Pole with Built-In LED Tester and Cover part number 37325 can be ordered online at or call 1-636-306-4830 for expert service.
  • All Info
  • Reviews (11)
  • Q & A (0)
  • Photos
  • Why etrailer?

Hopkins Trailer Wiring - 37325

  • Wiring Adapters
  • Single-Function Adapter
  • 4 Flat
  • Plug Only
  • 6 Round
  • Hopkins

Converts from 6-pole round adapter on your vehicle down to 4-pole flat adapter. Also included, circuit tester and plug cover.


  • Converts from 6-pole round adapter on your vehicle down to 4-pole flat adapter
  • Includes tester and cover

If your truck has the connector on the left, and your trailer has the connector on the right, you will want this adapter.
30200 18004
Vehicle End Trailer End



47325 Adapter 6 Pole to 4 Pole with Built-In LED Tester and Cover

Similar to 37308 or PK12717

California residents: click here

Customer Reviews

Adapter 6-Pole to 4-Pole with Built-In LED Tester and Cover - 37325

Average Customer Rating:  4.8 out of 5 stars   (11 Customer Reviews)

Converts from 6-pole round adapter on your vehicle down to 4-pole flat adapter. Also included, circuit tester and plug cover.

- 37325

Good product. Easy to use. I use it to plug my magnetic lights on my tow car. Works good.

Lee B - 09/17/2018

- 37325

Connector addapter was delivered very quickly. This was exactly what I needed to connect a cargo trailer to a previously installed Pollack boat trailer connector on my truck. It worked great and I am very pleased.

- 37325

etrailer is the first place I go to when I need something for my towing needs,....they usually have what I'm looking for at the best price,... the service is very good, with plenty of info on solutions to problems, I'm sure I will be ordering more in the future,....Thanks

- 37325

Outstanding. Eliminates wondering if tow vehicle wiring is working.

- 37325

Worked great for what I needed it for(Harley Triglide)

- 37325

It's all you guys said it would be and it fits so I'm happy thank you very much and Jesus loves you and so do I God bless you thank you

- 37325

Great product, I particularly like the LED readout so you can test your wiring

- 37325

Works just as expected.

- 37325

Great service, fast shipping, no problems, highly reccommend

- 37325

Very happy with my purchase. Good qual ity.

- 37325

works as intended


Ask the Experts about this Hopkins Trailer Wiring

  • Both Turn Signals Blink On Trailer When Brake and Signals are Applied at the Same Time
    The first thing I would check is the trailer side and vehicle side connectors for any dirt or corrosion and clean it out. That could cause a short circuit situation. I would then move on to checking the grounds on the trailer. The main ground should be connected to a bare metal surface on the trailer frame. Most trailer tail lights ground through the mounting studs unless there is an obvious ground wire. In either case, you will want to make sure the grounds are attached to clean, corrosion...
    view full answer...
  • Troubleshooting Trailer Blinkers that Both Blink When Either Turn Signal is Applied
    It sounds like you have the blinker circuit of your 1998 F150 run to the running lights circuit on your trailer wiring so when the blinker is applied both of your running lights are flashing. Any time you see trailer lighting that illuminates dimly when the wrong circuit is applied is usually indicates that there is a weak ground on the trailer wiring circuit. How that all works is beyond me, but what you will want to do is return the trailer to the previous wiring configuration you had...
    view full answer...
  • How To Wire a Gooseneck Trailer from Scratch with Just Trailer Lights
    You should not need any extra fuses. Trucks like the Dodge Ram 2500 are built for towing and should have enough power on those circuits. First I would wire the lights to the trailer and worry about the 6-Way last. I would wire the lights with the standard color code. That way if you sell the trailer or have to work on the wiring in the future, it is done in the standard method. The white wire is ground and should be attached securely to the trailer frame. It is best to have direct contact...
    view full answer...
  • Why Does a 6-Way to 4-Way Adapter Only have 4 Contacts
    An adapter such as # 37325 or # PK12717 will only have the necessary pins required by the 4-Way end. These are the basic lighting functions; left/right turn signals, brake lights, and running lights. And the 4th is the ground (the turn signals and brake lights are combined on the same circuit for each side of the trailer). A trailer that uses a 4-Way flat connector does not have the other functions on a 6-Way. If the connector on your 2004 Jeep Grand Cherokee is factory then it is likely...
    view full answer...
  • Is There An Adapter To Connect Lights To A Round Trailer Connector On Cargo Light Kit, # 20174
    It will depend on what you have as a normal round trailer connection on your vehicle. There is a 4 Round, 6 Round and a 7-Way Round connector. If you have a round 7-Way Round connector on your tow vehicle and you are wanting to connect the 4-flat connector on the cargo carrier light kit, # 20174, to it, you can use the Hopkins Heavy-Duty Trailer Coiled Wire Adapter for 7-Way to 4-Wire Flat, # HM47065. If you have a 4 round plug on your vehicle you can use the Hopkins Adapter 4 Round...
    view full answer...
  • How to Make an Adapter to go From a 4-way Flat Vehicle to a Separate 6-Way Round Trailer
    So it sounds like your trailer has separate circuit tail light harness meaning the brake lights are separate from your turn signals and your motorhome has a combined circuit 4-way. I believe the easiest way to accomplish towing this setup would be to wire up a tail light converter like the Curt adapter # C56196 to separate your tow vehicles tail light signal. The method I will recommend for this will basically give you an adapter to allow your trailer to be towed by motorhome, but then...
    view full answer...
  • Trailer Wiring Adapter to Go From Vehicle 4-Way Flat to 6- or 7-Way Trailer Connector
    For a trailer that has a 6-Way and a vehicle that has a 4-Way flat you will need a different kind of adapter. Double check the pins on the trailer side. If the connector does have 6 round pins then for an adapter you will need # 30637. Your 4-Way will plug into the 4-Way on the adapter and the white wire will need to be attached to the vehicle frame. This will provide lighting functions. If you also want the brakes and 12 volt circuit to work then I recommend # ETBC6 which is the adapter...
    view full answer...
  • Installing Curt Easy Mount Trailer Connector Bracket, Part # C58000, on 2013 Toyota RAV4
    The Curt Easy Mount Bracket for 2-inch hitches, part # C58000, provides a mounting surface for both flat (4- or 5-way) and round (6- or 7-way) vehicle side trailer connectors. It is made of durable powder-coated steel and includes stainless steel hardware to secure it to a 2-inch hitch, such as the Curt # C13149. (This Class III hitch carries 525-lb tongue weight and 3500-lb gross towing weight ratings; 4000-lb GTW with weight distribution.) The one end of the Curt bracket mounts to the...
    view full answer...

Do you have a question about this Trailer Wiring?

  • Why

    At we guarantee:
  • Highest quality trailer 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 trailer 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:

Employee Michael H
Expert Research:
Michael H
Employee Jameson C
Expert Research:
Jameson C
Employee Adele M
Updated by:
Adele M
Employee Laura H
Updated by:
Laura H
Employee Wilson B
Updated by:
Wilson B
Employee Alexander C
Updated by:
Alexander C

At 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.