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Adapter 7-Pole to 4-Pole and 5-Pole

Adapter 7-Pole to 4-Pole and 5-Pole

Item # 37385
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Trailer Wiring
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Adapter 7-Pole to 4-Pole and 5-Pole Multi-Function Adapter 37385
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Lowest Prices for the best trailer wiring from Hopkins. Adapter 7-Pole to 4-Pole and 5-Pole part number 37385 can be ordered online at or call 1-636-306-4830 for expert service.
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Hopkins Trailer Wiring - 37385

  • Wiring Adapters
  • Multi-Function Adapter
  • 4 Flat
  • 5 Flat
  • Plug Only
  • 7 Round - Blade
  • Hopkins


  • Wiring Adapter - converts the 7-way trailer connector on the vehicle to a 4-way or 5-way connector to match the trailer

If your truck has the connector on the left, and your trailer has one of the connectors on the right, you will want this adapter.
30300 18004
Vehicle End Trailer Ends

47385 Adapter 7 Pole to 4 Pole and 5 Pole - TAP # 37385

California residents: click here

Video of Adapter 7-Pole to 4-Pole and 5-Pole

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

Video Transcript for Hopkins Wiring - Wiring Adapters - 37385 Review

Today we're going to review part number 37385. This is the Hopkins 7-pole to 4-pole and 5-pole adapter. This is a wiring adapter that will convert the 7-way trailer connector on your vehicle to either a 4-way or a 5-way connector to match the trailer. As you can see the dust covers are included to protect them if you're not using the connector. Basically you'll notice when you plug this into the 7-way it'll give you your lighting functions on the 4-way. It has the ground, it gives you your tail light function, your left turn and brake, and your right turn and brake. On the 5-way, when you plug that in it will give you all the same functions of the 4-way but the extra one is for the reverse light circuit.

Lots of times on a boat trailer will use a 5-way so you'll be able to use that reverse light circuit for the surge actuator on the trailer itself. That should do it for the review on part number 37385, the Hopkins 7-pole to 4-pole and 5-pole adapter. .

Customer Satisfaction Score:

Customer Reviews

Adapter 7-Pole to 4-Pole and 5-Pole - 37385

Average Customer Rating:  4.8 out of 5 stars   (105 Customer Reviews)


Junk. Did not work new out of the box

You mentioned that it did not work as new out of the box and I wanted to see if you could explain in more detail what happened.
-- Etrailer Expert Jenny N - 11/08/2022
I opened it new out of the box, plugged it into my trailer and vehicle and got no lights, plugged a different adapter in and instantly had trailer lights. The plug did not work brand new out of the package its first use. hope this clarifies ,
-- comment by: John - 11/08/2022
It does, thank for answering. I can send warranty information to you if you would like to have it replaced.
-- Etrailer Expert Jenny N - 11/08/2022


This was my second order. Great service! You have the hard to find parts and expeditiously ship them. I will highly recommend etrailer to others.


Workedcjust fine.


In my quest for a 7 pin to 4 pin connector to operate lights on my luggage rack my search led me to etrailer. Initially I spoke with Derek who was very helpful and sent me a connector that was 7 to 5 pin as that's what I thought I had. Turns out I was wrong so I called back to order a 7 to 4. This time I found Ashley and she quickly mailed me the 7 to 4.
These two employees were most helpful and very courteous in my dealings with them I'm happy to recommend etrailer for these kinds of products. Give them a try!

Works fine. Only used it a few times but no problems.
Jim L - 07/29/2018


These plugs work great. I use it for my boat trailer (5 Plug), Jetski trailer (4 Plug) and a Car Hauler Trailer (7-way). Very simple to use. Highly recommend it you use multiple trailers with different plugs and braking systems.

Everything is still working great with no issues!!
Ted - 09/10/2020


Needed one


Product was delivered in a timely fashion and matched the part ordered. Quality was excellent and provided the features per price point that was desired. So far, no problems in use. It is now part of my basic trailering kit. Other products are available that have more features but they are larger and cost more. For my use this is right on. Product support and useful information from etrailer is consistently excellent.

After one year the wiring adapter continues to work well. I would not change my original review.
Capt.Wanabe - 07/23/2018


Provides a quick and simple solution for connecting a trailer with a flat-4 or flat-5 plug to my truck with its round 7-way plug.

We recently towed a rental trailer from Maryland to New Mexico. This connector worked perfectly!
Robin N - 07/21/2017


The adapter fit tightly and worked well. Be careful attaching and detaching the trailer harness so, you don't bend the bottom metal, male connector.

Everything installed correctly the first time and worked on my 2011 Honda Pilot. What a relief. It took me about 2.5 hrs because, I had to figure out fasteners for the bumper, existing wiring harness, etc. so I didn't break anything. Make sure you have a center punch, sharp metal drill bits and oil to pilot holes for self tapping screws. I am very happy with the harness and adapter.


Nice quality. Convenient all in one ada pter.


Was exited when I found this on etrailer's website...I have 2 different trailers with 2 differents light harness connectors. This works need to switch out or have two or more adaptors in truck!! Highly recommend!


Exact replacement for the one I lost, had no problem finding it at etrailer since I had previously bought hard to find parts I needed when replacing worn parts on my boat trailer. Thanks etrailer.

Working great, I am causious about not losing it again, thanks again.
Jimmy - 04/07/2019


Overall...much better than going through the dealership for the sake of time and money. The online videos hit all they key points and steps bit there was some mechanical ingenuity required on my part. Mounting the bracket was the most challenging part to install and it was correctly represented in other reviews.

Personally, I wanted the 7 pin connector flush to the bumper and had to bend the mounting bracket and cut out the plastic bumper to get a tight fit. Looking back however, I think that if I would have cut out just enough of the bumper to accommodate the angle of the mounting bracket (when attached to the frame) then I would have still achieved both a solid connection and clean, professional look.

All in all, I'm very satisfied with the product and instructions received from e Trailer and staff.


It was great and worked exactly as it was supposed to until my dog pulled it out of the receptacle and chewed it to bits.
I put an external tire carrier on my car and was using the three hole side to power my relocated license plate.
The rig lasted through all sorts of weather and terrain like a champ. I got about 9 months out of it before it was devoured. I'm sure it would have lasted for years if not for the >-< dog.


This adapter works perfect. It easily installs into the round 7 pin connector. The connector worked as all lights were lit and I was able to back my boat trailer into position with no problems. The 5 flat is used for the inclusion of the surge brakes on my boat trailer. I would recommend this to anyone needing the conversion adapter.


As always, product arrived quickly and well-packed. Good quality and is working well on my vehicle. etrailer can be counted on for quality and customer service.

No problems, never give it a second thought. Can depend on it to do the job.
David - 03/28/2020


This trailer light adapter allows me to haul 2 different trailer with one vehicle. Delivery was in 3 days and I also purchased a 5 wire trailer wiring harness to match


The wiring kit fits perfectly. I had a small problem with the operation of the brakes on my trailer but a quick call to the great service department and my problem was quickly rectified. I will do business again.


Good product. Works well and is very convenient to have both 4 and 5 pin connectors. Only issue is dust cover on 5 pin sticks to ground pin when you pull it off with the tab and can bend the ground pin.


Just what I needed, have a boat and two wheel trailer with different plugs , ordered the weather tech mud flats also for my 2011 gmc 1500, they were easy to install and look great, all items where to me in three days. Great job etrailer


Fits the round plug on the vehicle perfectly. Haven't hooked it up to the flat wire yet, but assume it should be fine. Getting this adapter with the covers for the 4 & 5 flat is absolutely the right way to go. I'm towing a 5500 lb boat with surge brakes.
Jesse did an outstanding job of helping me.


The Adapter made a quick and easy connection between my truck and the trailer. All lights functioned properly.

Great adapter at a great price.


I find this adaptor to be very useful as I own and frequently tow, different size trailers all with different plug connectors. Nothing is worse than not having the right connection to make your trailer connection.


I'm not one to take the time to write reviews but I just got to say this company really impressed me with the information available on their site and with the terrific service when calling them on the phone. In my experience this level of customer service is very hard to find today. Keep up the great work and thanks again for your time and help. I'll definitely recommend you and will be back should I have any needs in the future!


Fantastic. Elliminates need for 2 separate harnesses. Many trucks already have a 7 pole connector and a 4 pole connector but nobody has a 5 pole connector so this kills 3 birds with one plug.

Show More Reviews

See what our Experts say about this Hopkins Trailer Wiring

  • Troubleshooting a Trailer that Blows Vehicle Tail Light Fuses and Sparks When Touched to Hitch Ball
    It sounds like there is a 12 volt short on your trailer. The spark you are seeing is because your trailer frame has 12 volts running through it and its grounding to the ball and sparking. It sounds like its the running light circuit since that would most likely be the circuit that would be left on if you were hitching or unhitching a trailer. This would also explain why your tail light fuse is blowing. You should go over the running light circuit very carefully and see if there is any...
    view full answer...
  • Brake and Turn Signals Are Not Working On Trailer Towed by a 2006 Honda Ridgeline
    If your 2006 Honda Ridgeline came with a factory 7-Way trailer connector and it was working before but now it is not, check the vehicle owners manual for the fuse/relay locations related to the tow package wiring to see if any need to be replaced. That is the most likely cause. If the trailer wiring was added aftermarket then there could be a ground problem or a dirty/corroded connector. Check the grounding location and make sure that it is attached to a clean and corrosion free bare metal...
    view full answer...
  • Troubleshooting a Boat Trailer that the Left Light Assembly Does Not Function
    It sounds like you have a bad ground on the left side light assembly. That would explain why all functions of that assembly are not working. I would check the condition of the ground and make sure its attached to a clean metal surface. Or if the assembly grounds through the installation brackets you would want to make sure its attached to a clean metal surface. There could also be corrosion in the trailer harness plug, you might check for that and clean as necessary. I also attached an...
    view full answer...
  • Troubleshooting a TrailStar Trailer that Running Lights Only Work on the Left Side
    It sounds like the problem is in the way your left side tail light is wired, does your left turn signal work? I would go over the wiring and make sure that the brake/turn signal wire is attached to the correct circuit of the light and the tail light function is connected to the other. It almost seems like you might have both trailer light circuits run to one circuit of the tail light. I attached an FAQ article on trailer wiring for you to check out also that might be helpful.
    view full answer...
  • Will Hopkins Adapter # 37385 accept two 4-pole flat connectors simultaneously
    Yes, you can use two 4-pole flat connectors into the Hopkins # 37385. I spoke with my technical contact at Hopkins and he said that many, many people are using this adapter to run two sets of lights simultaneously so you will be fine with this as well. Even though you can run both at the same time, you also want to make sure you do not overload the circuit of the adapter, however, by running LED lights you will be fine.
    view full answer...
  • Troubleshooting a Trailer for no Left Turn Signal Functions
    It sounds like the problem is that the ground on the left side is bad. If the light grounds through the mounting hardware then you you will want to make sure the light is attached to a clean metal surface. I would remove the light assembly and check to make there is no rust or corrosion and fix as necessary. If the assembly grounds through a wire I would recommend you trace that wire back to where it terminates to confirm that where it attaches is clean and free of rust and corrosion as...
    view full answer...
  • How Does Running Light Signal Get to Both Sides of Trailer if there is Just 1 Running Light Circuit
    Trailers have combined wiring which means the brake lights and turn signals share a circuit on each side and there is only one tail light circuit. The tail light circuit is then split to go to both sides of the trailer. I have included a link to our trailer wiring FAQ article that covers the various types of trailer and vehicle side connectors for you.
    view full answer...
  • Is Any Additional Wiring Needed to Use a 4-or 5-Way Trailer Connector with a 7 to 4/5-Way Adapter
    By using adapter # 37385 in your truck side 7-Way you will be able to plug in a 4-Way or 5-Way flat and it will work without any additional wiring needed. In order for the electric reverse lockout to work the center pin on the 7-Way must be active (connected to the reverse light circuit).
    view full answer...
  • Troubleshooting Re-Wired Flashers and Hazards on a Dump Trailer With Continually Blown Fuses
    The most likely cause is a short in your trailer wiring. However, before you start tracing circuits, hook your tow vehicle up to another working trailer to verify that the issue is not on the tow vehicle side. If your tow vehicle worked fine with the other trailer then the problem is on the trailer side. Visually check the wiring you just put on, looking for a small nick in the wire insulation that is allowing the copper wire to short out on the trailer frame. To fix the nick you can...
    view full answer...
  • Trailer Running Lights Will Not Work and Blow Fuse on Truck
    If it is the tow package running light fuse that is blowing then there is most likely a short in the trailer wiring or in the trailer or vehicle side connector. What you will want to do first is make sure both the vehicle side and trailer side connectors are clean and free of corrosion inside and out. Next make sure the main trailer connector ground and the grounds for all of the lights are attached to clean and corrosion free bare metal surfaces. Then you will need to trace the wiring...
    view full answer...
  • Troubleshooting Replacement Tail Light Wiring Install on a 1993 Prowler Trailer
    I would first use a circuit tester like our part # 3808 to test the wires you are trying to run to the replacement light assemblies so that you can verify that all of the functions are working properly and that you know what wires need to run where. Without knowing what light assembly you have it is hard to say what wires will need to be run where. If you find that any of the circuits are not working on your trailer wiring you would want to trace the wiring back up to the 4-way looking...
    view full answer...
  • Right Turn Signal Does Not Work with Tail Lights On
    I believe the problem is a poor ground connection either on the trailer or with the vehicle side trailer connector. A poor ground is typically the culprit when certain light functions work sometimes but not all the time. The first step I would take is to check all of the ground connections for the vehicle side trailer connector, trailer side connector and for each of the trailer lights, including the marker lights and the license plate light. The ground wires should be attached to a...
    view full answer...
  • Troubleshooting a Left Trailer Light Not Functioning
    First I would check the ground of the left tail light assembly. It sounds like the light is not getting a strong enough ground and because of that it is not illuminating. You will want to make sure that it is connected to a clean metal surface. If it grounds through the mounting hardware then you will need to make sure it is mounted to a clean metal surface. Next check the back of your trailer connector on your tow vehicle, look for corrosion or exposed wire that could be causing a short...
    view full answer...
  • Malfunctioning Turn Signals, Clearance, and Tail Lights on 6 by 12 Foot Trailer
    It sounds like you have an improper ground. This is confirmed when the maximum amperage is on the system (with headlights on), and the lights do not work at all. This indicates a grounding problem. This ground issue could be in a couple of different places; it could be in the vehicle connection plug, a ground wire on the trailer itself, or on one of the trailer lights that require grounding through a mounting location. Since you said you checked your truck connection I would check the...
    view full answer...
  • Will Hopkins 7-Way to 4/5-Way Adapter Fit a 2012 GMC Sierra 1500 with Factory Tow Package
    Yes the Hopkins adapter # 37385 (AKA 47385) will fit the standard 7-Way blade style connector on your 2012 GMC Sierra. This adapter provides the basic lighting functions for a 4 and 5-Way connector and reverse signal for a 5-Way trailer connector.
    view full answer...
  • After Installing New Trailer Lights and Wiring, Trailer Lights Will Not Work Properly
    This sounds like a ground problem and possibly a wiring issue. The lights should have something that indicates the wire functions on the back of the housing so it is easy to check those. There should be one wire for the turn signal/brake lights, and one wire for running lights. Then there will be either a separate ground wire or the lights ground through the mounting studs. When there is a weak ground not all functions will work. A weak or bad ground can be caused by corrosion at the grounding...
    view full answer...
  • Troubleshooting Left Taillight Circuit Not Activating After Checking Grounds and Replacing 4-Way
    Somewhere on the running light circuit on the left side of the trailer there is a short. It sounds like you have started at both ends of the trailer by replacing the 4-way and checking the ground of the light assembly. So its time for you to check what lies between the connector and the assembly; the wiring. If you have a wishbone wiring system where two wire come out of the running light circuit on your 4-way then you need to trace the wiring from the connector all the way back to the...
    view full answer...
  • What is the 5th Pole Used for in 7-Way to 5/4-Way Adpater 37385
    The fifth pole on 7-Way to 5/4-Way adapter is not wired for electric brakes. It is wired for reverse lights.
    view full answer...
  • Can 7-Way Adapter be Used with a 2002 Chevy Silverado
    Yes the Trailer Connector Adapter, part # 37385, will work with the factory 7-Way on a 2002 Chevy Silverado 2500. You will not retain the 7-Way, but you will have the option to use 5-Ways, or 4-Ways.
    view full answer...
  • Will The 7 Pole to 4 Pole Adapter Fit My 2007 Toyota Tacoma
    The adapter that you have selected, Adapter 7 pole to 4 Pole and 5 Pole, part # 37385 will work perfectly for your 2007 Toyota Tacoma with 7 way plug. It will convert your 7-way to a 4-way or 5-way with your flat trailer connector.
    view full answer...
  • Troubleshooting Trailer Brake Lights not Working When Running Lights are On
    It sounds like you might have a bad ground connection. When the taillights are on, that is when there is the most power draw on the system. Stepping on the brakes would then add more and this is when a ground problem will usually show up. The taillights usually ground through the mounting bolts on trailers. Check for a bad ground, loose connection, and dirt and corrosion. Any of those can cause this problem. Also check the light bracket connections to the trailer frame as lights can ground...
    view full answer...
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  • Will Adapter 7 Pole to 4 Pole and 5 Pole Work On My 2010 Toyota Tundra With Tow Package
    If your 2010 Toyota Tundra is equipped with tow package and factory 7-way on the back of your truck then yes the Adapter 7 Pole to 4 Pole and 5 Pole, part # 37385 will match up perfectly. The 5 pin flat connector on your trailer will plug directly into the 5 pin outlet on part # 37385.
    view full answer...
  • 7 Pole to 4 Pole and 5 Pole Adapter # 37385 for a 2011 Chevy Silverado Northstar Camper or Boat
    This Adapter 7 Pole to 4 Pole and 5 Pole, part # 37385, is designed to plug into a 7 way trailer connector and convert it to either a 4 way or 5 way connector. As long as your Northstar Pickup camper and boat trailer have either a 4 or 5 way flat connector this should work perfectly for you.
    view full answer...
  • Can The 4-Way and 5-Way Connector of The Hopkins Adapter # 37385 Be Used Simultaneously
    I contacted our representative at Hopkins and he informed me that you can use both the 4-way and 5-way plugs of the Hopkins Adapter # 37385, at the same time without a problem. In your setup you would not need the extra pole on the 5-way as it is for brake function on a trailer with surge brakes. You will want to be cautious not to add so many lights that you overload the vehicle wiring.
    view full answer...

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