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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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Adapter 7-Pole to 4-Pole and 5-Pole Multi-Function Adapter 37385
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Great 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 1-800-940-8924 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 7-Pole to 4-Pole and 5-Pole Adapter Review

Hey everybody, Ryan here at etrailer. Today we're gonna be checking out the Hopkins trailer wiring adaptor plug. So this is gonna go from a seven-way round not only to a four-way flat, but also a five-way flat. So let's check it out. And if your vehicle has a seven-way round type connector like mine does here, and you have to tow a trailer that has a four-way flat or five-way flat, this is gonna allow you to do that. So the way this will work is you'll plug into your seven-way round connector and then choose the appropriate type of wiring.

So we're hooked up to a small little fishing boat here. It has a four-way flat. We can open up that cap, take our trailer wiring, and plug right into it, and that's gonna allow all the signals to transfer back to our trailer, giving us all the lighting signals to keep us safe and legal. And what a lot of people like about this one is this honestly gives you the ability to tow or hook up to, wiring-wise, just about any trailer. So let's say maybe you have a utility trailer that has a four-way flat and then maybe a boat trailer that has brakes or something on it that has a five-way flat.

Having this one adapter is gonna allow you to pair up to all those different types and not have to keep two or three of these rolling around in your glove box or whatever the case is. These signals that this is gonna send back for our four-way flat will be your taillights, your brake lights, and your turn signals. So you have all your bases covered there. Five-way flat is gonna send out all those same lighting functions except that fifth pen is gonna be for a reverse light or backup circuit. Generally you'd see that on marine or boat trailers that are a little bit larger that have surge brakes, or even if maybe you have a utility trailer and you want to set up reverse lights on it, something along those lines.

That's where the five-way flat is gonna come into play. As far as the construction quality goes, I feel like it's pretty well-made. Feels like it's thick plastic, don't feel like a piece of junk by any means. It does fit nice and tight, at least into my seven-way. So that's good.

You know, don't worry about it having a loose connection or something, but I like how they give you the caps too because if you want to leave this thing in here, say if you tow a lot or something, or just don't feel like storing it inside the vehicle, at least you can keep those terminals protected against corrosion and whatnot. And honestly, from time to time anyway, it's not a bad idea to apply di-electric grease to 'em. And that holds true for your trailer end as well. Just keeps it in better shape and you can expect to get a little more life out of it. Something that I have ran into the past with using certain types of adapters is every trailer end might be a little bit different. These you don't see too often, but they are out there where they're kind of boxed in and in the past I've had issues getting 'em to hook up. And with this particular one, that's really not the case. It still fits right over it and creates a good tight seal. We do have a trailer here that has a five-way flat. And just to kind of show that off, you don't want to give the four-way all the love today. We'll just show you how it works too. You know, pretty standard connector and don't run into any issues in terms of getting that plugged in into our adapter plug. Other than that, at the end of the day, you know a great solution for those of you that have different types of trailers or different types of wiring, or if you're just unsure of what you might be pulling in the future. This is gonna allow you to hook up to all those different types for the most part. So can't really ask for too much more. But that'll about do it for our look-at of the Hopkins seven to five and four-way adaptor plug.

Customer Satisfaction Score:

Customer Reviews

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

Average Customer Rating:  4.8 out of 5 stars   (107 Customer Reviews)


Wish I would have found this earlier, Super addition to my towing kit in my Atlas


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


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


Needed one


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.


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


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.


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


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.


Nice quality. Convenient all in one ada pter.


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


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 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.


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


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.


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

Great adapter at a great price.


Was very happy with the Adapter. After a year of using now, i have had no issues. Would recommend for any trailer needs.


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

  • Diagnosing Lighting Problem on Trailer Towed by 1995 GMC 1500 Pickup
    If your truck is equipped with the factory tow package, there will indeed be fuses that protect the towing circuits that might be blown. Your owners manual or the legend printed on the lid of the fuse box should list the fuse location that you are looking for. If you do find and replace a blown fuse, you will then need to closely examine the wiring on the trailer to locate the short that caused the fuse to blow. Make sure the connector on the trailer is not damaged or corroded. Trace each...
    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...
  • Only Left Side Brake and Turn Signals Working on Boat Trailer
    This sounds like a ground problem. A loose, broken, or corroded ground connection can cause all sorts of unwanted problems for electrical components including trailer taillights. I would start with checking for a proper ground at the taillight itself. Trailer tail lights can be grounded in one of two ways. The first way is the tail light assemblies can be grounded by a separate wire coming out of the back of the tail light and attached to the trailers frame. The second way is the tail...
    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...
  • Rental Trailer Caused Fuse to Blow Now Trailer Lights Won't Work After Replacing Fuse
    It sounds like the rental trailer had a short and caused the fuse to blow. It could have actually caused more than one fuse to blow (or a relay if your vehicle also uses relays for the tow package wiring). Use the vehicle owner's manual to find all fuse and relay locations related to the tow package wiring to see if there is something else that needs to be replaced. To test the vehicle side trailer wiring you can follow the help article I have linked to the right.
    view full answer...
  • Would the 4 and 5-Way Pins of the # 37385 Both Be Active at the Same Time
    Yes, the 4-way and 5-way pins of the part # 37385 will both be active when the adapter is plugged into a 7-way. You could use both at the same time.
    view full answer...
  • Troubleshooting E1 Error Code on a Hopkins Brake Controller
    The E1 error code indicates a trailer is not connected. If you ever get this error and the trailer IS connected a probable cause is a dirty trailer connector. Check the trailer connector on the trailer and on the vehicle. Clean out any dirt or corrosion. Corrosion can build up behind the connectors where the wires attach as well. 99% of the time this code is seen all you have to do is clean the trailer connector pins. Especially if it is intermittent like yours.
    view full answer...
  • Trailer lights
    It sounds like there is either fuses or relays blown on the truck or the trailer connector on the truck side has corrosion in or on it. Checking the fuses and relays is easy. Just locate the tow package fuses/relays using the owner's manual or the legends on the fuse panel lids (many vehicles have fuse panels in the cab as well). For a relay the easiest way to check for a bad one is to use a known good one in its place. Inspect the trailer connector and make sure it is clean and free of...
    view full answer...
  • No Running Light Power on Truck Side 4-Way Trailer Connector
    If there is no power on the truck side trailer connector running light circuit then it could be a blown tow package fuse or a loose connection, damaged wire, or ground issue. If the connector on the truck is factory then consult the owner's manual to locate the fuse related to the tow package running light circuit. You can also check the vehicle side connector for corrosion inside, where the wires attach, and outside on the pins. Inspect the wiring as best as you can from the connector...
    view full answer...
  • Parking Lights on Trailer Are Faint But Have Proper Voltage
    With proper voltage coming out of your plug, we know the vehicle end is working properly. The problem with the tail light being faint in your tester may be an issue with the tester since you know you have 12 volts at the plug. If the running lights are faint when your trailer is hooked up, I'd check the connection point to your trailer for corrosion and double check the ground on your trailer near the tongue and also any ground that is a direct connection to the lights to ensure it...
    view full answer...
  • Which Fuse Number Carries Trailer Running Light Circuit on 2014 Chevy Silverado
    From the research I did on your vehicle it looks like the position 15 of the mini fuse section has the trailer running light circuit.
    view full answer...
  • Troubleshooting Boat Trailer LIghts that Don't Function Properly when Headlights are On
    Most likely the problem is an insufficient ground on the trailer's wiring. Anytime you get bizarre trailer lighting functions like what you described when the headlights are on the problem is almost exclusively that the trailer light grounds can't handle the additional load put on the wiring when the headlights are on. Make sure that the trailer side connector are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare...
    view full answer...
  • Troubleshooting Trailer Blinkers That Stay On or Don't Come On at all
    First thing you should do at this point is test the 4-way of the wiring harness with a circuit tester part # 3808 for voltage on all of the right pins when the taillight signals are being applied. Just like in the video I attached. If the voltage checks out there but the trailer lights still don't function right then the problem is on the trailer wiring. That would mean that problem is either due to a ground issue or a short issue. Make sure that the trailer side connector are clean and...
    view full answer...
  • Troubleshooting Trailer Wiring Where Brake Lights Come On with Head Lights
    It sounds like the running light and brake light circuit of your setup is shorting out together somewhere on your setup. Either on the tractor side of the connector or on the trailer. You can test the trailer connector with your circuit tester to see if both the pins are operating independently of each other like they should. If they both are coming on when the headlights are on then the problem is on the truck side of the wiring and you would need to look for a short somewhere before...
    view full answer...
  • Trailer Brakes Come On when Tow Vehicle Automatic Headlights Turn On
    If you are using adapters to match the vehicle side connectors with the trailer side connector it could be that the adapter or the trailer side connector is not wired up correctly to match what is required. I have included a link to a help article that shows how vehicle and trailer side connectors should be pinned out so you can check yours. If the vehicles have brake controllers it could be that the brake controller red wire is not attached to the correct brake switch wire. For hardwire...
    view full answer...
  • Plugging in a Tow Dolly and Magnetic Light Kit to the Same 7-Way Trailer Connector
    You technically could use # 37385 because a 4-Way flat connector will plug into a 5-Way flat receptacle. The last pin just isn't used on the 5-Way end. The only problem is that you have to make sure that the combined power draw is not too much for the tow package wiring on the tow vehicle. The other thing you can do is cut off the 4-Way on the magnetic kit and just splice it into the wiring for the tow dolly. But you would still need to be careful of the power draw. I do not anticipate...
    view full answer...
  • Troubleshooting Trailer Wiring that Works with One Truck But Not Another
    It could be a somewhat weak ground on the trailer that allows the lights to work with one vehicle but not with another. What you can try doing is running a ground wire from each of the light assemblies back to the main ground of the trailer. That should help especially if you have a fold away style coupler on your boat trailer.
    view full answer...
  • Troubleshooting Trailer Taillights that Stop Working When Brakes are Applied
    Sounds like you either have a weak ground on your trailer taillights or the lights themselves are drawing too much amperage and it's causing the circuit to just shut off. Typically a fuse would get blown if this were the case so most likely it's a weak ground. Also, be sure to check the function with the engine of the tow vehicle running as the additional amperage of the alternator running will give the trailer circuits a bit more juice.
    view full answer...
  • 7-Way to 4 and 5-Way Adapter # 37385 for the 2005 Toyota Sequoia
    Yes, the Adapter 7 Pole to 4 Pole and 5 Pole, item # 37385, will work with the 7-Way connector on your 2005 Toyota Sequoia. If you have a trailer with surge breaks that uses the 5-way connector you will need to make sure the center pole on your vehicle is wired to the backup light circuit. If it is not wired this way, you will need to splice into the backup circuit behind the taillight and wire to the center pole inside your vehicle connector.
    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...

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