bing tracking image
  1. Trailer Wiring
  2. Hopkins
  3. Wiring Adapters
  4. Multi-Function Adapter
  5. 4 Flat
  6. 7 Round - Blade
Adapter 4-Pole to 7-Pole and 4-Pole

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

Item # 37185
Retail:$65.51
Our Price: $55.58
You Save: 15%
Trailer Wiring
Shipping Weight: 0.94 lbs
Add to cart
In Stock
Hopkins Wiring Adapters - 37185
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

In Use/Installed

Customer Photos

Need help with installation?
Locate installers near me
Adapter converts from 4 pole wiring on vehicle to 7-pole round plug and 4-pole flat. Additional wire leads for brake, power and accessory. Great Prices for the best trailer wiring from Hopkins. Adapter 4-Pole to 7-Pole and 4-Pole part number 37185 can be ordered online at etrailer.com or call 1-800-940-8924 for expert service.
  • All Info
  • Reviews (619)
  • Q & A (0)
  • Photos

Hopkins Trailer Wiring - 37185

  • Wiring Adapters
  • Multi-Function Adapter
  • 4 Flat
  • 7 Round - Blade
  • Plug and Lead
  • 4 Flat
  • Hopkins

Adapter converts from 4 pole wiring on vehicle to 7-pole round plug and 4-pole flat. Additional wire leads for brake, power and accessory.


Features:

  • Adapter converts from 4-pole wiring on your vehicle to 7-pole round plug and 4-pole flat wiring for trailer side
  • Adds additional wire leads for brakes, power, and accessory wiring
  • Wire functions:
    • White - ground
    • Blue - brake
    • Black - hot lead - 12 volt power supply
    • Purple - auxiliary
  • Mounting bracket included


Specs:

  • Connector measures 3" x 3"
  • Distance between vehicle mounting holes: 2-3/16"
  • 90-Day limited warranty


product detail

Wire Functions:
White: Ground
Blue: Brake
Black: "Hot" Lead - 12V power supply
Purple: Aux. - Reverse Lights etc.





Note: If you run the hot lead (black wire), you will need a circuit breaker, for example 9510 (sold separately), between the adapter and the battery itself.



47185B Adapter 4-Pole to 7-Pole and 4-Pole - Hopkins # 47185B, TAP # 37185




California residents: click here


Customer Satisfaction Score:


Customer Reviews

Adapter 4-Pole to 7-Pole and 4-Pole - 37185

Average Customer Rating:  4.8 out of 5 stars   (619 Customer Reviews)

Adapter converts from 4 pole wiring on vehicle to 7-pole round plug and 4-pole flat. Additional wire leads for brake, power and accessory.

by:

Really nice trailer wiring adapter. Very easy install. Takes about 30 minutes with all the tools needed. Drill, 7/64 bit for pilot holes to mount the bracket, flat blade screwdriver and 11/32 nut driver and two #10 self tapping metal screws with locking split washers and a couple zip ties to tidy up the wiring harness.



by:

This is a great adapter to retro fit connections on my 2011 Expedition. Simple to instal and great support from etrailer.com.



by:

Simple install and it has both the 7 way and the 4 flat plugs.



by:

Installed on our 2019 Edge ST with no significant issues. Works as expected, has reasonable required depth behind connector for ease of install, and the bracket was quite adaptable after some bending and cutting. Not impressed with the overall feel, though - plastic seems lightweight and cover hinge pin is already rusting after two winter weeks in western PA. Long term durability tbd.



by:

It was great. The instructions were not for my specific year of transit but gave me enough idea to get it done



by:

Exactly what I ordered. Easy installation. Great product.



by:

The product itself is very well made. The 4-pin connector is molded into the product and very sturdy. The 7-pin connector is held closed by a spring and has a foam gasket to keep water out. The 4-pin wiring is only about a foot long, and the additional 7-pin wiring is a bit longer. I do not have a brake controller (but do borrow a trailer with the 7-pin wiring), so I removed those wires. I also hard-wired all the connections, so I can't speak to the quality of the 4-pin vehicle connector.

The mounting bracket is thin steel, which worked well for me, as I had to bend the mounting plate to make it work for my installation. The paint on the mounting plate appears to be high quality as I bent the plate and banged it around quite a bit during install and did not nick the paint. The plate is drilled so that is can be mounted with the 7-pin hinge facing up, down, left or right.

The hardware is zinc coated, so it should hold up well to the weather. I went ahead and replaced it with SS to make sure. I also replaced the standard nuts with SS nylon lock nuts to make sure nothing would back out due to vibration. If you plan on using the supplied hardware, I would strongly suggest Loctite on the mounting nuts.

I installed this on a CX-5 with hitch # 87623, wiring adapter # C56011 and hitch cover # I-728. Over all a very clean installation. The connector is completely hidden inside the bumper, but easily accessible.



by:

I looked at so many options before deciding on the B&W hitch, but I have no regrets buying it. There is nothing that my car is suitable for towing that this thing can’t accommodate. I even use it on the front hitch of my mower to move trailers around the yard! Adjusts very easily and stows nicely (though on my Ford Edge it rides lower than I like when stowed).



by:

This was exactly what I was looking for to add to my 2017 Ford Expedition! It is an easy to install plug-n-play product to convert a factory 4-pin connector to a 4/7-pin connector.

I plugged the 4-pin in, connected the brake wire, and grounded it. Ignoring the auxiliary + power cables, everything worked on the first test. The 4-pin connection was given some dielectric and wrapped with electrical tape to keep it sealed from the elements, and the slack was zip tied to secure it.

I still need to give it some finishing touches (fill the bracket gap with some black silicone, maybe find the reverse and/or power lines), but it lets me haul my camper!



by:

Easy installation, does exactly what it is intended to do.



by:

2018 wrangler unlimited Sport S. Without trailer wiring. Completed installation today. Used a 4 flat along with a 7 pin converter. Works and fit perfectly. Very hot day and work slowly and carefully. Very satisfied . Great folks at etrailer. Great products, great quality and prices. I'm a several time repeat customer and couldn't be more satisfied.
4 pin harness Was a 56407 and the 7 pin adapter was a 37185.



by:

I recently installed the 4-pole to 7-pole adapter on my 2015 Highlander. My first install worked OK, but I ran into a ground clearance issue using the original mounting location. Etrailer suggested using a 2 1/2" mounting box to relocated the connector. Part number 18156 worked perfectly.



by:

The trailer wiring adapter was perfect and shipped in no time. Looks great on my ford ranger. Im very happy.
Was 4 flat only and now I can light my 7 way 18' trailer and have the capacity to add a brake controller (which I will add)



by:

I bought this so I can convert my dad's trailer to pull I only had a four and I needed a seven so I went and used a four to make it a seven. It's a very nice product it's got nice rubber grommets to keep everything protected.



by:

This company is amazing as they offer an incredible vast inventory of most anything one can imagine relating to trailers. They sent a nice email confirming the order and notice of being shipped, which arrived in just three days.



by:

Worked great in tandem with a new wiring harness. Still working after a year of use.



by:

Installed on a 2010 Ridgeline. Just what I needed at a great price. Install was a breeze. etrailer is the best place to find all the stuff that auto dealers rip you for. Good quality and the customer service is above reproach.



by:

Just what I need to tow an RV trailer. Also has a four flat connector. Very easy to install on the 18136 bracket.



by:

Wow after Charles great advice this was so simple to install, [online] video was point on and the hardest thing was finding the reverse wire.
Thanks so much for a good product and excellent advice, here is the pic after install!



by:

I use these adapters to install 7-way connectors on trucks that have no factory trailer wiring provisions.



by:

Does what it’s designed to. Works great



by:

2012 Chevrolet Express..Looks and works great! Easy install..2 1/8" hole saw for center, 3/16" drill bit for mounting screws. Thank you etrailer!



by:

They shipped my harness immediately to UPS. After two weeks I did not receive it, so I called the guy said it would be there Friday or Saturday, Saturday was the fourth so I knew that was gonna happen. So I waited till Thursday and called and talked to Amy E., She was great, she Found out that my harness was sent back to them. Amy re-ordered my harness, I received it on Saturday! The harness fit perfectly! So I am going to give them an excellent review! My patients was worth wait ,because it was exactly what I needed! Thank you so much Amy I appreciate all the help.



by:

Just like always from etrailer, the right product, right on time, and right on the money.



by:

Nice quality adapter harness. I would highly recommend etrailer.com


25
619
Show More Reviews

See what our Experts say about this Hopkins Trailer Wiring

  • 4-Way to 7-Way Adapter for a Trailer without Brakes
    We have exactly what you would need. The adapter part # 37185 will plug into the 4-way of your Jeep and then would convert the 4-way taillight signals to a 7-way so that you can tow your small camper trailer. This comes with the extra wires needed to make the 7-way fully functional, but you can just tape them up and out of the way since you don't need them with the exception of the white wire that should be grounded.
    view full answer...
  • Distance Between Holes On Mounting Bracket Included With Hopkins Wiring Adapter # 37185
    I pulled one of the # 37185 wiring harness kits from our warehouse and measured the mounting bracket holes. I have attached a photo of the bracket with the dimensions noted. The distance between the mounting holes is 2.25 inches. I have attached a link to a product review video you can check out.
    view full answer...
    Image 1 for
  • Troubleshooting Trailer Taillights Not Working After 37185 Adapter Install
    Connect the ground wire on the adapter and you should see the lights start to work. The purple wire being ran to the reverse light circuit will activate the reverse lockout solenoid and allow the trailer to be backed up.
    view full answer...
  • 7-Way Recommendation for a 1999 Ford Expedition
    If your trailer does not have brakes all you would need is the part # 37185 as an adapter to convert the 4-way to a 7-way.
    view full answer...
  • What Circuit to Use for Running Light Activation of Observation System Camera
    The running lights circuit would be the correct circuit to use for the camera setup you mentioned. I am not sure why it's only showing 6 volts but it should be a 12 volt circuit. This can also still be used for the running lights of your trailer as well. Normally the center pin of the 7-way is the aux/backup light circuit but this circuit isn't always active so you may have to verify that with your tow vehicle. This would be the number one pin of your picture.
    view full answer...
    Image 1 for
  • Do All Wires on Hopkins 37185 Adapter 4-Pole to 7-Pole and 4-Pole Need to Be Used
    You certainly can. The only additional wire other than the 4-pole connector that absolutely needs to be used is the white ground wire which will need to be grounded to the vehicle chassis or frame. I've linked you to a product description video featruing the # 37185 adapter.
    view full answer...
  • Can Running Light Circuit be Used to Charge Trailer Mounted Battery
    Technically yes, you could use the running light circuit to provide a maintenance charge to the trailer battery. Keep in mind though that unless it is a small 5 amp hour breakaway battery neither the running light circuit nor the 12 volt circuit if you get it working can charge UP a trailer mounted battery. There isn't enough amperage on those circuits to charge up anything other than a small breakaway battery.
    view full answer...
  • Wiring Two 6 Volt Batteries on a Trailer In Parallel or in Series
    I have included a diagram that shows the two ways in which 2 batteries can be wired together. Having two 6 volt batteries wired in parallel will produce 6 volts still but increases the capacity. The other way is to wire two 6 volt batteries in series which would double the output to 12 volts but the capacity remains the same. In either case the output side would go to the power wire on the trailer to power trailer mounted accessories.
    view full answer...
    Image 1 for
  • Determining How Many 6V Batteries Are Needed for Camping Trip
    Determining if using four 6V batteries will be overkill is really going to depend on a few things specific to your application. Factors such as the planned length of your trips, the amount of appliances (along with their amp draw) you will need to have powered, the need for larger appliances like an Ac, etc will all play a part in deciding just how much power you need. Four batteries will essentially double your amp hours (when compared to two). You will really just need to find out the...
    view full answer...
  • Which Pin on 7-Way Trailer Connector Carries 12V Charge
    On a vehicle 7-way type trailer socket the wiring configuration can be in several different formats. If you refer to the linked article you'll be able to see photos of the common function assignments for each pin. Usually the socket pin at the 1-o-clock position wil carry the 12V auxiliary power feed for the trailer battery. Most vehicle wiring will have this power feed controlled by the ignition key to avoid accidentally discharging the vehicle battery.
    view full answer...
  • Can I use 4-Way to 7-Way Adapter Part 37185 on my 2006 Volvo XC90
    If you were to use it just for trailer light functions it would work fine. You would plug in the the 4-Way you currently have, then attach the ground wire to the XC90 frame. The other 3 wires are for reverse lights, trailer brakes and a power source. If you do not need any of these functions, you can tape these leads up and out of the way. Part # 37185 is not vehicle specific and can be wired to virtually any vehicle.
    view full answer...
  • Troubleshooting Why Only 4-Way of 7-Way Adapter part # 37185 is Active
    If the 4-way of the Hopkins Adapter part # 37185 is working but the 7-way isn't that would indicate that the white ground wire that came with a ring terminal is not grounded properly. Try verifying that it's grounding properly and you'll most likely fix the issue. Otherwise the adapter has a problem and would need to be replaced but this is incredibly rare.
    view full answer...
  • Replacement Housing For Hopkins Adapter 4-Pole to 7-Pole and 4-Pole socket
    I spoke with Hopkins and they confirmed the housing is not replaceable, the only option is to replace the entire adapter with the Adapter 4-Pole to 7-Pole and 4-Pole # 37185.
    view full answer...
  • Does 12 Volt Circuit (Black Wire) have to be Used when Installing 4- to 7-Pole Adapter 37185
    It does not. For the 4-Pole to 7-Pole adapter # 37185 the black 12 volt circuit wire does not have to be connected for the adapter to work. You just won't have that function available on the connector. If the trailer does not require the 12 volt circuit then it isn't a problem. Apart from plugging in the 4-Way to the adapter the only other wire that has to be connected is the white ground wire.
    view full answer...
  • Adding 7-Way to 2007 Ford F-150 With 4-Way
    Since your RV has a 7-way, in order to utilize all of its functions and have it work with your 2007 Ford F-150, you will need to add a 7-way to your truck. One of those functions is for electric brakes, so you are going to need a trailer brake controller, assuming your RV has electric brakes. You mentioned you already have a 4-way, which is the factory 4-flat on your truck, so the only other thing you need is the Adapter # 37185. Your 2007 Ford F-150 will have wires already run which...
    view full answer...
  • Troubleshooting Brake Controller Losing Connection with Running Lights Activated
    It definitely sounds like there is a ground issue somewhere on your Ford F-150 or trailer. A weak ground will usually show itself when additional power draw is put on the system, such as in your case when activating the running lights on top of the signal lights and brake output signal. I recommend making sure your ground connections on the trailer are secured to clean, bare metal surfaces. You can check the ground wires from the brake assemblies as well. You may want to try and move...
    view full answer...
  • Recommended Wiring Harness for a 2005 Ford F-150 with Factory 4-Way
    What I recommend for your 2005 Ford F-150 is to install a Hopkins 7-way adapter # 37185 and splice the 12V power wire, brake controller wire and reverse light wire into the wiring at the back of your F-150. Take a look at the informative article I included. Your current 4-way connector will plug into the Hopkins adapter # 37185. Unfortunately, there currently isn't an aftermarket option to simply plug in a 4-way to a 7-way adapter for your 2005 Ford F-150. I also included a couple video...
    view full answer...
  • Will Hopkins 7-Way Fit 7-Way of 2020 Toyota Tundra
    All 7-way connectors out there are going to plug right into the 7-way of the 2020 Toyota Tundra that you mentioned. Thankfully there is only one design and all of the companies make their 7-ways to fit that exact design. If you have a vehicle or trailer that is wired differently it would be just a matter of swapping the wiring like you mentioned. You can't rotate the 7-way and install it differently as the design does not allow for that.
    view full answer...
  • How To Convert a 4-Way On a 2011 Ford Expedition To a 7-Way Trailer Connector
    In order to convert the 4-way trailer connector on a 2011 Ford Expedition into a 7-way trailer connector all you will need is the Adapter 4-Pole to 7-Pole and 4-Pole part # 37185. The two 4-ways will plug into one another then you'll need to make a few more connections which can be found outlined in the photo below.
    view full answer...
    Image 1 for
  • Going from 4-Way to 7-Way on 1996 Ford Super Duty
    To adapt the 4-way of your 1996 Ford Super Duty to a 7-way you'd need to use the 7-way adapter part # 37185. The 4-way would plug right in and the trailer lighting functions would all be on the 7-way instead of the 4-way.
    view full answer...
  • How to Wire 2 New Batteries to a 1993 Holiday Rambler 5th Wheel Trailer
    It depends on how you want to connect the batteries; in series or in parallel. Batteries that are wired in series will double the output voltage and keeps capacity the same. So for example if you are using 2 identical 12 volt batteries connected in series the output voltage would be 24 volts and the amp hour rating would be whatever it says on one of the batteries. If the same 2 batteries were connected in parallel they would be putting out 12 volts but the capacity would be doubled. I...
    view full answer...
    Image 1 for
  • Where is the Red and Blue Wires on a 1994 Ford F-150 for Installing a 4-Way to 7-Way Adapter
    The connector you are looking for that has the red and blue wires is in the driver side frame rail near the rear of the vehicle. Check out the video I attached that shows where it is at right around the 2 minute mark. I also attached a picture of what the connector will look like.
    view full answer...
    Image 1 for
  • Recommended 7-Pole And 4-Way Adapter for 2000 Ford F-350
    The trailer connector I recommend is part # 37185. This connector can be installed with your existing 4-way connector, or you can remove the 4-way connector and hardwire the adapter that will give you a working 7-way and 4-way trailer connector. I have attached a link to a helpful article about trailer wiring you can check out.
    view full answer...
  • How to Wire Two 6 Volt Batteries Together so that the Output is 12 Volts
    If the batteries are wired in series, the positive terminal of one battery will be connected to the negative terminal of the other. This would double the output of the batteries, assuming each battery is a 6 volt, wiring the batteries in series would provide 12 volts of output. I attached a picture that shows the way two batteries are typically wired together.
    view full answer...
    Image 1 for


< Previous
123. . .87



Do you have a question about this Trailer Wiring?


Info for this part was:

Employee Joe V
Test Fit:
Joe V
Employee Nicholas E
Test Fit:
Nicholas E
Employee Shane T
Test Fit:
Shane T
Employee Randy B
Test Fit:
Randy B
Employee Joe B
Test Fit:
Joe B
Employee Jared G
Test Fit:
Jared G
Employee Brent H
Test Fit:
Brent H
Employee Shane H
Test Fit:
Shane H
Employee Robert C
Test Fit:
Robert C
Employee Conner L
Test Fit:
Conner L
Employee David F
Test Fit:
David F
Employee Bradley B
Test Fit:
Bradley B
Employee Jackie C
Expert Research:
Jackie C
Employee Mike L
Expert Research:
Mike L
Employee Sarah L
Expert Research:
Sarah L
Employee Robert G
Expert Research:
Robert G
Employee Patrick B
Expert Research:
Patrick B
Employee Michael H
Expert Research:
Michael H
Employee Jeff D
Expert Research:
Jeff D
Employee Reno H
Expert Research:
Reno H
Employee Jameson C
Expert Research:
Jameson C
Employee John H
Expert Research:
John H
Employee Brandon M
Expert Research:
Brandon M
Employee Adam R
Expert Research:
Adam R
Employee Lori W
Expert Research:
Lori W
Employee Jeffrey L
Expert Research:
Jeffrey L
Employee Zack K
Video Edited:
Zack K
Employee Andrew K
Video Edited:
Andrew K
Employee Joshua S
Video Edited:
Joshua S
Employee Jacob T
Video Edited:
Jacob T
Employee Andrew L
Video Edited:
Andrew L
Employee Dustin K
Video Edited:
Dustin K
Employee Sue W
Video Edited:
Sue W
Employee Chris R
Video Edited:
Chris R
Employee Zach D
Video Edited:
Zach D
Employee Adele M
Updated by:
Adele M
Employee Wilson B
Updated by:
Wilson B
Employee Alexander C
Updated by:
Alexander C
Employee Hannah L
Updated by:
Hannah L
Employee Kathleen M
Video by:
Kathleen M
Employee Alan C
Video by:
Alan C
Employee Jonathan Y
Video by:
Jonathan Y
Employee Thomas T
Video by:
Thomas T

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.