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Curt Trailer Connector Adapter - 4-Way Flat to 5-Way Flat - Vehicle End

Curt Trailer Connector Adapter - 4-Way Flat to 5-Way Flat - Vehicle End

Item # C57187
Our Price: $10.35
Trailer Wiring
Shipping Weight: 0.24 lbs
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Convert your vehicle's 4-way flat trailer connector to a 5-way flat. Plug the 4-pole connector into your vehicle and connect the wire leads to get the electric brake function. Great Prices for the best trailer wiring from CURT. Curt Trailer Connector Adapter - 4-Way Flat to 5-Way Flat - Vehicle End part number C57187 can be ordered online at etrailer.com or call 1-800-940-8924 for expert service.
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  • Reviews (87)
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  • Videos (2)
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CURT Trailer Wiring - C57187

  • Wiring Adapters
  • Single-Function Adapter
  • 5 Flat
  • Plug and Lead
  • 4 Flat
  • CURT

Convert your vehicle's 4-way flat trailer connector to a 5-way flat. Plug the 4-pole connector into your vehicle and connect the wire leads to get the electric brake function.


Features:

  • Adapter converts your 4-way flat trailer connector to a 5-way flat trailer connector
  • Additional wire leads for reverse lights
  • Durable molded plastic construction resists corrosion
  • Simple installation
    • Wiring harness plugs into existing 4-way flat connector and hardwires to existing wiring


Specs:

  • Wire configuration:
    • Green: right turn signal and brakes
    • Yellow: left turn signal and brakes
    • Brown: tail lights
    • Blue wire: reverse lights
    • White wire: ground wire
  • 1-Year limited warranty


57187 Curt Trailer Connector Adapter - 4 Way Flat to 5 Way Flat




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Video of Curt Trailer Connector Adapter - 4-Way Flat to 5-Way Flat - Vehicle End

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




Video Transcript for Curt 4-Way Flat to 5-Way Flat Trailer Connector Adapter Installation - 2010 Acura MDX

Today on our 2010 Acura MDX we're gonna be installing Curt's four way flat to five way flat trailer wiring adaptor. This adapter's gonna allow you to take your four pole wiring on your MDX, and convert it to five pole wiring. Five pole wiring is a lot less common than your four pole wiring, so you typically don't find kits out there that just install straight five pole wiring. But if you're trailer does have a five pole, and you need this simply plugs in. And to get those reverse lights working you can take blue wire and route it your reverse lamp circuits on your vehicle. It comes with wiring, and quick splice to get that connected.We'll begin our installation at the back of the vehicle with the lift gate open.

We'll need to connect the reverse lamp circuit wire. Now the one that comes with your kit isn't gonna be long enough to reach your connector, so we're gonna have to extend this. You can pick up additional wire here at etrailer.com. We'll access our reverse lamp circuit located behind the grommet here in the upper left behind our lift gate. You just wanna take that, and pull that back to reveal our wiring.And we want the small brown wire that's in here.

This is gonna be our reverse lamp circuit. Now that we've got our brown wire separated from the rest of wiring we'll slide the quick splice that comes with the kit over the brown wire. Just like that. We'll take our new wire, slide it into the other end of our quick splice there, and then use a pair of pliers or channel locks to crush the splice down into the wires. After you've got it crimped down just close your plastic in there, and we can reinstall our grommet.It's not a bad idea to maybe poke a hole in here, and you can feed that wire out through that hole.

So, we're just gonna take a small screw driver here. Try and stay towards the bottom. Poke a hole through it with our screwdriver then we'll take the other end of our wire and we're gonna poke that from the inside out through that hole. And you can further seal that up with a little bit of black silicone. If you need some silicone you can pick some up here at etrailer.com.We can then take our wiring, we're gonna route it down to our four pole connector where ever you have that mounted.

Our customer has his mounted outside the vehicle, so that's where we're gonna be routing it. If yours was inside the vehicle then you could simply come down and just wrap it around the weather stripping down here below. Once you get about that far I'm just gonna pull back the weather stripping, and we're just gonna follow the weather stripping down. Now if you're going outside we're gonna keep following that weather stripping down bringing our wiring along the way until we get about here where we can go down through the open seam underneath our weather stripping. And here you can just reach up behind the bumper, grab that wiring, and pull it down. Then you can just push the weather stripping back into place. If it does get up above your panel here you can kind of pop that up, get it tucked back under.Now we're under our vehicle. We've got our wire that we ran down. We can go ahead and trim off any excess that we've got there. Want to make sure we got some so we can connect it to our blue wire here, so we're just gonna trim that up about there. Now we'll take our blue wire, we're gonna strip it back. We'll take the wire that we ran down, we're gonna strip it back as well. And now we'll crimp the two together. Now you're kit doesn't come with any crimps. We're using a Heat Shrink Butt Connector for ours. And again our customer has his wiring routed outside the vehicle where typically on your MDX it's gonna be inside. If it was inside the vehicle you likely wouldn't need to extend the wire longer like we did. So, then we'll just crimp the other end on to our white wire, and then we can heat shrink it down.Now we can take the excess, we're gonna zip tie that to our four pole wiring. No zip ties come with your adaptor, but you can pick some up here at etrailer.com. Now everything's all connected, and all we need to do is plug our four pole end into our four pole flat on our vehicle, and plug our additional circuit in right there. And you're ready to now plug up to your five pole connector on your trailer, and hit the road.Now we can test everything out. You can either plug this into your trailer to test it out, or you can use a test light like the one I have here. So, we're gonna hook our ground up to the exposed terminal there coming out of our connector. I've got the hazard lights turned on as well as the headlights, and that'll be able to check all of our circuits except for the additional one that we ran which is for our reverse lights. You should have on your brown wire a taillight circuit that'll come up solid. Our yellow and green wires are our left and right turns signals, so they should be flashing with our hazards. These also double as your brakes. And lastly we have this one here, we'll have to put the vehicle in reverse in order to test that. So, you may need some extra assistance because you don't want to be back at the back of the vehicle when it's in reverse with nobody inside. And you can see our reverse lights are working properly.And that completes our installation of Curt's four way flat to five way flat trailer adaptor on our 2010 Acura MDX.

Customer Satisfaction Score:


Customer Reviews

Curt Trailer Connector Adapter - 4-Way Flat to 5-Way Flat - Vehicle End - C57187

Average Customer Rating:  4.8 out of 5 stars   (87 Customer Reviews)

Convert your vehicle's 4-way flat trailer connector to a 5-way flat. Plug the 4-pole connector into your vehicle and connect the wire leads to get the electric brake function.

by:

Used my 4-5 pin adapter to tow my 20 foot Mako to the ramp here in East Boothbay this past weekend. I am always pleased with the wide array of products etrailer stocks that help keep me on the road.



by:

I bought this product a year ago. My car was wired for a 4-prong utility trailer and last fall I purchased a small 5-prong motorcycle trailer that I intended to pull with my very small car. I needed this adapter to make everything work correctly on both units. It's perfect. The folks at e-Trailer are always super helpful and they pointed me to this one right away, knowing exactly what I needed (I had no clue - I'm a novice!) Once again, both the staff and the product came through for me 100%.

Pat

10/24/2022

Still 100 satisfied a year later. Great product and company customer service is commendable.



by:

I cannot give this item a fair rating as the trailer lights on my 2016 trailer do not work. The trailer is in absolute MINT condition so no problem there. I had the wiring checked on my 2011 Toyota Siena, everything there checked out A-OKAY, but when I attached the adapter to my Van/Trailer wiring, nothing, no lights. I talked with a gentleman from etrailer but he was of no help and not able to offer a possible solution. The wiring harness was installed on my Toyota three years ago for a different trailer that took a 4-way flat to a 4-way flat and worked flawlessly with that trailer.

Etrailer Expert

Mike L.

5/15/2018

Anytime theres a trailer wiring issue, the first step is to narrow down where the problem actually is. Use a circuit tester like # 40376 or a multimeter to test each pin on the trailer connector as a helper applies the brakes, uses the turn signals and turns on the headlights. This will confirm the functionality of the wiring harness on the vehicle. Next, plug in the # C51787 adapter. Test each pin on the adapter as its function is activated. If all checks out okay, youve ruled out the vehicle and the adapter as being the problem, which leaves the trailer. Weve seen wiring problems on brand-new trailers, so its entirely possible that the problem could exist on the trailer, regardless of its overall condition and appearance. To test the trailer lights independently of the tow vehicle, you an use a 12 volt battery. Ground the battery to the trailer frame, then apply power from the positive battery post to each pin on the connector and see if the lights for each circuit illuminate. Ill also link you to some Help articles about trailer wiring. One article will help you understand the basics of how a trailer wiring system works, the other helps with basic troubleshooting. https:www.etrailer.com/faq-wiring.aspx



by:

Quick install, highly recommend the ada pter.



by:

Great design and quality. Now I just need to figure out where to tap into the backup wiring on a 2021 Sienna so that I can use this to trigger the brake lockout solenoid on my trailer when backing up.

Barry B.

4/27/2022

Still works great after a year. And I did figure out how to connect to the backup wiring in the tailgate so my trailer brake lockout works too.



by:

My newly acquired boat trailer(previously owned) wiring hookup didn’t match my SUV wiring connection so I purchased this adapter. Working very well thank you.



by:

Delivered fast and efficiently. Thank y ou.



by:

EXCELLENT PRODUCT.. Re-wired my trailer with LED and reverse lights; not realizing, these lights come with an extra plug. The converter adapter was exactly what I needed. Tried to just splice the wires together...naw, bad idea! Use the adapter; it works.



by:

Works as intended. Easy to wire up. Just splice the blue wire into your vehicles reverse light wire and your good to go. Works great for my boat trailer with led brake & reverse lights



by:

Just what he said I needed
Will recommend
to all



by:

etrailer folks are terrific. When ever I call they have a solution for the situation at hand. In this case I needed an electrical connector to adapt my boat trailer to a new vehicle and Robert knew exactly the correct product to use. Courteous friendly help as usual.



by:

Installed on a 2017 Jeep Wrangler unlimited. Product arrived as stated. Easy to install took abou 10 minutes. I have pulled my boat several times lights work and the main reason was to dis-engage the surge brake when in reverse. Works great!!



by:

Really fast turn around time after ordering product. Thanks



by:

Just what I needed to get my surge brakes from engaging on uphill backups! The video for my 2019 Highlander helped immensly. Toughest part was wiring tot he reverse light circuit but once that's done no more surge brake "backup" headaches.



by:

Just what I needed to wire my new boat trailer to my truck.

Hugh H.

8/8/2021

Works perfectly. I like its tight fit for a great conection



by:

Second item that I ordered from etrailer.I was able to easily track it and it arrived quickly. Perfect fit from my new truck to my boat trailer. Thanks for the excellent service!



by:

Product as specified on eTrailer site to solve a particular problem between my car and a boat trailer. Excellent description and instructions.



by:

Arrived as ordered and in a very timely manner



by:

Excellent product. Exactly what I needed to hook up my five pole trailer to my four pole truck.

Leonard E.

5/9/2021

Still working as well as it did on day one. 5 star product.



by:

Solid product. Worked as advertised and very easy installation. And Will Call worked great...ordered and picked up in the same day:)



by:

Seems to be exactly what I needed for converting my four pole vehicle side to a 5 pole trailer side. The installation video was very helpful.



by:

Once I figured the right wire for the reverse lights, I had it all hooked up in 10 minutes. Easy Peasy, thanks for all the customer help when I called in.



by:

Products were exactly as described and work great. Had all the accessories I needed and showed up on time. Also came with detailed instructions on how to install! Will.use them again.



by:

Item delivered ahead of schedule and exactly as advertised. Adapter is a real problem solver. Assistance by sales staff was fast and professional.



by:

solved a wiring problem that has bothered me Perfect length of adapter Order was delivered faster that promised.


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Show More Reviews

See what our Experts say about this CURT Trailer Wiring

  • How To Hook Up a Trailer With 5-Way To a Vehicle With 4-Way
    In order to hook up a trailer with 5-way flat to a vehicle with 4-way flat you need to use the Curt Trailer Connector Adapter part # C57187. That blue wire will need to be spliced into the vehicle's reverse light circuit but there is no way around this as the trailer will require it. In order to find the circuit you'll have to do some testing with a circuit tester.
    view full answer...
  • How To Activate Surge Brake Reverse Solenoid On Vehicle with 4-Way Harness
    In order to activate the reverse solenoid on the brake actuator you will need to converter the 4-way trailer wiring harness you have to a 5-way using the Curt Trailer Connector Adapter part # C57187. This adapter will then plug into the 4-way on the vehicle and allow you to hook-up the 5-way on your trailer but you will need to run one wire from the adapter to the reverse light circuit on your vehicle. In order to find the correct reverse light circuit on your vehicle you will need to obtain...
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  • How Do I Run My Backup Lights from the Trailer into My Cab of My 2000 Peterbuilt?
    In order to run the backup light into the cab, all you need is the Curt Trailer Connector Adapter - 4-Way Flat to 5-Way Flat - Vehicle End # C57187. This harness will allow you to convert your 4-way harness to a 5-way with the additional backup light pin. If you currently have a 7-way installed, I recommend routing some spare wire from the reverse signal on your 2000 Peterbilt to the 7 way and then into the trailer's reverse lights.
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  • Recommended 4-Way Flat to 5-Way Flat Adapter for a Boat Trailer
    To connect to your boat trailer's 5-way connector you will need the Curt Trailer Connector Adapter item # C57187. This adapter plugs into the 4-way you have now on your truck and then gives you an additional wire you will run to the reverse light circuit of your vehicle. I have linked an installation video below to walk you through the process.
    view full answer...
  • Connecting Vehicle Side 4-Way to 5-Way on 2003 Boatmate Trailer
    Based on your description it sounds like your 2003 Boatmate trailer has hydraulic drum brakes with an electric lockout on the surge brake actuator. If you had electric brakes the trailer connector would likely be a 7-way, and a 5-way flat would not be able to power the brakes. You are correct though, the 5th function is for the reverse light circuit. When you put your vehicle in reverse this sends power to the lockout so the surge brakes do not activate and lock up in reverse. In order...
    view full answer...
  • How To Adapt Your 4-Pole Flat Trailer Connecter To A 5-Pole Flat Trailer Connector
    Yes, I recommend the Curt Trailer Connector Adapter # C57187. This adapter will connect to the 4-pole connector you have on the rear of your vehicle and includes an extra wire to run to the reverse light circuit on your vehicle. The reverse light wire will come with a bullet-connector so that you can remove the adapter as needed. I've attached a short video below where Dave will show you how to splice in the reverse light wire.
    view full answer...
  • Parts Needed to Add 5-Way Trailer Wiring Harness to Vehicle with 4-Way
    You'd just need a 4-way to 5-way adapter part # C57187 which will plug into your active 4-way and give you a wire you'd need to run to the reverse light circuit of your vehicle which would then be active whenever the vehicle is put in reverse.
    view full answer...
  • 4-Way to 5-Way Adapter for 2003 Chevy Express Van Towing Trailer with Surge Brakes
    What you need is a 4-way to 5-way adapter like with the Curt # C57187. This plugs into your 4-way and has a wire you'd run to your reverse light circuit and use the included quick splice to attach to. This will give you a functional 5-way like what your surge brake coupler needs.
    view full answer...
  • Recommended 4 way to 5 way adapter for 2014 Ford Explorer
    In order to use your 2014 Ford Explorer's 4 way with a trailer that has a 5 way connector you'll want to use the Curt Trailer Connector Adapter - 4-Way Flat to 5-Way Flat - Vehicle End # C57187. You'll just want to tap into the reverse light circuit on your vehicle, as you mentioned, to make the additional connection live for the trailer wiring. You can find the reverse light circuit by tapping into the wire of the reverse light on your tail lights.
    view full answer...
  • Availability of 5-Way Connector for 2022 Toyota Highlander With 4-way Installed
    What you need is the Curt Trailer Connector Adapter - 4-Way Flat to 5-Way Flat # C57187. This will connect to the existing 4-way on your 2022 Highlander and tap into your reverse lights to send power to the reverse lockout on your actuator.
    view full answer...
  • 4-Way To 5-Way Flat Connector Adapter
    You just need this adapter # C57187. The blue wire will tie into a wire on your 2017 Tacoma and then snap into the blue wire with the connection point. I have a video to help explain more!
    view full answer...
  • Can You Use A 4-Way Flat Trailer Connector With A 5-Way Flat Vehicle Connector
    You will not need an adapter to plug a 4-way Flat Trailer connector into the 5-way Flat Connector on your vehicle. You will just have one pin un-used on the vehicle side connector which is for the reverse lights. This is commonly needed for trailers with surge brakes. The only time you would need an adapter like the Curt Trailer Connector Adapter - 4-Way Flat to 5-Way Flat # C57187 is if the connectors were reversed and the trailer had the 5-way flat connector in which case an adapter...
    view full answer...
  • Is the Orange or Brown Wire the Hot Wire in My Back Up Light? And How to Find Out.
    The brown wire is usually your running lights but for all wires on your trailer you can apply a source of power from a 12V car battery to see what function each wire activates. You should connect the battery's negative terminal to the trailer frame and then apply 12V power to each wire to see what each wire connects to. This should help you to identify which wire does what on that tail light. I attached a FAQ on trailer wiring for you to check out also. You can refer to it for trailer...
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  • Availability of 4-Way to 5-Way Adapter for 2008 Lincoln Navigator Towing a Boat Trailer
    In order to add a 5-way connection to your 2008 Lincoln Navigator you need the Curt Trailer Connector Adapter - 4-Way Flat to 5-Way Flat - Vehicle End # C57187. You will plug the adapter into your existing 4-way connection and the additional wire will connect to your reverse lights to send the signal for your electric lockout. I have attached an installation video for your reference.
    view full answer...
  • Where Does Blue Wire of 4-Way to 5-Way Adapter Need to Run
    Yes, if you connect the blue wire of the Curt trailer wiring 4-way to 5-way part # C57187 to the reverse lights of your tow vehicle it will activate the reverse lockout solenoid of your trailer wiring and will allow it to be reversed without applying the brakes.
    view full answer...
  • What Does The Fifth Wire Do On A Boat Trailer 5-Way Wire Harness Connector
    The fifth wire on your trailer's wire harness is for your reverse light signal, like you thought. It can get wired to both the reverse lights and an electrical lock out on your surge brake coupler. This makes it so that you don't have to get out of the tow vehicle and walk back to the trailer to manually lock out the brakes so that you can back the trailer into the water. It's really just for convenience so you don't have to use it if you don't want to. If you do want this function and...
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  • Recommend Adapter To Change 4-Way Trailer Connector To 5-Way On 2019 Ford Ranger
    The most common connectors on boat trailers are the 4-way and 5-way flat connectors. The 5-way flat connector is easy to identify as it looks just like the 4-way connector but will have one extra pin. If your trailer has a 5-Way flat connector you will need the Curt Trailer Connector Adapter # C57187 which will plug into the existing 4-way connector on your 2019 Ford Ranger and will require you to run the blue wire up to your reverse light wire for use with surge brakes. If you do not...
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  • Correct Trailer Connector for Boat Trailer with Surge Brakes and Electric Lockout
    In most cases, boat trailers with surge brakes and an electric lockout solenoid use a 5-way flat trailer connector. In which case, you will need to install the Curt Trailer Connector Adapter part # C57187 and that's it. This will plug into the 4-way and then splice into the reverse light circuit.
    view full answer...
  • 4-Way to 5-Way Adapter for 2019 Toyota Highlander Towing Boat Trailer
    To convert the 4-way of your 2019 Toyota Highlander to a 5-way requires the 4-way to 5-way adapter part # C57187. This plugs into the 4-way you have now and then gives you an additional wire you'd run to the reverse light circuit of your vehicle. To prevent wires from being visible would require you to route the wire behind interior panels on it's way to the reverse light wiring.
    view full answer...
  • Recommended 5-Way Adapter for a 2017 Honda Pilot
    You don't need a new harness. All you need to add a 5-way to your 2017 Honda Pilot is the Curt Trailer Connector Adapter item # C57187. You will plug the adapter into the existing 4-Way on your Pilot. Then the blue wire will get spliced into the reverse circuit wire on your Honda for the reverse lockout on the boat trailer to function. I have linked a installation video we did below so you can see the steps on how to get the adapter set up. This video isn't on a Pilot but the part is universal...
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  • How To Install 5-Way Trailer Connector On 2011 Toyota Sienna
    In order to install a 5-way on a 2011 Toyota Sienna you'll need a plug-in 4-way and 4 to 5-way adapter as there are no plug-in 5-ways for this vehicle. I recommend the T-One Vehicle Wiring Harness part # 118498 with the Curt Trailer Connector Adapter part # C57187. The adapter will require one wire to be spliced into.
    view full answer...
  • Best Way To Add A 5-Way Flat Trailer Connection To My Mototcycle.
    I have a solution for you. However you can use the 4-Pole Hardwire Kit with Circuit Tester # 18252 to add a 4-way flat to your motorcycle. Then using the Curt Trailer Connector Adapter - 4-Way Flat to 5-Way Flat - Vehicle End # C57187 we can convert it into the 5-way flat that you need. There is not a custom fit wire harness for motorcycles. So you will need the circuit tester to find the correct wires to connect to the universal wire harness. To help I have linked a help article on...
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    Image 1 for
  • Recommended 5-Way Wiring Harness for a 2023 Chevy Express Van
    We have the two parts you'll need to add a 5-flat to your 2023 Chevy Express van but like the 7-way, they don't make just one that will add a 5-way to your vehicle. The first connector you will need is the Curt Wiring Harness item # 55540. This custom fit connector plugs into existing wiring in your rear cargo area which is located behind the interior trim panels in your rear cargo area. This will provide you with a 4-flat connector. The second part you'll need is the Curt Trailer Connector...
    view full answer...


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Info for this part was:

Employee Lindsey S
Edited by:
Lindsey S
Employee Jameson C
Expert Research:
Jameson C
Employee Adam R
Expert Research:
Adam R
Employee Jacob T
Video Edited:
Jacob T
Employee Dustin K
Video by:
Dustin K
Employee Cole B
Installed by:
Cole B
Employee Wilson B
Updated by:
Wilson B
Employee Kristina F
Updated by:
Kristina F
Employee Isabelle B
Updated by:
Isabelle B
Employee Amanda M
Written by:
Amanda M
Employee David F
Test Fit:
David F

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