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Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector

Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector

Item # 30717
Our Price: $35.91
Trailer Wiring
Shipping Weight: 0.57 lbs
30717 - 4 Flat Tow Ready Wiring Adapters
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Great Prices for the best trailer wiring from Tow Ready. Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector part number 30717 can be ordered online at or call 1-800-940-8924 for expert service.
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  • Reviews (585)
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Tow Ready Trailer Wiring - 30717

  • Wiring Adapters
  • Single-Function Adapter
  • 7 Round - Blade
  • Plug and Lead
  • 0 - 5 Feet Long
  • 4 Flat
  • Tow Ready

  • Adapter converts from 4 pole wiring on vehicle to 7 pole round plug
  • Additional wire leads for brake, power and accessory are 12" long
  • Mounting bracket (18138) is sold separately

Wiring diagram

Product detail

20321 Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector

California residents: click here

Video of Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector

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

Video Transcript for Tow Ready Wiring - Wiring Adapters - 30717 Review

Customer Satisfaction Score:

Customer Reviews

Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector - 30717

Average Customer Rating:  4.8 out of 5 stars   (585 Customer Reviews)


i had to replace these two items as my dear daughter went down our goat path driveway too fast. they replaced the originals from etrailer from the prior year. shipping is timely and customer service actually helps! i wired from battery to controller to hitch myself, and everything fit.

its working well, no issues.
Bruce - 03/23/2023


This product works as expected. There is not too much to the installation, just plug it in properly and mount the ground wire.
I did not find an easy way to mount this to my wife's Odyssey, or to the trailer hitch (item# 75270). Luckily, I do prototype design and manufacturing. So I came up with my own solution. I designed and made my own bracket to mount the 7 pole to the trailer hitch. It works like a charm, and looks great!


Joe at etrailer was able to provide this solution and saved me literally hundreds of dollars to have a reputable place put in a new harness onto my AWD MKX. Thank you!

The adapter worked out perfectly. And now after almost a year no issues whatsoever.
James - 01/23/2023


The staff is very friendly. I would have awarded 5 stars but there was a shipping issue. They did get me all the parts I ordered, with simple communication, a couple pictures and minimal frustrations I got everything over two shipments. It took a little longer to get everything then anticipated. They deserve 4.5 stars not just a 4. I will do business with them again and I do recommend them. Will be ordering a receiver hitch through them this spring.


I was really skeptical about this adapter but for no reason! Installed in about 10 minutes using etrailer mounting bracket, dielectric grease, a couple zip ties, and some electric tape. Worked perfectly the first time I tested it on my trailer.


Wiring harnesses will simplify the job I'm doing glad that I found these products and I also had a good experience dealing with etrailer they keep you informed about shipping and the products are ship fast. Thank you


Works great! Remember to ground it to: 1) tow vehicle frame, or 2) directly to tow vehicle negative terminal. Do not ground it trailer frame because you need to complete the circuit to the tow vehicle battery.


this connector along with the short L bracket and the mount bracket- gave me a nice connector to my hitch.
Though I used the short connector and did have to slightly bend it to allow the 4 to 7 pole connector to fit.

If Id bought the long L bracket-- It could have worked-- but bending a little worked well.


Works great. Easy install.

more sensitive to dirt than I expected, but that might be common to all trailer connections, I don't know. I noticed on a trip that my brake controller said NC (no connection), and I didn't have trailer brakes, which meant my blinkers probably hadn't been working, either. I got pretty worried, and looked at it and only saw just a little black gunk on one blade. But cleaning that small amount of black gunk off solved the problem.

So far, so good!

Thanks for your business and your review, Zach! Using dielectric grease like 11755 on your connections increases reliability and the life of the connection by preventing corrosion and sealing the connection.
-- Etrailer Expert Laura E - 02/10/2017


Works great to get the 7 pole connection that I needed for my trailer.


This 7 point harness wired right in with my T1 connector and is great for hooking up to my camper, very easy to install!


Super Service at ETrailer - I have never had an issue with the help provided or with any product

Was easy to install. Fit perfect. Has stayed looking great. It is great having a mounting bracket for the electrical hookups. It keeps the 7pin more out of the way and more solid.
Paul - 10/05/2022


Every phone encounter I’ve had with etrailer has been excellent. Their staff on the phones know their stuff and they have most every rv/trailer accessory known to man. The seven pole side is much more robust than the four pole side, which I leave connected all of the time. Problem solved


There was no splicing wires, it was plug-and-play, highly recommended, very easy installation


Every time etrailer has provided me with the needed wiring!


I wanted to show the custom installation. I did not want it under the bumper


I really appreciate you following up on my order. The information and videos will help when I drop the harness and circuit breaker off at my local shop. When I went to them originally with my problem I couldn't answer all their questions. With the parts in hand they should be able to convert my four prong to the seven prong plug used on my new trailer. Thanks also to Craig at CampInn for directing me to your site and the parts they are using in the construction of my trailer.


I bought this because I hated the flat four pole that just hung over the bumper. Drilled a 1 7/8 inch hole in my bumper with bimetal hole saw. Mounted nice and clean. Be sure to hook up the White ground wire to your frame. The ground wire from the flat four does not pass thru this connector. Also if need be you can still pull a trailer with a flat four pole just by unpluging it

It’s a year later. Still working great no problems
Carl m - 01/13/2019


Has been working great since purchased and installed 3 months ago. Used for several different trailers and long distance trips. Easy to install. Had to be slightly creative with the attachment of the ground. Did not see a reason to have a ground on this portion since everything else is already grounded, however would not work without grounding to the frame. Only used the four way connection and taped remaining three back. Hope for good things to come with this produce. Highly recommend this product.

Had the same issue with the ground kurt. Almost gave up on it until I read your post. Thanks.
-- comment by: mike g - 06/17/2014
Thank you so much. Ours wasnt working either until we grounded it to car frame.
-- comment by: Sarah - 10/08/2015


Hitch was as advertised. The printed instructions made it a breeze. Took about an hour with me and an experienced mechanic. The light kit took a little longer than expected but was installed inside the car vice behind the lights like the video showed. Towing a camper this weekend, not expecting any issues.

All is well. Don’t use it that often but when I needed it they’ve been there. I’ll use etrailer from now on.
B K - 08/10/2018


This is a great product . The price was $18.00 dollars cheaper than some I found online. I have a 2002 dodge ram 1500 pickup, this adapter will change the 4 pole( which is made on my truck) to a 7 pole( which is on the trailer I will be using). The product connected, and bolted up to my truck bumper very easy. E trailer is the best.

Im still enjoying this product, Ive used it several times, still workingwell
Rics49 - 04/06/2015


Great product makes wiring a 4 flat to a 7 rv blade a snap. However the ground in the 4 flat is not connected. Must connect extenal grd.Not a big deal. One nice thing is shipping is resonable!!

Outstanding, no issues with corrosion on plug
Harold D - 10/22/2017


works great! easy install.


Nice harness


Pretty straightforward and works great.

Show More Reviews

See what our Experts say about this Tow Ready Trailer Wiring

  • Wiring Adapter to Mate 4-Pole Vehicle Connector to 7-Way on Tent Trailer
    You can use TowReady 4 Pole to 7 Pole Vehicle End Trailer Connector # 30717 to adapt your Grand Caravan's 4-pole trailer harness for the 7-way blade style connector on your pop-up trailer with surge brakes. You will simply plug in the vehicle's 4-pole to the adapter's connector; the pigtail leads on the adapter will not require connection for use with your surge brake-equipped trailer.
    view full answer...
  • Troubleshooting Trailer Lights That Flash with Blinkers and Don't work When Brakes are Applied
    First thing I would do is check for corrosion in the 7-way of your 2004 Chevy Avalanche and clean as necessary. Most of the time this fixes situations like this. Aside from that the other most common problem is bad grounds on the trailer lights. You will want to make sure the grounds on the trailer light assemblies are connected to a clean metal surface. Also, the ground strap that runs from the trailer 4-way to the trailer frame needs to be connected to a clean metal surface. Aside from...
    view full answer...
  • Can 4 to 7-Way Trailer Connector Adapter Be Grounded to Trailer Frame Instead of Vehicle Frame
    Since the 4 to 7-Way adapter # 30717 is a vehicle side connector it will be mounted on the vehicle. Grounding it to the trailer frame would mean you would have to disconnect that ground every time you disconnected the trailer from the tow vehicle. The trailer side connector already has a main ground connection so this one needs to stay grounded to the vehicle side.
    view full answer...
  • Right Turn Signal Not Working on 7-Way After Installing 4 to 7-Way Adapter # 30717
    Since the brake lights and turn signals are combined on the same circuit, one for each side (3 oclock and 9 oclock pins) the right turn signal not working on the 7-Way is a little strange but not without precedent. It is likely a ground issue. Make sure that the white ground wire on adapter # 30717 is attached to a clean and corrosion free bare metal surface. Also, make sure the vehicle side 4-Way is clean and free of corrosion as well. Since the turn signal functions on the 4-Way it...
    view full answer...
  • How and Where to Wire the Four Loose Wires on the 4 Pole to 7 Pole Adapter, part # 30717
    The white wire is a ground and should be attached to the frame. The blue wire goes up to the blue wire on the brake controller. The black wire is a 12 volt power wire and is connected to the car battery. The orange or yellow wire can serve a few functions. It can be a reverse lockout for hydraulic brakes, it can be an auxiliary power supply, it can be used for reverse lights on a trailer, or if not needed, it can be taped out of the way. I attached an FAQ page on brake controller wiring...
    view full answer...
  • Where Do the Black and Blue Wires on 30717 Attach To on a 1999 Ford F-250
    If your truck has the brake controller port underneath the dash, then there will be some wiring towards the rear of the truck that you will need to splice into. The blue wire on part # 30717 needs to be spliced into the blue wire on the factory tow wiring. We have an instructional page that shows how this is done that I have linked to below. You can also splice the black wire on the 30717 into the orange wire on the truck for a 12V power source.
    view full answer...
  • Where Does the Black Wire Attach for Harness 30717 on a 2003 Chrysler Town and Country
    The black 12 volt lead on Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector, # 30717, attaches directly to the battery on your 2003 Chrysler Town and Country. You will have to attach the black wire to a length of additional wire, like 10 Gauge Blue Primary Wire - per foot, # 10-1-1, under your vehicle and run that wire to the battery through a 40 amp circuit breaker, # PK54540.
    view full answer...
  • What is the Yellow Auxiliary Wire for on 4 pole to 7 Pole Adapter from Tow Ready Part 30717
    The black wire is the 12V hot power source that is usually used to maintain a trailer battery. The yellow wire, in some cases it is orange or purple, is for the center post which is usually wired for reverse lights or a reverse lockout on a boat trailer. If you do not need a reverse circuit, you can just tape the yellow wire up and out of the way.
    view full answer...
  • Where to Connect Blue Wire on 4-Pole to 7-Way Adapter Part # 30717 if Trailer Has No Electric Brakes
    If the trailer you are planning on towing does not have electric brakes, you can simply leave the blue wire on the 4-pole to 7-way Adapter, part # 30717 disconnected. You can bundle it up, and zip tie it up out of the way. If the trailer does have electric brakes, a brake controller would be needed to actuate them. The blue wire would be extended and ran under the vehicle to the engine compartment, and through the firewall to connect with the blue brake output wire on the brake controller. To...
    view full answer...
  • Can a Adapter 4 Pole to 7 Pole Be Used Just for Tail Light Functions
    Yes, you could use this Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector # 30717 to adapt from a 4-way to a 7-way. You could simply tie they wires you would not use up and out of the way and you would be fine. You will still need to ground the white wire though. I attached an installation video for this product for you to check out also as well as an FAQ on trailer wiring for you to check out.
    view full answer...
  • Trailer Lights are Not Working with 4-Way to 7-Way Adapter Plugged Into 2011 Ford Escape
    For the adapter # 30717 to function, the white wire has to be grounded to the vehicle frame. Without that ground it will not function. If it is properly grounded and you still do not have lights on the trailer, make sure that the adapter 7-Way and the trailer 7-Way pin configurations match up. I have included a link to our wiring FAQ article that shows diagrams of how various connectors should be pinned. If you are still not getting lights test the 4-Way on the vehicle with a circuit...
    view full answer...
  • What are the Functions of a 4-Way Trailer Connector
    Trailers use a combined brake and tail light circuit (2-wire system). The left brake light and turn signal is with the yellow wire and the right brake light and turn signal is with the green wire. I have included a link to our FAQ on wiring for you that shows the functions.
    view full answer...
  • Left Turn and Brake Signal Does Not Work Using the Adapter 4 Pole and 7 Pole Connector # 30717
    The first thing that you will want to do is to use a circuit tester like Quickee Circuit Tester, # 3808, to test the pins for proper function at the 7-way connector, # 30717, that you just installed. I would recommend testing each pin for proper function. When looking at the 7-way connector, the drivers side brake and turn signal, or brake and left turn signal, pin should be the pin in the 9 o clock position. If all of the pins on the 7-way connector function appropriately, then you know...
    view full answer...
  • Dim and Malfunctioning Trailer Lights on a Trailer Towed by a 1988 Chevy C/K Series Truck
    This sounds like a weak ground, corroded connector, or both. Make sure that the ground on the 7-Way you installed is attached to a clean and corrosion free bare metal surface. A weak ground could cause this issue. Ground problems normally show up when there is more load on the system like when the running lights are on and you step on the brake. Also make sure the 4-way that you installed is properly grounded. A corroded connector can cause all sorts of weird things to occur as well so...
    view full answer...
  • Finding a Ground Location for a Trailer Wiring Harness on a Kia Optima
    You may need to scrape away some undercoating on the bottom of the vehicle in order to get a bare metal surface. Any surface with coating or paint will need to have those materials removed in order to get a good ground connection. Usually behind a tail light assembly there is some bare metal. You can also look for other wiring harnesses nearby and ground it in the same location.
    view full answer...
  • Troubleshooting a 2006 Chevy Silverado 12 Volt Trailer Connector Circuit
    It sounds like the 12 volt circuit has not been completed under the hood of your 2006 Chevy Silverado. Check out the FAQ article I attached that shows where this connection is made so that you can check there. You may find that the connection is made but the fuse is blown, so check and replace that as necessary.
    view full answer...
  • Testing Wires On a 1994 Jeep Grand Cherokee to Determine Functions to Install a Trailer Connector
    You cannot go by color because there is no standard for colors. You have to go by function only. To do this you will use a circuit tester like # 3808 and test the vehicle wires one at a time while someone sits in the vehicle and runs through all of the light functions. Then you can wire it all up following the functions (not colors) in the diagrams in the FAQ I have linked. On the trailer side, I assume the connector is fine. If the trailer is new then white is likely ground, brown is...
    view full answer...
  • Troubleshooting Left Brake Light Not Functioning on a Trailer Towed by a 2002 Town and Country LX
    I would suspect you are having a ground issue. Ground issues usually come out when the brake lights are being applied because both tail lights are drawing the most amperage at that point. I would check your trailer connector for corrosion and clean as necessary-as the problem is usually there or where the tail light assembly grounds. If the tail light assembly grounds through the installation hardware you will want to be sure they are installed on a clean metal surface. I attached an...
    view full answer...
  • Will Running the 12 volt Accessory Wire from a 7-way to a Trailer Battery Overcharge it
    The battery charging method that you described would not overcharge the battery of your trailer at all. Actually, at most it will put a very light maintenance charge on the battery to keep it topped off, but would not recharge the battery if it was fully discharged.
    view full answer...
  • How to Determine the Amperage on the 12 Volt Power Circuit in a Trailer Connector
    The amperage on the 12 volt power circuit will depend on the amperage draw of the item receiving the power on the trailer. When aftermarket 7-way trailer connectors are installed on vehicles, it is recommended to have a 40-amp circuit breaker inline on the power wire going from the trailer connector to the battery. If your truck has factory trailer wiring, there will be a fuse in the fuse box designated for that circuit. You can check your owners manual to see the names and locations of...
    view full answer...
  • 7-Way Wire Color Functions for Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector, # 30717
    You are correct. The white wire is grounded to the frame, the black wire runs to the battery, and the blue wire is run to your trailer brake controller. The yellow wire is an auxiliary wire, and can be used for whatever extra purpose you need it for. If you have reverse lights on your trailer or hydraulic surge brakes with reverse lockout, you can splice the yellow wire into your vehicle reverse lights or to the lockout. I have posted links to our wiring help pages for you to review.
    view full answer...
  • 4 Pole to 7 Pole Vehicle End Trailer Connector 30717 Yellow Wire
    The yellow wire on the Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector, part # 30717 can be used as an auxiliary wire. Some people will use it to light the reverse lights on their trailer, as a reverse lockout circuit or maybe to power a break-away kit. If you do not have a need for the additional source, the wire can be grounded with your ground wire.
    view full answer...
  • 4-Way to 7-Way Wiring Adapter
    I would recommend the 4-way to 7-way Adapter, part # 30717. Keep in mind that although you will have lighting functions, the electric trailer brakes will not work unless the lead on the adapter for the brake output is installed to a brake controller.
    view full answer...
  • Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector Instructions
    Sorry about that, I'll be happy to help! When connecting the adapter, (4 Pole to 7 Pole Vehicle End Trailer Connector), the white wire is your ground wire, the black is the hot wire to the 12V, the blue wire is to the electric brakes, and the yellow wire is for reverse. The 4 pole just plugs into the existing 4 pole.
    view full answer...

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