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Trailer Wiring 7-Way Upgrade Kit

Trailer Wiring 7-Way Upgrade Kit

Item # ET7WK
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ET7WK - Junction Box etrailer Wiring
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This kit contains everything you need to upgrade from a 4-way, 5-way, or 6-way connector to a 7-way connector. Includes 7-way RV-style trailer connector, junction box, wire loom, and hardware. Call 800-298-8924 to order etrailer accessories and parts part number ET7WK or order online at etrailer.com. Free expert support on all etrailer products. Guaranteed Lowest Price and Fastest Shipping for Trailer Wiring 7-Way Upgrade Kit. Accessories and Parts reviews from real customers.
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etrailer Accessories and Parts - ET7WK

  • Wiring
  • Junction Box
  • etrailer

This kit contains everything you need to upgrade from a 4-way, 5-way, or 6-way connector to a 7-way connector. Includes 7-way RV-style trailer connector, junction box, wire loom, and hardware.


  • Kit allows you to upgrade from a 4-way, 5-way, or 6-way connector to a 7-way connector
    • Provides additional circuit for brakes, battery, or reverse lights
  • Heavy-duty, 7-way, RV-style trailer connector is insulated and molded to protect terminals and wires
  • Weatherproof, corrosion-resistant 7-pole junction box protects wires, eases installation, and makes diagnostics simple
    • Ring terminals allow for easy connections
  • Wire loom protects wiring from the elements and allows wires in and out along any point of the loom for easy installation
  • Includes:
    • (1) 7-Way trailer connector
    • 1 Wiring junction box with mounting hardware
    • 8 Ring terminals for 12- to 10-gauge wire
    • 8 Ring terminals for 16- to 14-gauge wire
    • 10' Wire loom
    • 1 Self-tapping ground screw


  • Junction box dimensions: 7" long x 3-1/2" wide x 2-1/4" tall
  • Trailer connector length: 8'
  • Trailer connector wire gauges:
    • Black/white: 10 gauge
    • Blue: 12 gauge
    • Brown/red/green/yellow: 14 gauge
  • Wire loom dimensions: 10' long x 1/2" diameter
  • Ground screw: #8 x 1/2" long

Wiring Code
Molded Connector Function Usual Trailer Wire
White Wire Ground White Wire
Red Wire Left Turn and Brake Yellow Wire
Brown Wire Right Turn and Brake Green Wire
Green Wire Tail Lights Brown Wire
Blue Wire Brake Power Blue Wire
Black Wire 12 Volt (hot lead) Black Wire
Yellow Wire Auxiliary -

ET7WK Trailer Wiring 7-Way Upgrade Kit

Video of Trailer Wiring 7-Way Upgrade Kit

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

Video Transcript for etrailer 7 Way Trailer Wiring Upgrade Kit Installation

Today we're going to show you how to install part number ET7WK. This is a 7-way trailer wiring upgrade kit. This is going to be great for taking care of from the vehicle to your junction box whether you're rewiring a trailer or just upgrading existing wiring. The first thing we want to do is just kind of roughly route the new 7-way into the area we intend to mount our junction box. I'm going to be doing mine right back here behind the A frame around the corner, kind of centrally located here in the middle of the trailer. What we're going to do is use a couple of self-tapping screws, get this mounted in location. I'll take off the long screws here in the front cover.

That'll expose all of our studs. What we'll do is pull out, see one of these plugs here, kind of have a softer center to it. I'll make a little slit in there. We want to pass our 7 pole wire directly through that, slide it on up the wire a little bit there. I'm going to slide that back in. We'll find out retainer.

We want to replace that right over our 7 pole and then get it threaded in there. We'll use that keeper to compress our 7 pole wire, holding it nice and securely. We'll start dividing our wires into the areas they're going to be connected to. Our white's going to be for our ground. Our black is going to be for 12 volt power. For my left side, turn signal and brake light we'll be using our red wire.

The blue wire, that's going to be for our stop signal. The brown wire, that's going to be used for our right side turning brake. Our green wire's for our taillights. Our yellow wire, we're going to run that down here. That's going to be auxiliary.

You'd use that for reverse lights if you we're going to do it on a marine application. On our trailer application here, we don't have this. We'll disconnected it so it has a home in case we ever need to add it. We can start trimming our wires back. We'll start adding on our ring terminals. At this point all we have to do is make our connections from our trailer wiring. You definitely want to start this project with healthy, working trailer wiring. We've got our caps. Just like before, make a small slit or small puncture in it. The wire's in. Now left side turn signal's going to be our yellow wire. We're going to connect that short red wire there. We'll put on a serrated washer. They also supply us the nuts we need. The next one is going to be our brown wire here. This one is our running lights. You can see it's kind of brown and yellow, kind of both. That needs to connect to our green wire. Remember that was our taillight circuit. We're going to leave that one open because we also need to pick up the other side. Auxiliary wire we can go ahead and put a nut on that one. We're not going to be reusing it. Take our other one. This one we're going to pass through out brake power and ground. We'll pass through our right blinker and taillight. I'm also going to pass through an additional wire. This is what we're going to use for our ground. Let's get all of our wires separated here. We'll put on another keeper just to hold those wires in place for us. Let's strip back our 2 white wires. These are going to be our ground wires. They'll go to the ground stud. Let's place on one of our locking washers and a nut there. We need to get our brown coming from our other side. That's going to go on the same taillight stud as we put the other one. Running lights stud . Our brown wire, that's for our right side turn signal. That's where our green wire needs to go. That's going to take care of both the turn signals and the brake lights. Finally we've got the 12 volt power lead coming from our brakes. We want to get that connected to our brake circuit. That pretty much is going to take care of everything that we need to do to operate the lights on our trailer and also the brakes on our trailer. Get everything neat and tidy. We can grab our cover and place that back on. We just need to get our ground wire, ground it out. We've got a stud right there that we'll use. We've got a ring terminal on there. We can just ground it right back out. There will be a stud provided with the kit. If you don't already have a stud located like this one, you can just use that to get it secured up. Let's check it out, make sure everything's working the way it should be. We've got everything hooked up. Let's run through our test. First we'll turn on our running lights and make sure that we've got lights where we want them. We'll turn on the left brake and blinker signal. Working fine there, now the right. Working fine there. We can spin the tire, engage the brakes and we want to see it lock up just like that. With everything working as it should, that completes our installation of part number ET7WK, the 7-way trailer wiring upgrade kit.

Customer Reviews

Trailer Wiring 7-Way Upgrade Kit - ET7WK

Average Customer Rating:  4.3 out of 5 stars   (22 Customer Reviews)

This kit contains everything you need to upgrade from a 4-way, 5-way, or 6-way connector to a 7-way connector. Includes 7-way RV-style trailer connector, junction box, wire loom, and hardware.


Easier said than done 557048


Good heavy duty cable. Didn't really care for the over-molded plug. The pull tangs are soft and make it difficult to pull from the receptacle. Junction box is very sturdy and has plenty of room for routing wires. 487302


Used this kit to upgrade the wiring on my utility trailer. The junction box is suitably rugged. I mounted it on the underside of my trailer bed near the tongue. This box easily allows me to wire up a battery to on my trailer for a winch or breakaway brakes and keep that battery charged via the vehicle. 575712


Three connection wires from truck (2017 GMC truck) did not match up with color connectors indicated in junction box. Perhaps GM is different than most? 514344

Because trailer wiring color codes arent always consistent, its recommended to wire by function, not by wire color. Plug the wiring harness into the vehicle, and use a circuit tester like # 40376
Circuit Tester Kit
as each lighting function is tested, then wire accordingly. For more helpful information about trailer wiring, click on the provided link.
-- Mike L - 05/31/2018





The weather tight box works great. The wire color from the 7 pin connector does not align with function of the trailer and the labels in the box. I had to remove the 7 pin connector for now and install a flat 4, it now works. I will have to check each colored wire when plugged into the vehicle to figure out what each wires does. Other than a color coding issue it works great. 720910


Excellent quality product, install was a little challenging when it came to the 7 spade cable wiring, when did LT yellow wire become red and yellow auxiliary. You need to include a simple diagram of the junction box and where the connections go. Other than wasting a few hours figuring out what was going on, it all went well. Thanks 674667

There is more than one accepted wire color code for trailer wiring. This is why we provide a wire color/function chart in the product description above.
-- Mike L - 07/26/2019



Hi quatily product. Professional Company Prompt delivery 663830


Can't wait to put these on! 644043


all is well everything working as should be thanks for the great service. 616686


worked great just wish they came a longer in length with this kit had to add 10' of 7 pin wire to it to reach junction box 605973


Got what I ordered , It all fit ,worked well. 522969


works as expected 521933


Good quality kit installed quick and ea sy. 513576


Great product,Great service and fast sh ipping. 468320


Thanks for fast delivery and great service. The videos were great to repair my Atwood coupler. I will be using you guys again soon. 456659


Great product. Came with everything I needed. Makes a great test point and junction box. Highly recommend! 455865


Little disappointed with this wiring kit. The plug colors did not match up correctly for standard wiring. I ended up having to pin it all out with an ohm meter and connector on the truck (Ford F-150) and then match it to the trailer. Would have been nice for this to use standard colors and it would have saved me 30min. 442691


I am very happy with the items I received, everything went together with ease. This was the first time I attempted installing brakes on a trailer, your videos made it very easy to choose the items I needed and assembling. I will recommend etrailer to my friends in the future. Thank you John C. 423007


I am very happy with the items I received, everything went together with ease. This was the first time I attempted installing brakes on a trailer, your videos made it very easy to choose the items I needed and assembling. I will recommend etrailer to my friends in the future. Thank you John C. 423006


Great service 369461


I just received my order, the order came very quickly and completely. Everything looks good. I ordered the Etrailer brand. The quality seems very good. 324513


Ask the Experts about this etrailer Accessories and Parts

  • Does the Brake Output Wire Get Attached to a 12 Volt Trailer Battery
    In order to rewire your trailer, I strongly recommend you use the Trailer Wiring 7-Way Upgrade Kit part # ET7WK with the Bonded 4 Wire part # 16-4B-1. This is going to ensure you have all the correct wire gauge and the junction box makes for a clean install as well as an easy way to troubleshoot if you ever have issues. In regards to the brake output wire part # 10-1-1, this will receive power from the tow vehicle's brake controller via the 7-way, not a battery during normal braking. However,...
    view full answer...
  • Parts Needed to Rewire Trailer with 7-Way and New Wiring
    We offer handy junction box kits like # ET7WK that let you install a new 7-way plug and make the connections for each circuit on the trailer. You will need ring terminals like # 44-5310A to make the connections in the junction box; use butt connectors like # DW05745-10 to splice in any new brake wiring like part # 10-2-1. This is double bonded 10 gauge wire that you can use for power and ground for the brake assemblies. Or if you planned on grounding the assemblies to the trailer frame...
    view full answer...
  • 7-Way Wiring/Junction Box Kit Recommendation for Flat Bed Trailer
    The Trailer Wiring 7-Way Upgrade Kit # ET7WK that you referenced will cover all of the wiring from the trailer 7-way connector to a junction box for you to install on the trailer frame. Beyond that it would be a matter of running wires from the junction box to each of the functions you have on the trailer such as lights and brakes. We have 10 gauge wire like part # 10-1-1 (sold by the foot) for wiring up the brakes and then 12 gauge like part # 12-1-1 for the lights as well. I attached...
    view full answer...
  • Recommended Junction Box Installation For LED Lighting And Break Away Kit
    I'm happy to help. You can use the Trailer Wiring 7-Way Upgrade Kit # ET7WK to connect your trailer lighting. You can use the attached diagram to help you with color and function on the trailer side. I recommend using the 12 Gauge Black Primary Wire - per foot # 12-1-1. You can use ring terminals # DW05705-1 and butt connectors like # DW05745-10. You can use 16 gauge wire like # 16-4B-1 along with ring terminals # DW05737-1 and butt connectors # DW05744-5. Your side markers should...
    view full answer...
  • What Size are the Wire Studs in the Junction Box Included with Trailer Wiring 7-Way Upgrade Kit
    I went out to the warehouse to measure the studs on the junction box that comes with Trailer Wiring 7-Way Upgrade Kit # ET7WK. The studs are 3/16 inch. The kit does also include the appropriate size nuts as well as 3/16 and 1/4 ring terminals. I have linked a video showing an example installation for you.
    view full answer...
  • How to Wire a Car Dolly for Electric Brakes
    If you will be adding electric drum brakes to your car dolly then you will need to install a 7-way trailer connector. For this, I recommend using the Trailer Wiring 7-Way Upgrade Kit part # ET7WK. I have attached a photo which displays how the wires will need to be ran on the trailer connector. In addition to the new trailer wiring harness you will also need braking assemblies, hubs/drums, a breakaway kit, and a brake controller. If you would like for me to recommend any of these parts...
    view full answer...
  • How To Wire Trickle Charge For Battery On A Camper Trailer
    To begin, you would need to install a 7-Way connector on the trailer. Since you will need several things including connectors, I recommend going with the Trailer Wiring 7-Way Upgrade Kit, Item # ET7WK, to make your project easier. It has a 7-Way connector, junction box, wire loom, and the hardware you need. Your trailer wire colors may be different so you have to wire in the new connector function to function, not color to color. To determine the functions of the wires, touch each...
    view full answer...
  • Does Trailer Wiring 7-Way Upgrade Kit # ET7WK Come with Ring Terminals
    Actually the Trailer Wiring 7-Way Upgrade Kit # ET7WK that you referenced comes with the needed ring terminals so you would not need to provide any. The two sizes though are 3/8 and 3/16.
    view full answer...
  • How To Replace a 4-Way Trailer Connector with a 7-Way Trailer Connector
    The best option we have for you to upgrade the 4-way trailer connector on your trailer to a 7-way trailer connector is with the Trailer Wiring 7-Way Upgrade Kit part # ET7WK. Once you have this all you need to do is run the wires from the trailer lights to the junction box and then from the junction box to the trailer connector. Inside the junction box, the terminals are labeled by both wire color and function. However, when running the wires from this trailer connector to the junction...
    view full answer...
  • Which Axle (if only one) Should Have Trailer Brakes on Tandem Axle Trailer
    We recommend putting the brakes on the axle that will have more of the cargo's weight on it. For a utility trailer that's typically the front axle. Typically the only time you see the brake axle as the rear axle is if it's a boat trailer since the weight of the engine is behind the axles.
    view full answer...
  • How to Charge a Trailer Battery Using a 4-Way Trailer Connector
    The best way to maintenance charge the 12 volt auxiliary battery on your trailer would be to upgrade to a 7-way trailer connector. For this, I recommend using the Trailer Wiring 7-Way Upgrade Kit part # ET7WK. The 12 volt hot lead (black wire) that feeds into the trailer connector will need to connected to the positive post on the battery and will work to provide a maintenance charge. However, if you need to provide an actual charge then you will need to use a battery charger instead like...
    view full answer...
  • Brake Lights on Vehicle Light Both Brake and Turn Signal Lights On Trailer
    Thank you for describing the problem you are having with your trailer. I noticed you said that the amber lights were on with the brake pedal applied. Are you referring to the amber lights on the vehicle or amber lights on the trailer? If they are on the vehicle then you would need to take it to an automotive repair shop for inspection but if you're referring to them on the trailer then it sounds like you have a separate lighting system which means the brake and turn signals are on different...
    view full answer...
  • Organizing the Wiring on a Gooseneck Horse Trailer with a 7-Way
    If you check out the attached picture it shows how the wiring on a trailer should look. If you already have all of the wiring that you need for a 7-Way and you are just wanting a way to organize it then I recommend installing the Trailer Wiring 7-Way Upgrade Kit # ET7WK. This kit includes a junction box and ring terminals which make connecting the wiring to a 7-Way connector very easy and helps to keep things organized. The installation locations are labeled to help take the guesswork...
    view full answer...
  • Running Power to Trailer for Lights from Vehicle with 4-Way Connector
    Yes, we have exactly what you need to run some wiring to power your LED lights on your trailer! The best way to go about this would be to install the Trailer Wiring 7-Way Upgrade Kit # ET7WK on your trailer for a 7-Way and then installing the Adapter 4-Pole to 7-Pole and 4-Pole # 37185 on your vehicle side. You will then run power to the 12V power pin on the adapter using 10 Gauge Wire # 10-1-1 Ring Terminals # 44-5310A and a 20 Amp Circuit Breaker # PK54520 from your battery. For...
    view full answer...
  • How to Tow a 2017 Kia Rio Behind an RV
    From my research your 2017 Kia Rio cannot be flat towed with all four wheels on the ground whether it has a 6-speed manual or 6-speed automatic transmisison. It must be towed on a tow dolly or a trailer. We offer tow dollies from Roadmaster that you can use. Parts # RM-2000-1 and # RM-2050-1 both can be used with your Rio. The main differences between the them are the weight capacity and that # RM-2000-1 has self-steering wheels. In order to power the brakes on either dolly you need...
    view full answer...
  • Re-Wiring Trailer for Tail Lights and Electric Brakes
    To completely rewire your trailer I recommend using the Trailer Wiring Kit # ET7WK. This includes a 7-Way connector, a junction box to provide you with a clean setup, and all the necessary hardware. You will then just need additional 16 gauge wiring # 16-4B-1 for the light circuits and 10 gauge wiring # 10-1-1 for the brake and 12V power wires, both of which are sold by the foot. I have attached a great install video along with a standard trailer wiring diagram that you can use for reference....
    view full answer...
  • Troubleshooting New Trailer Brakes that Don't Engage with Multiple Trucks
    You know the brakes themselves work because you can test them with a battery. It sounds to me that the issue is in the trailer's connector or the wiring. I would try replacing the connector with something like # ET7WK. You can try testing for the problem in the connector by plugging the trailer into a truck and then using a tester on the brake wire on the 7-way just a few inches behind it.
    view full answer...
  • 7-Way Wiring for 2000 Chevy Silverado
    If you are looking to install 7-way wiring on your 2000 Silverado you can use part # PK11898 if there is a bundle of wires above your spare tire, or part # 30955 if there is a round plug with a cap on it above the spare. These items complete the factory wiring setup. If the truck has a working 4-pole harness like # 119147KIT you can upgrade this to a 7-way using kit # ETBC7. This will use your existing 4-pole wiring and will allow you to add the extra circuits found in the 7-way format....
    view full answer...
  • Wiring Kit to Convert Trailer Wiring to 7-Way Format
    Trailer Wiring 7-Way Upgrade Kit # ET7WK allows a trailer's existing 4-pole, 5-pole or 6-pole wiring to be re-formatted to the 7-way RV standard to match the 7-way socket on your Silverado. The kit includes a male trailer plug and cable, hardware and ring terminals to allow you to wire both the male plug/cable's leads and the existing trailer wires together inside the included junction box. The kit also includes protective wire loom to keep any exposed trailer wiring protected from road...
    view full answer...
  • How To Replace a 4-Way Taylor Trailer Connector With 7-Way
    The wires on your 4-way trailer connector are as follows: White - Ground Yellow/Brown - Left Side Trailer Running Light Green/Brown - Right Side Trailer Running Light Yellow - Left Side Trailer Stop/Turn Light Green - Left Side Trailer Stop.Turn Light Red - Misc. In order to rewire the above to a standard 7-way trailer connector you just need to match the wires based on function but the yellow/brown and green/brown wires can just be joined as one and then attached to a running...
    view full answer...
  • Wire Function to Replace a Trailer's 6-Way Connector with a 7-Way
    Are you trying to replace a 6-way on a trailer with a 7-way connector, like part # ET7WK? Traditionally, the white, brown, green, and yellow wires are as you listed them. Then the other 2 wires are for electric brakes and a 12 volt auxillary circuit. However, wire coloring is not always standard and can be very unreliable. Instead I recommend testing each circuit for function. Use a 12 volt battery and connect the negative pole to a good ground and then connect each wire, one at...
    view full answer...
  • Kit to Upgrade 5-Way on Trailer to 7-Way
    We have a kit that's designed for exactly what you are looking to do. The Trailer Wiring 7-Way Upgrade Kit part # ET7WK is designed for upgrading a trailer from a 4-way to a 7-way but can also be used with 5-way wiring as well very easily. I attached an install video for this kit for you to check out as well.
    view full answer...
  • Parts Needed to Totally Rewire Trailer
    The Trailer Wiring 7-Way Upgrade Kit # ET7WK is a good place to start. It gives you a new 7-way and wiring to a junction box where you can then wire all of the circuits to. Additional hardware that you may need is 3/16 Inch Ring Terminals, # 44-5310A, 1/4 Inch Ring Terminals, # DW05702-1, 12-10 Gauge Butt Connectors, # 05732-2, 16-14 Gauge Butt Connectors, # 05731-5, and electrical tape. And finally 10 gauge wire like part # 10-1-1 which is sold by the foot and 12 gauge wire # 12-1-1....
    view full answer...
  • Troubleshooting P3 Brake Controller Not Connected Error on a 5 Prong Boat Trailer
    Don't worry, I can help. The reason your brake controller is reading "no trailer connected" is because the 5- to 7-way adapter you are using cannot read electric brakes. There is no 12V power or brake wire signal on a typical trailer end 5-way. Your best bet is to add a 7-way connector to the trailer like # ET7WK. This kit includes a 7-way, a junction box, and hardware. To complete the connection you will want to run 10 gauge wire like # 10-1-1 from the junction box to the brake...
    view full answer...
  • Replacing a 7-Blade to 6-Square Trailer Adapter on a Pop Up Trailer
    What you have is an adapter that goes from a 7-way blade connector to a 6-way square connector. A few pop up trailer manufacturers used it but unfortunately replacements can be hard to find. In my opinion you would be better off cutting the 6-way off of the trailer and just hardwiring in a 7-way connector and not deal with the adatper. The easiest and cleanest way to wire in the new 7-way is with a junction box. We have part # ET7WK that includes everything you need. I've also linked...
    view full answer...
  • Kit Needed to Convert 4-Way of Trailer to 7-Way
    We have a kit that is designed specifically for converting the 4-way of a trailer to a 7-way. For that you would want the 7-Way Upgrade kit part # ET7WK which comes with everything needed. I attached an install video for this kit for you to check out below as well.
    view full answer...
  • 7-Way and Junction Box Kit Recommendation for Trailer with 4-Way
    I'd go with adding a junction box and a 7-way but still using your current light's wiring if it's still good. For that we have the part # ET7WK which matches what you need perfectly. It's designed for upgrading a trailer with a 4-way to a 7-way and comes with a junction box and 7-way. I attached an install video for this for you to check out as well.
    view full answer...

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Info for this part was:

Edited by:
Lindsey S
Expert Research:
Michael H
Expert Research:
Jameson C
Expert Research:
Adam R
Installed by:
Cole B
Video Edited:
Chris R
Written by:
Amanda M

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