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Trailer Wiring Junction Box - 7 Terminals - Polypropylene

Trailer Wiring Junction Box - 7 Terminals - Polypropylene

Item # 3375601100
Our Price: $12.69
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Durable polypropylene box creates a fast, easy way to connect the wires from the trailer connector to the wiring for either a 6-way or 7-way connector. Makes replacing your trailer's connector simple. 1-800-940-8924 to order Buyers Products accessories and parts part number 3375601100 or order online at Free expert support on all Buyers Products products. Great prices and Fastest Shipping for Trailer Wiring Junction Box - 7 Terminals - Polypropylene. Accessories and Parts reviews from real customers.
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Buyers Products Accessories and Parts - 3375601100

  • Trailer Wiring
  • Junction Box
  • Buyers Products

Durable polypropylene box creates a fast, easy way to connect the wires from the trailer connector to the wiring for either a 6-way or 7-way connector. Makes replacing your trailer's connector simple.

  • Electrical junction box consolidates your truck's wiring
  • Polypropylene construction
  • Number of terminals: 7
  • 1-Year warranty

5601100 Buyers Products Electrical Junction Box - 7 Terminals - Polypropylene

Video of Trailer Wiring Junction Box - 7 Terminals - Polypropylene

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

Video Transcript for Buyers Products Trailer Wiring Junction Box Review

Shane: Hi, I'm Shane with Today, we're going to be going over the junction box for trailer wiring. This box is going to be a polypropylene box, very durable plastic. It's made to be mounted on the frame of your trailer. And what this does, this allows you to wire your 7-pole plug separate from your trailer wiring. So, say we have our 7-pole wiring, it comes loose, drags the ground, or gets damaged.

We're not going to have to cut it off of our wiring coming from our trailer in order to replace the plug. We can simply take it off of the pegs here, replace our plug, and add new ring terminals, stick it right back in the box and connect it directly to our wiring.And with a trailer this size, or larger trailers, if you maybe want to add a breakaway switch, it's very easy to run that wire over and connect it directly on to the brake wire coming off the 7-pole plug, without having to cut the wire coming out of there and splice them together. Depending on how your trailer is set up and how your 7-pole plug wiring is done, it's going to have to be tested. Your box is going to come with a sheet inside, it's going to look like this, on how it has to be set up.However, this is not always accurate with the plug itself. If you have the 7-pole plug, it may be wired just a little bit different than this.

Trailer wiring needs to match whatever the functions are coming off of your 7-pole plug coming from the vehicle. You're going to have a power wire coming in. You're also going to have ground. The ground coming off the center post needs to be grounded to the frame. So you're not only grounding the 7-pole plug, but you're also grounding this setup here on the box.The box is going to come with five rubber knockouts.

You can either cut these or they will also come with another set that already has a hole already open. I, myself, just like to cut an X in it and run my wires through it, it kind of helps it seal a little bit better. These will seal underneath the lid. Each place that your wire comes in, you're also going to have a metal clamp with two screws, and that's to hold your wiring in place to keep it from coming out. The lid you can see here, it's got a groove, and what that does is it seals around this edge to keep any water or anything like that out.It's going to come with two large screws to hold your lid in place.

Again, I'm Shane with That's going to do it for our look at the trailer wiring junction box..

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Customer Reviews

Trailer Wiring Junction Box - 7 Terminals - Polypropylene - 3375601100

Average Customer Rating:  4.7 out of 5 stars   (200 Customer Reviews)

Durable polypropylene box creates a fast, easy way to connect the wires from the trailer connector to the wiring for either a 6-way or 7-way connector. Makes replacing your trailer's connector simple.


The junction box provides adequate room for wiring terminations and weatherproof covering of them. The harness for transmitting power to the trailer is of robust design with LED lights indicating proper power to the various end uses. A stainless steel u-bolt was used to secure the harness to the trailer frame and thereby eliminate stress on the junction box. Stainless steel machine screws were used to attach the Breakaway Battery Box to the trailer frame. A stainless steel quick connect will be used to secure the Breakaway switch to the vehicle. The red lead supplies 12 volt power to the Breakaway battery.


solved the nasty wire mess problems,, you have bolts to tie each ring terminal to...


Nice junction box. Used this as a junction/access point for my ‘18 Equinox flat tow setup. It houses my 5way conductors for tail lights, the Roadmaster battery charge line circuit breaker and fuse lead to my accessory +12v port that I’ll plug my Brake system into. Also added a cut off toggle switch on the charge line when not in use.


Doing business with Trailer is good.
product at a fair price.


Trailer sits outside 24/7, always bone dry inside. I put a little silicone around the rubber grommets for good measure.


I have not installed yet, but the product arrived in good condition. There are lots of options for installation and lots of grommets for the wiring to access the terminals.


The terminal box is handy little item to have when wiring a new 7 way plug on your trailer.


This is an excellent junction box.


Fast shipping and seems to be good qual ity


All my trailer parts for a new build keep coming in from etrailer , my go to online store. Everything needed for building and maintaining trailer etrailer has. I have been dealing with etrailer for several years now and have never been disappointed.


Awesome piece of equipment!! EXACTLY what I was needing!! Replaced the old torn up box and this box worked perfect!! Fast shipping and great communication, as usual!! Thank you etrailer!!



One year later and the box is still holding up strong! Great product!


Great product. Glad to see it came with so many ways to install the tow vehicle cable and trailer wiring bundles. Also good to see two sizes of waterproof graumets to ensure best water tight conditions.


After a year doing its job well.


Was exactly what I needed for adding electric brake axles to my boat trailer. I'm very happy with this product and with the service from


I needed a trailer wiring junction box because my existing one rusted out. I looked all over, including the place where I bought the trailer, but was unsuccessful. I stumbled onto the etrailer site by luck and was amazed they had what I was looking for. I took some photos of my unit and compared it to what they were offering and it appeared pretty identical so I went ahead with the purchase. This company is very responsive and easy to deal with. The shipping was quick, the price was very fair, and the staff is attentive and professional. I’m glad I discovered etrailer.


This is the mechanism to rewire an elderly auto hauler, that has wiring faults.
Better to spend the $$ and do the job correctly, than faulty shortcuts. The old Junction mechanism is not viable. This should fit the bill.
Will comment further after the dasterdly deed has been done


Beside using these boxes on trailer tongues, they're also handy at the rear of trucks. Heavy duty trucks also use seven wires. Different plug, round pins. I've used similar boxes to tidy up the wiring on many big vehicles. These seem to be decent quality at a fair price. I got this one to add a trailer connection on a school bus converted to a camper. It was shipped promptly, UPS sat on it for a few days.



A year later, all is well.


My new towing vehicle required a longer cable so I purchased the cable below as well as this junction box to make my life easy. Installing this junction box allowed me to make some corrections based on vehicle side wire colors and trailer wire side colors which differ. I mounted it on the side of the trailer to hold it in place firmly and it works perfectly. This is a great way to have a neat installation that looks like it is completely sealed from weather and insects. Highly recommend this.
Hopkins 7-Way Blade-Style Connector w/ Molded Cable and LEDs - Trailer End - 6' - Auto Standard


Perfect! Works like a champ, for years I've used plastic conduit and electrical tape, it never holds up and looks bad. This junction box made my trailer rebuilt project look professional!



Great! Still water proof and working fine.


Worked out perfectly


This junction box was a great addition to my trailer wiring as it provided a watertight location to make up connections without splicing wire. A suggested enhancement would be stainless mounting screws to eliminate the rust potential.


Does everything you could ask a 7 wire polypropylene wiring junction box to do.


Made connecting trailer wire clean and neat. Well organized way to make the splices needed.


Ordered this with multiple things. Only thing I received was the small disconnect switch with the cable. Had to wait on another whole kit to ship.


My trailer's stock surge brakes worked pretty well but dragged the brakes driving down hills, did not work while backing down boat ramps, and provided no backup if my vehicle brakes failed... So I got this EOH system to solve those problems.

I only test-drove the finished upgrade once but it seemed to work fine. Note that in my 2018 Ram 1500 with integrated trailer brake control, I needed to set this up as "EOH heavy" even though my boat + trailer are under 6000 lbs.

I wanted a solid, clean install, so I had a bracket made and welded to the trailer out of harm's way and above the possible high water level, even though it's all theoretically waterproof.

Other considerations:
- I was able to re-route the stock steel brake line right to the brake unit.
- I had to buy a new 7 pin trailer harness to replace the stock 5 pin one. I made a conversion harness to go from the new wiring to the stock trailer wiring.
- I locked out the original surge system by replacing its guts (master cylinder, spring, etc) with a steel bar that goes between the front and rear pins.
- I hid the breakaway switch inside the tongue and ran the new breakaway cable where the original one went.
- I safety-wired the brake reservoir cap to prevent its loss or vandalism. It just didn't seem secure to me. Easy fix!

I think it looks good and seems to work well. I expect it will last many years. I gave it only 4 stars as the brakes have some lag (1/2 second?) before I can feel them working. I was led to believe the brakes would be instantaneous and I "would not feel the trailer" (possibly like the electric brakes on my other trailers) but it's not quite that perfect. But maybe I'm being picky! I'd choose this very system again.

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See what our Experts say about this Buyers Products Accessories and Parts

  • Dimensions of the Trailer Wiring Junction Box
    The Trailer Wiring Junction Box # 3375601100 has dimensions of 8-1/2" long, 3-5/8" wide and 2-1/2" tall. The distance between the mounting holes (center of hole to center of hole) is 7-13/16". I have included a video that shows these measurements starting at the 2:15 mark of the video.
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  • Comparing Trailer Wiring Junction Box 3375601100 and Trailer Wiring Junction Box 38656
    The Trailer Wiring Junction Box part # 3375601100 and Trailer Wiring Junction Box part # 38656 are both pretty standard 7-terminal junction boxes. The latter is slightly smaller so there will be more places to mount it so that is what I recommend but you really can't go wrong with either option.
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  • How to Run an Electric Jack Off of a Trailer Battery and a 7-Way Connector
    The easiest way to power your electric jack off of the 7-way and/or the battery is to install the Trailer Wiring Junction Box - 7 Terminals item # 3375601100 and connect your jack to the 12v circuit that your battery would also be connected to. This would allow your jack to draw power from both your tow vehicle's 7-way or your trailer's battery. This inexpensive junction box provides a secure location for all of your 7-way connections. I have linked a review video below so you can see...
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  • Taillight Converter Needed To Separate Brake Lamp and Turn Signal Circuits
    The Curt # C56196 2 to 3 wire taillight converter is exactly what you'll need to split out the turn signal function from the brake lamp circuit. However, keep in mind that the # C56196 is NOT compatible with LED lamps, unfortunately we don't offer a taillight converter at this time that is compatible with LED lamps. You would wire the converter inline with the right and left turn and brake circuits. You will want to install the converter some place where it's protected from the elements....
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  • Correct Replacement 7-Way Trailer Connector Pigtail for Travel Trailer
    The pin-out for a 7-way trailer connector is pretty consistent. Unless the connector was wired incorrectly, it should be wired as shown in the provided photo showing the correct pin-out. What CAN vary is the wire color codes, which are also shown in the photo. The # H20046 pigtail would work just fine for you, just be sure to follow the wire color code shown on the linked product page. I'd also recommend a junction box like part # 3375601100. A junction box provides a centralized place...
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  • Hopkins 7 Way Molded Plug Wiring and Junction Box for a Boat Trailer Wiring Harness
    There's not a universal way that trailers are wired. I have attached a diagram showing the three typical ways and this should also help you to connect to the 7-way harness you purchased once you identify your wires. Yours is obviously different, thank you for including the picture. To identify the wires on the trailer you will need to apply 12V power from a car battery to see what function each wire activates. Ground the battery negative terminal to the trailer frame and then one by one...
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  • Junction Box Terminal Post Size for Part # 3375601100
    The ring terminals you want to use with the junction # 3375601100 are the # 44-5310A which have an inner diameter of 3/16 of an inch.
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  • Wiring Harness and Junction Box for a DIY Trailer
    We do have a great wiring harness for DIY trailers. It is the 7-Way Molded Trailer Wire Connector, 4' Long item # H20043. The Pre-wired 7-Way Trailer Connector measures four feet long including the connector. To secure and consolidate all of your wiring connects you will want to use the Trailer Wiring Junction Box - 7 Terminal item # 3375601100. The weatherproof, heavy-duty plastic protects wires and terminals from the elements.
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  • Creating 7-Way Trailer Connection Adaptor for 13-Way European Bike Rack Lighing
    We do not have any European 13 way adapters to make your bike rack lights compatible so you will need to rewire it. So you would need to create a custom adapter using a 7-way connector and probably a junction box to protect an external converter box that you will need to separate the stop light from the turn signal for your 13 way bike rack wiring. For this conversion, I recommend the Vehicle to Vehicle Tail Light Converter # 118158 along with the Wesbar Adapter - 7-Way RV to 4-Way or...
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  • Battery Disconnect Switch for Use on Travel Trailer
    You can use the Marine Battery Switch # 277-000403 for your application but since this item is not rated for outdoor use I recommend using a junction box like # 3375601100 to provide a degree of protection from moisture. The switch housing (not including the knob) is about 1-1/4-inches deep so you'd want to use hardware that is about 2-inches long. If space is available in your battery box you might be able to mount the switch there. In this case a better choice might be the Epicord Battery...
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  • How Is the Mighty Cord 7-Way RV Style Trailer Connector w/ Molded Cable Pinned
    In regards to replacing a trailer connector on a trailer with an option like the Mighty Cord 7-Way RV Style Trailer Connector w/ Molded Cable part # A10-7W8, you need to match wires by function not color. In other words, if there is a green wire on the trailer, you should apply power to that wire to see what light it activates. Then attach this wire to the trailer connector based on the function of the light and how it matches up with the diagram for the trailer connector attached below....
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  • Will The Trailer Wiring Junction Box # 3375601100 Allow For 2 Separate 7-Way Connectors?
    Yes, the Trailer Wiring Junction Box # 3375601100 will have enough room for both the 7-Way Blade # HM20041 and a EZ Connector # 319-S7-10.
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  • Replacement Trailer Side 7-Way Connector with Junction Box
    Sounds like you are missing your trailer connector. I have a couple options for you depending on how far back your wire was cut off. The first is the Pollak Black Plastic, 7-Pole, RV-Style Trailer Connector - Trailer End item # PK12706. This is just the trailer connector itself with no wiring attached. I have linked a diagram of how to connect it to your 5th wheels wiring. The second option is the Hopkins 7-Way RV Style Connector with Molded Cable item # H20046. This provides you with...
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  • Wire Gauge of 7-Way & Junction Box
    While we have an alternative, the part number you asked about has been discontinued. But what you can use is the Trailer Wiring Junction Box # 3375601100 and Hopkins 7-Way RV Style Connector - 8' Long # H20046. This 7-way uses 14 gauge wires for the red, brown, green, and yellow; 12 gauge for the blue; and 10 gauge for the white and black wires.
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  • 2022 Toyota Highlander Wiring for a 7-Way Blade Connector
    I would be happy to help you set up your 2022 Toyota Highlander to haul your new travel trailer. The wiring harness you currently have controls your trailer's lighting functions only. You do not need to rewire your Toyota you just need another harness. The second harness you will need is the Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires item # ETBC7. The kit includes a pre-wired 7- and 4-way trailer connector that mounts easily at the...
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  • Can Trailer 4-Way be Wired to Activate Trailer Brakes
    A 4-way is not able to activate trailer brakes as it is for lighting only, so it doesn't have the ability to carry the signals to your brakes. So what you'll need for your trailer is a junction box and 7-way: - Junction Box - 7 Terminal # 3375601100 - 7-Way RV Style Connector - Trailer End 6 ' Long # HM20086 or 8' Long # H20046 You'll wire your brakes (as well as your lights) directly to the junction box, which the 7-way is hooked up to. What you will need is brake wire, which is available...
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  • Wiring Needed To Connect Can-Am Spyder 5-Pin To Trailer With 5-Pin and 2-Pin SAE Connector
    Most likely the additional 2 wires are a power and ground supply for your trailer. I recommend verifying all the wiring connections for both your Can Am Spyder and the Roll-a-Home trailer on the 5-way circuit to verify they are identical functions. With the 2 additional prongs running to the Junction Box # 3375601100 you should be able to remove the cover and follow the wires to verify they do go to the Brake Controller # 90195. If this is what you have you will need the Adapter # MA69BR...
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  • Should Junction Box be Used For Adding 7-Way & Wiring to Trailer
    For adding wiring and a 7-way to your trailer, a junction box and 7-way connector is absolutely the way to go, because it is the easiest way to connect your wiring. The best option for that is the following: - Junction Box - 7 Terminal # 3375601100 - 7-Way RV Style Connector - Trailer End 6 ' Long # HM20086 or 8' Long # H20046 If you need added components for install such as a wire tool, zip ties, circuit tester, butt connectors and more, you may want to consider getting that in one...
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  • 7 Way Connection with Junction Box With Traditional Wiring Scheme vs RV Wiring Scheme
    I have a solution for you, but we aren't going to have any 7 way connections and junction boxes that are wired with the same color wires/pin locations as the traditional wiring setups you're looking for. I recommend using the 7 way connector # A7WCB and hard wiring your plug the way you want it setup. You can get wire by the foot (12 gauge) # 12-1-1 or (10 gauge) # 10-1-1 and a Trailer Wiring Junction Box # 3375601100 to finish off this project. This will allow you to use the proper gauge...
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  • Parts Needed to Replace 3,500 lb Hydraulic Drum Brakes With Dexter Electric Trailer Brakes
    Thanks so much for that specific info, and for your brake flange distance and drum diameter, you are right on with the Dexter electric brakes # 23-468-469 working for you. Along with the brakes, you'll also need the wiring, 7-way connector, and breakaway kit to complete the transition from hydraulic drum brakes to electric trailer brakes. - Dexter Nev-R-Adjust Electric Trailer Brake Kit - 10" - Left and Right Hand Assemblies - 3.5K # 23-468-469 - Bright Way Push-to-Test Trailer Breakaway...
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  • Parts Needed to Add Brake Controller and 7-Way to 2002 Jeep Liberty & Trailer
    I can make a list for you of all the parts needed to add a brake controller and 7-way to your 2002 Jeep Liberty, and the prices can be found either on the product page or by scrolling down where the parts will be listed under "Products Referenced in This Question". So exactly what you will need for your 2002 Liberty is the following: - 4-Way (if your Jeep does NOT have the factory tow package): T-One Vehicle Wiring Harness # 118524 or (If your Jeep DOES have the factory tow package): Hopkins...
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  • Can Junction Box be Submerged When Rewiring Boat Trailer
    You can re-do the wiring on your boat trailer with a junction box, but a junction box cannot be submerged as they aren't waterproof. So if you are able to place the junction box in a location that allows it not to be submerged, the best option is the Trailer Wiring Junction Box # 3375601100. This comes with ring terminals and if you need wire we offer it sold by the foot with 12 Gauge # 12-1-1, 14 Gauge # DW02413-1, 16 Gauge # DW02359-1. You may also need Wire Loom # 459075-1 and a connector...
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  • Electric Trailer Brakes For 2,000 lb Jayco Pop-Up Camper
    We have exactly what you need to add electric trailer brakes to your 2,000 lb Jayco pop-up camper, and I'll go ahead and list out all the parts for you: - Electric Trailer Brake Kit - 7" - Left and Right Hand Assemblies - 2,000 lbs # AKEBRK-2 - Mounting Hardware for 7" Brake Assemblies # BRKH7 - Deka Jacketed 2 Wire, 10 Gauge, Brake Wire - per Foot # 10-2-1 - Brake Adjustment Spoon for Drum Brakes # W80630 - Hopkins Engager Push-To-Test Trailer Breakaway Kit # 20099 - Junction Box...
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Info for this part was:

Employee Jameson C
Expert Research:
Jameson C
Employee Cole B
Installed by:
Cole B
Employee Shane H
Installed by:
Shane H
Employee Chris R
Video Edited:
Chris R
Employee Daron K
Edited by:
Daron K
Employee Brian T
Written by:
Brian T
Employee Jacob H
Video by:
Jacob H

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