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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.
Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Shane: Hi, I'm Shane with etrailer.com. 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 etrailer.com. That's going to do it for our look at the trailer wiring junction box..
Average Customer Rating: 4.7 out of 5 stars (53 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.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.
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!!
BrianB - 06/17/2020Beside 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.
Chuck - 01/31/2021
Installation was a bit tricky as the wiring diagram instructions didn't quite match the truck(s) we use wiring. But figured it out and it has been working great since. Purchased it because original plug on trailer was too short and kept pulling free from trucks and dragging on ground.
Just what I was looking for, needed to rewire my Army truck tail lights and this box fits a treat. and is the size that I can hide from the rivet counters. Thanks again and other items I have had from you in the past.
John G - 05/19/2020My 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.
Used this box to add electric brakes to my 16ft utility trailer. I chose this box because it was made from polypropylene, and in my experience, weather’s very well. It made a very clean installation of all the new wiring.
Great way to re-wire a trailer. The box is large enough that I was able to bring individual wires for each side marker and tail light into the box so that their would not be any splices outside of the box.
These J boxes are of top quality. I cant think of anything I ever bought from you that was sub grade. etrailer in my go to place for all my trailer needs. Thank you!
Easily bolted to the trailer and made adding electric brakes to my boat trailer a breeze.
I've used these boxes on many trailer repairs over the years. They are easy to mount, easy to hook up new wiring and stay water resistant.
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!
Perfect for minimal wiring. Used these for my trailer brakes, one one each side. Works fine, been to the salt flats several times and the brakes still work. =)
This terminal strip box is well designed. It has seven studs with washers and nuts plus a very clever arrangement for getting cables into the box - two on one end and one on each of the other three sides. Each hole has a blank (closed) or holed opening to accept a cable. Pretty clever. The slots in the box fit these plastic grommets and allows either an opening or a covered slot to be used. I mounted the box in a horizontal position on the bulkhead near the battery supply for the breakaway switch. I ran the main 7-wire cable to the bottom and spread it along the studs according to the diagram for the color scheme. I ran the cable from the trailer to the right side (where the two cable entries are located) into the upper access hole and distributed each wire to the appropriate stud. This allows any other application to access the power source such as lighting or other accessories. I used only lights, but I had to connect the power for the lights to the blue wire out of the battery box since it is the only wire with 12 vdc on it all of the time. When the cable is hooked to a vehicle, the 12 vdc connection has 12 vdc, but when it is not connected, the 12 vdc connection is not used and shows only 1.5 vdc. This is the black wire on the battery box. The white wire is ground - between these is the power for the battery charger. The blue wire, however, has 12 vdc on it at all times, so disconnect the battery before hooking it up. And don't connect the blue wire to the blue wire of the cable from the vehicle. The blue wire must be connected to one of the wires on the breakaway switch (I used a red wire to the switch and a black wire back to the box) and the return wire is connected to the blue wire for the brakes. So when the plug is inserted in the breakaway switch, the switch is open and no power applied from the battery to the brake solenoids. When the plug is removed, the switch is actuated and 12 vdc is applied to all of the brake solenoids in parallel. The one side of the switch is hot all of the time unless the battery is disconnected.
The Junction Box has worked out very well for me. Taping the color code strip in the box is a big help in keeping everything organized and easy to troubleshoot later.
I have used these before and they are great for a trailer wiring project. However, you must be careful when mounting to ensure that you do not crack the housing. If the mounting surface is not perfectly flat and/or the mounting tabs flex it will crack. i mounted two on my trailer and one cracked the other did not. A little silicone will seal it up!
No issues with this box. Makes it convenient when adding several plugs on a trailer.
Works well, could be a bit larger. Gets tight when you fill it with wires.
Used this box under my truck to connect both the bumper rv plug, and the fifth wheel rv bed plugs to the truck wiring. Made the job easy!!
The quality was good. My only complaint was a combination of metric and sae hardware. The nuts on the terminals were 3/8". The cover lag bolts were 10mm. Other than that, I have no complaint.
Just got in my travel trailer today. Good sturdy box with plenty of room for all wiring.
I chose this box because it was economical and I didn't need it to be water-tight because I mounted it inside my old camper. My priority was to organize a mess of wiring and to make it simple to switch the type of tow-vehicle connector. I'm very happy with the result. Those little nuts that fit on the terminal posts are 3/8 inch - so get a socket that size to help you screw them on and off (with your fingers not a wrench). And be prepared for those nuts to fall down and roll into hard-to-reach places inside the box. If you have a magnetic retrieval tool you can save some frustration.
Top quality product, fast delivery.
Heavy built & perfect for what we needed. Just the junction box--no wiring or plugs. Arrived quickly!
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