Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
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Spectro/
Wiring/
Junction BoxItem # 38656
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This Spectro trailer wiring junction box provides 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.
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Video of Trailer Wiring Junction Box
Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Previously on This Old Trailer we installed the backing plates in the hubs and on this episode we are going to install the wiring. Basically what we are going to do is hook up the wires for the backing plates and run them up to the front of the trailer. We are going to install junction box part number 38656. It is a good idea to have a junction box in case you ever have to change out the lead going up to your truck. It is easily changed out especially if you have a wiring harness that is all molded into one piece. We are going to upgrade this trailer with our junction box so we can do that. Install it in this location in the channel on the tongue. Hold the box up to it, mark some holes out, and drill it out to 1/ 4 inch bit and use 1/ 4 inch hardware to hold it in place. When we get the hardware installed we can tighten it down into place. 01:29
Next we need to start running our wires from the junction box and we will follow the existing holes that are in the frame down to our brake axle. The next thing we will do is make the connections to yhe junction box. We are going to peel back the gray cable a little bit and then we are going to run our white cable to ground that is labeled in the junction box. We are going to treat the junction box just like the inside of a 7-pole connector. White is going to be ground and blue is going to be for electric brake lead, however on the cable we have got a black and white wire. White is going to stay white to ground while the black wire will go to blue in the junction box. The junction box also comes with different grommets. You can see here this one is opened up for the cable and we will just replace the one that is existing in the box right now. We will just pull out the original grommet and slide in a new one. 02:39
We will also clamp our wire in position with the hardware provided with the junction box. We will add some ring terminals to our wires and attach them in to proper position. Next I am going to make a connection to the first brake hub and make sure you have plenty of slack so you wrap the wires where they will not get mashed up against the frame. We will make our connections and just leave plenty of slack and then later we will come back with some loom clamps. Lets cut back some of the insulation and we will make the wiring connections to the cable. The actual connections to the wire we are just going to use what is typically called a quick splice and we are just going to use that to connect our wires together. The brake magnet itself has two green wires. It does not matter which one goes to power as long as you have a secure connection one is going to power and one is going to ground. It does not matter on the green. Again on our second brake hub we will cut our wire to length. Make sure we have plenty of length left over so we have room for suspension movement and make sure it does not get smashed again. The same thing as before, it does not matter which wire goes where on the magnet. Just make sure one goes to ground and one goes to power. In this case we will be using the butt connectors to make our attachment. When using a butt connector with a smaller gauge wire like we are doing here, it might be a good idea to take the wire and fold it over itself and then install it in the butt connector and then crimp it down. 04:56
We will run our 7-pole cable up to the front of the trailer by the coupler. We are going to run it through the factory guide and then run it into our junction box. We will start making our connections for our brake leads inside there. Slip on the grommet for the wire cable and just like the other side put it into place. Next we will make our wire connections up from our 7-pole cable. White is still going to be ground so we will run it to our original white wire and that is labeled for ground. We will run the blue wire to where the black wire was ran to and that pin is labeled blue. We will make our blue and black wire connection permanent and with our extra bits of wire we have we can use that to make our jumper for ground. We will use the grommet on the top and poke a hole through it and the white wire through there. On the white wire we need to make a jumper off that post on to the frame of the trailer so the trailer can get ground from that point and then we can make that connection permanent. We have the left over wires and our 7-pole harness. What those are used for is the lighting on the trailer itself and for the purpose of this video we are just going to these both alone for now because we are only dealing with the electric brake part. Our next thing to do is apply the 12 volt power to our circuit and make sure the brakes work. Spin the hub with the power off and then when you apply power the hub should stop. That will finish our installation of the brakes on a standard trailer using a junction box and a molded 7 way connector. That finishes this episode of This Old Trailer adding electric brakes.
Average Customer Rating: 4.8 out of 5 stars (445 Customer Reviews)
This Spectro trailer wiring junction box provides 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.by: Wayne M08/07/2014
This trailer was built from scratch using only the metal frame. I purchased some items from etrailer an was very satisfied with the products. 144937
Great job! Looks like a high quality build.
-- comment by: Mike D - 03/26/2015Its still working great.
Wayne M - 08/07/2015by: Michael C.11/17/2012
I purchased this product after researching current trailer rewiring methods. I recently had my entire 18' trailer wired and upgraded. The trailer is 8 years old and I wanted to replace the original 4 way trailer harness which the trailer manufacture had surrounded in electrical tape which also needed an adapter. After some research, I opted for this 7 way pigtail (50-67-005) which is the connector I needed my trucks and this junction box. (all contacts were current) The junction box is sturdy and well made, we installed 7 way wire within the box with a snug fit. The trailer now has a clean professional appearance and most test functions can be performed from the junction box location. The junction box was installed behind the trailer tongue frame to minimize the weather elements. This product appears to seal well as the product description indicates. I am very satisfied with this product and Etrailer's customer service. 59585
by: Sherman M.11/04/2013
We wanted both a 7-wire and a 4-wire plug on the same trailer. This junction box made the installation very easy. If your connecting the Hopkins 7-wire harness to this box, you'll probably have to ignore the wire colors names and just use the location (R Turn, etc.). Both are marked on each terminal. There are 5 different openings to choose from to route the wiring to this box and it comes with both rubber grommets to run wiring through and rubber plugs for the openings not used. A downside is that only the side with 2 openings has wire hold downs on the inside. It would have been nice if at least the opening on the opposite end also had such a feature. It's fairly water tight and installed easily onto the frame, under the trailer. Because it's lightweight plastic, I'm not so sure how long it'd last in the direct sunlight if it was mounted on the tongue or other exterior location. 106238
by: lwal05/22/2014
The wiring junction box is high quality, watertite, and makes for a professional wiring of brakes and lights. I am in the process of converting all my trailers to this junction box. 132015
This an excellent device that makes trailer wiring easy an easy to maintain. Highly recommend the box if one has the room to install it which some of my trailers dont.
lwal - 05/27/2015by: Dennis W05/30/2015
I wired plenty of trailers in the past the old way connectors and tape but this box is in my opinion a must have! Easy to wire nice construction and for the price it keeps every thing out of the weather and organized. Thanks Etrailer! 198648
Thank you for the concern, Everything I purchased from you are working as they should. VERY HAPPY with all.
Dennis W - 06/17/2016by: Matt W08/02/2016
Bought a fifth wheel camper last fall and the trailer cord was stiff enough that I could only find one position it liked to be plugged into the socket in the bed. Decided to replace the cord and get rid of the OEM metal junction box. I ended up ignoring the color code molded by each of the terminals and just went by the functions at were molded by the terminals. Everything is nice and neat with ring terminals connected to each terminal stud. Trouble shooting will be a breeze and future cord replacement will be easier. I like the fact that it eliminated a junction box full of wire nut connections. I tightened the lid screws until snug and did not have any issues. Grommets were sufficient and sealed up tight. I really wish there would have been a screw down cable clamp on each end instead of both on one end. 278702
by: Carl12/20/2016
For the price, I expected this to be higher quality. The junction box is functional and the labeling is excellent, however, the plastic is weak and the screws provided tend to tear up the plastic and may not work well at all if the box is opened or the cables are adjusted more than once. Problems with the junction box: - Strain relief screws protrude through the bottom of the box, compromising the moisture seal. When tightening the cable clamps, the screws are too long and cut through the bottom of the box. - Plastic is weak: When tightening the screws that hold down the lid, the bottom of the box becomes distorted. - terminal block is not well secured to the box. Only two rivets hold the terminal block to the box and even moderate torque on the terminal screws causes the terminal block to wiggle. 326689
by: Robert S12/31/2016
Thanks for your help with parts for my trailer build. My wife and I are still making custom cabinets out of curly maple. We hope to finish this winter. We have taken it out 7 times this season. Thanks again. 329116
by: John W.10/31/2012
Great looking and a smaller package than I thought. Fits better for the application. 58490
After a year in service all is still working fine. I will have to say that the rubber grommets are the weak link. They seem to be degrading a lot faster than I expected. Should be made of a material that is UV stabilized.
John W - 05/01/2014by: Jason H03/19/2015
This product is a great way to fix a spot in the wires where they dragged on the ground. I simply cut out the bad areas and attached proper size wire nuts and secured this junction box. 179837
The box has continued to keep the wires working, safe and dry! Thank you for this great product!
Jason H - 03/18/2016by: Joel j07/03/2015
Junction box was great had it installed and wires hooked up in a little over an hour. Service and shipment was better than expected. Will definitely use etrailer for more of my needs, very good company. The only thing that took a while was the molded seven connector wire colors don't all follow standards, but a test light and a few minutes and it was figured out. 209099
by: Loren04/01/2013
I installed this J-box over the weekend, and overall I'm pleased with its construction, particularly quality-per-dollar. The one 'concern' I have is that the grommets seem rather frail. After sliding over the 7-way wiring (H20046), I ripped the grommet as I slid it into the box. My guess is that it'll stay water tight for a minimum of several years living outdoor in the UV light, at which point I'll figure out some other way to keep it water tight, if needed. The J-box fits neatly inside the channel-iron frame of my trailer. The next time I need to wire a trailer, I'll certainly install one of these; a great value compared with piecing something together from the electrical supply section of my local Big-Box Store. 73670
by: Al07/19/2013
excelent just what I needed glad I found it on you product line I tried to find something to use for splicing the wires under my trailer Ialso like all the tech. information you have available on your web site 90534
perfect
Al - 01/17/2015by: Ron C06/06/2015
Wiring junction box received quickly and as ordered. Already installed with excellent fittment and great quality. Thanks! 201134
Installed very easily, still works greaT!
Ron C - 06/05/2016by: Steve S.11/25/2013
I love these boxes. I've repaired numerous trailers my sons and I own, including cargos, flat beds and horse trailers. I really like the grommet locations, cable clamping and posts for wire connections. There is plenty of room inside to neatly route wires. 108409
by: Dave S.08/29/2013
A decent product - perfect application if you're wiring a trailer with electric over hydraulic brakes I purchased this to replace the same box I bought just a few weeks ago where the plastic top cracked. You must be very careful not to overtighten the top 2 screws. After mounting the box on the trailer and doing all my wiring terminations, I put the cover on and screwed it down - everything was fine. Came out the next morning and the cover had cracked sometime during the night due to the tightness of the screws. I'm thinking of adding some rubber grommets to spread the load. It might also work better if there were 4 screws instead of 2. 97519
by: Money09/30/2013
Exactly what I needed - direct replacement on my PJ Trailer. 101994
Working out great. No problems at all and looks factory.
Money - 09/30/2014by: Chris O12/16/2016
Ordered lots of parts on Monday, received most of them by Thursday. The received parts were well packaged and undamaged. A few of the parts they didn't have in stock so they had those drop-shipped to me which should be delivered in the next couple of days. No supplier I have ordered any parts from has such a great technical reference web site or personal customer support. Yea, Rebecca - Well Done! Yes, I'm very happy with the pricing. Thanks for your great support and I look forward to doing business with them again. More info to follow as soon as I can get the parts installed on my trailer. 326667
by: Hazel Self03/10/2014
Works great, thanks. 120105
It was actually 2 of the trailer junction boxes. They both are working fine. Thanks.
Hazel S - 03/11/2015by: Dave M08/23/2014
Exactly what I wanted. Shipped promptly. Easy to install. 148167
Working great, just like it should.
Dave M - 08/23/2015by: Smitty07/10/2016
I just finished the installation of the boxes, so I cannot report on their durability as yet. But, I can say they functioned properly after installation and are built well. For the money, they are diffently worth the buy. Other reviews indicated terminals are mismarked and sealing grommets are low quality and do not withstand intense exposure to the elements. I sused them for just a 4 wire hookup and the markings were accurate for that. As for the grommets, I found the blanking grommets to be a temporary design and could not possibly with stand the elements for a long period of time 270363
Still working.
Smitty - 07/10/2017by: BODUNRIN.A12/03/2015
There is a saying which says that knowledge is power and seriously nothing can be more true.When I bought my trailer in 2012,I bought it brand new but unfortunately it was hardwired and for somebody like me I don't like such thing but unfortunately I never knew that there is a junction box like this that can be used for trailers to make a neat connection.One day,I was just checking for some items on etrailer when I came across this junction box and I watched the video and honestly I did not think twice to make up my mind to buy it because I know it will make a positive difference. 232969
by: Ray S.09/24/2014
Junction box makes replacement of damaged trailer cord fast & easy. 152869
Excellent
Ray S - 09/24/2015by: Steve L.07/16/2015
I wanted to get away from the wire nuts used on my trailer wiring. I bought 2 of these boxes and have installed one as a main box to distribute the connections to the trailer from the 7 pin plug. It was easy to install and had all the right hardware. You just have to add the right gauge connectors to your gauge wire and, for me, a couple of self drilling/tapping screws to mount. The second box will be for distribution of wires inside the trailer as I add 12v components. Super fast shipping on this and everything I have purchased so far, i.e. al191 marker lights. 212076
by: Austin W04/09/2017
This junction box makes it so much easier to make your connections and it just looks cleaner too. Plenty of room for multiple wire applications. 365017
by: Rick12/12/2010
Great products and service The junction box and molded trailer plug take a little extra energy to install- but the installation will be worth it, and replacements of the plug is much easier. The quality of the service from this company is Great! seldom do you find a combination of low prices, quality products and great customer service. My Order was delivered quickly and I received email advisory for each step of the process- including follow up on the delivery and they have installation videos and a great FAQ section. 4013
by: Robert C08/18/2017
Purchased a Spectro junction box for rewiring my car hauler.Never rewired a trailer before. I can't believe how easy it was. If you pay attention to the fact that the junction box does not follow your trailer light color code. I installed the junction box first, attached wires from 7 blade molded plug then attached wires to the indicated functions and ran to the taillights. Attached to hitch for ground, turned on lights and blinkers using a test light to pin point wire function and I was finished. worked great. 422337
by: Tom Drury07/07/2012
Service and response were good. The color code of the cabe did not match standard color code for trailors. I did need to use a volt meter to find left and right turn signals, running lights, and the reverse reverse signals. At this time I dont know if the problem was how the cable was made or how my truck was wired. The quality of the cable was fine. The break out box seems to work fine and I think this will be an improvement to splicing wires toteather with butt splices. The quality of the box is fine. 47029
by: Kevin L06/04/2017
I used this to connect the 4 pin coiled connector. This worked perfectly. I had five wires coming from the trailer, and this helped connect those. I drilled a hole through the back and through the trailer frame and fished the wires in through the back. This way there are no wires showing, they are fully protected inside the frame and the box, and there are no inline connectors to shake loose. The online help was just what I needed to know how to connect up the wires correctly. This was perfect! 388603
by: RJ07/15/2013
Installed as I had planned and it went well. Wired the supply line to the box to all of the correct wiring terminals as it is labeled in the box. I was prepared by other reviews, things may not match up, which they didn't, but no biggie. Once I flipped a few wires around things worked nicely. 89609
by: Mike F.04/02/2013
This product was delivered in a very short time after order was placed. It is everything that I expected. There is plenty of room in the box to run the various wires both incomming from the vehicle to trailer connecting wire harnes and out to the various lights and brake connections. I have not had a chance to install this box yet, but I definatly know that it will make the installation of the trailer wiring much more simple and relible than what I had done on my previous trailer. 73803
by: Andrew H.07/24/2017
One of my favorite discoveries here on etrailer.com. Makes it dirt simple to organize your wiring and leave room for expansion. All the screw posts are captioned with embossed labels - R. Turn, L. Turn, White (Ground), etc. Really like the cable clamps that act as strain reliefs. The only thing I can think of that could be improved on: A little drain in the bottom for water? I drill one or two 1/8-inch holes in the box to allow any water that gets inside to drain out. 410022
by: Bob H.08/20/2012
Had some real issues with this one. Should have noticed when purchasing this harnes is not wired using standard truck/trailer color format. Other than that it went together fairly nice. If the connector would come apart I was thinking of fixing the wiring my self. 52400
by: Ed B02/13/2017
Well made product with a great design. The only criticism I have of the product is the cheap flat head screws provided with it. They should be stainless and the smaller ones Phillips head. If the screws were of be it would have gotten a five star rating. 341553
by: Robert O.07/13/2016
Wiring junction box; made wiring easy; must have item. 271408
by: Elijah K11/12/2014
I would love to rate a 5 star, but the box is not the greatest to install when it requires you to go out and purchase your own mounting screws. I installed this on 2 of my trailers and it seems to do the job perfectly, I even had to replace the 7 round plug on one of the trailers and it made it really easy to redo the wiring. I would, however, recommend this to anyone looking for something to use for ease of access. Thank you etrailer. 160676
by: Jack Stout02/13/2017
I have used errailer at different times. Each time their products have been the absolute best. Their phone clerks are knowledgeable of product and service. Shipment time has always been extreamly prompt, sometimes as little as 2 days, retailer is unaware that I grew up in a fleet service shop, I owned and operated my own for 20plus years. I also have a [retail] store that uses their service, a simple ITS THE BEST is all I should say! 343776
by: Jake Bise05/26/2017
Excellent customer service! Ordering the products on line was easy and the instruction videos and installation tips were very helpful. I received my order as promised and every thing I ordered was packaged and shipped professionally. I will definitely return to etrailer for any future purchases. Also the quality of products was excellent and the price was a lot cheaper than anywhere else I shopped, even with shipping cost. 386542
by: Mike R05/11/2017
Products received were high quality as advertised and the customer service was awesome. US postal service as the delivery method was less then impressive. Found my package laying on the ground by my mailbox roadside. This by no means was Etrailers Fault but something to consider when they chose a delivery method for their customers. The experience with Etrailers other then this was awsome. Will be ordering more for sure. 380539
by: Seth07/22/2012
It was nice for organizing the wires and install. The rubber wire hole plugs are not the best. One month outside in the sun and the top one dried out and cracked. I guess install it some where it is protected from the weather. 48905
by: Chris B11/07/2016
Rewired my trailer and used this junction box to go from my main cable to all the individual lights and brakes. It worked great, the only thing I didn't like about it was that it only had two cable clamps on the inside 314692
by: Rick J.07/22/2016
Love this product. I have used this on one other trailer I have and the last one I installed on it was a 30ft flat bed trailer and used two of them. One up front and one at the back end of the trailer. Makes it much easier to connect the side lights up and all light at the rear of the trailer. All so if adding stuff later it makes it easier from either end of the trailer. Really good product and built very well. 275047
by: Jason C07/23/2015
When replacing a trailer plug with anything more than a 4flat connector this is a must have. Multiple openings and grommets make it very easy for installation and configuration. Also when figuring out mixed up colored wires on old trailers, this makes switching wires around to the correct lead super easy. Don't trust colors on old trailers! It does not come with any self taping screws or hardware. 213902
by: Russell F.11/07/2012
Solidly built and works well - definitely a time saver if there's a need to rewire anything or add a circuit in the future. Just beware - the terminals each have a label with a color and a function (e.g. "Tail", "Brown") but some of these do not match the standard 7-way wiring suggested on this site. I think "Stop" and "Red" are listed together, even though the brakes are most often "Blue". 58961
by: Dave H.01/19/2015
Purchased along with 10' of the Deka 7 wire cable. Nice box, although would be better if it had an additional wire entrance on the right side of the box. The left side has 2 entrance points, the right side has only one. Easy enough to get around by drilling a hole in the side and sealing the wires with silicone caulk. Other than that, it provides a well sealed junction point for the wiring. 170380
by: S Lewis02/06/2017
All ordered items worked great. Love the LED tail lights. Didn't have any problems fixing the trailer thanks to the many technical articles I found on etrailer. Not sure what happened with UPS shipping since I got notified that the parts had shipped on Saturday but didn't get them till Wednesday evening (paid extra for 3 day shipping), but definitely recommend ordering from etrailer. 341399
by: Everett L03/02/2017
Great fenders for what I am constructing--which is NOT a trailer. It IS a 1946 Ford Cab Over Engine (COE) truck with a flatbed. Perfect fit dimensionally. Fenders arrived in great shape even though I was skeptical. Packaged nicely. Junction boxes have been used through out truck as a water tight area to terminate wires and house relays. When done I will send pictures. 350891
by: Lonnie W.03/27/2012
I have received the Trailer Wiring Junction box but have not had the opportunity to install it yet. Prior to my purchase of this item I researched the installation video located on the etrailer site. My 16' trailer will be in use within the next month and I am looking forward to many years of good service. This is just the item I needed to repair the wiring on this trailer. 35255
by: Bob N12/05/2012
I have always ordered my trailer repair and building parts from etrailer. I currently havee 5 trailers in my business and need a source of quality repair parts. Their products are always first rate, the prices are great and the service has always been first class. This is a merchant who still belives in quality products and first rate service. Thanks'.............. 60762
by: Howard A.11/30/2016
A good box is nice not to have to direct wire everything the junction box solved that. Did learn not to tighten the mounting bolts till after everything was installed and the lid was on because tightening the bolts first the box would bow out. 4 stars instead of five is because I really don't think it would cost that much to throw in some mounting hardware. 321055
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