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marpel
notapplicable
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Joined: 07/04/2013
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Due to a bit of age/corrosion, I have decided to replace the 7 pin plug/cable on the trailer.
As I usually do when I am about to tackle something I haven't previously dealt with, I searched the net and YouTube for tutorials/instructions just to make sure I don't miss anything.
The funny thing was, out of all the vids/articles I reviewed, only one could be found that touched on replacing the entire cable (ie wiring directly into the junction box).
Every other one described how to either replace the plug (by cutting the old plug off) or cutting/splicing the cable farther up. In fact, in one video, the fellow showed the old cable, and existing junction box, then proceeded to cut the old cable halfway, and splice in a few feet of the new cable and plug using another junction box to connect the new and old cables, then fastening the new junction box right next to the existing junction box (with the old cable running from one box to the other).
To me it seems simpler to remove the entire old cable, get a new cable and run it right to the existing junction box. Or am I missing something??
Marv
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Fisherman
Angus, Ontario, Canada
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Maybe the new cable was too short for his application. More contacts and breaks, more corrosion possibilities and breakdowns. I would go with one junction box.
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BB_TX
McKinney, Texas
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I managed to pinch my cord between the hitch and king pin. Bought a new one at a local trailer shop and installed it myself. They had different lengths available. Really pretty simple. Open the junction box and look closely at the existing wires. Maybe even tag and/ or take a picture of them to make sure you get them back correctly as you may have some where two or three wires connect together to the new cord. That way there will be no second guessing about what goes where. But again, nothing to really worry about.
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Gdetrailer
PA
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Joined: 01/05/2007
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Fisherman wrote:Maybe the new cable was too short for his application. More contacts and breaks, more corrosion possibilities and breakdowns. I would go with one junction box.
X2!
Most likely the person in the video was not able to get a cable long enough so splicing somewhere else would be needed.
Not ideal but could work in a pinch.
As someone else mentioned, they do sell prewired/molded cables with plugs in different lengths and even different wire ga sizes. You can also buy bulk wire for 7 pin harness to customize your cable to the length you need and then add a replacement plug to that.
Much better however to get a cable long enough or even a bit longer in the first place and go back into the original junction block. Otherwise you are adding an additional point of failure with an additional splice.
Extra junctions or splices can eventually come back to bite you in the behind and that typically happens at the worst possible time..
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Dusty R
Charlotte Michigan 48813
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I would use crimp butt splicers and Heat Shrink insulation tubbing.
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Gdetrailer
PA
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Dusty R wrote:I would use crimp butt splicers and Heat Shrink insulation tubbing.
![[emoticon]](http://www.rv.net/sharedcontent/cfb/images/rolleyes.gif "rolleyes")
Rookie mistake.
Crimps work best with proper quality crimping tool, very few people have the proper crimping tool and substitute pliers and crush the connection making a very poor and unreliable connection.
Additionally, standard heatshrink tubing is not weather proof or water tight and moisture will destroy the connections hidden inside the tubing.
Not to mention the average backyard electrician won't have a good heat gun and will use matches or a lighter to shrink the tubing making a mess of the job..
For heatshrink tubing to work in the outdoors you must get adheasive lined tubing, it has a heat activated glue that surrounds and seals around the wire insulation making a good water and weather tight seal..
But, a good electrician will try to avoid allowing connections to be exposed to weather which means taking the connections back to the original connection box which is protected from the weather.
Inside that box, the connections are made with wire nuts, no need to reinvent the wheel. Just use the existing wire nuts inside that box and all will be fine.
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marpel
notapplicable
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Thanks for all the replies:
Just to clarify though, the new cable was not too short as the new box was placed right beside the old box, so the, loosely strung, replacement cable appeared able to reach the old box quite easily.
And BB_TX, your description was exactly what I was planning on doing. Take photos or label current box layout and just repeat with new cable. Logically seemed pretty straightforward.
Just figured, because no-one seemed to want to tackle the junction box connection in any of the vids/tutes, that I was missing something that made it difficult.
Marv
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Grit dog
Black Diamond, WA
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Joined: 05/06/2013
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No, you’re tracking right. Replace the cable back to the j box if you need to.
If no issue with the cable though, no reason to not just replace the plug if it has issues or serious corrosion.
Fwiw, I’ve not had good luck with the pre-wired molded Plug pigtails. Have another one I installed a couple years ago that is shorting out somewhere in the molded together plug.
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Dusty R
Charlotte Michigan 48813
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Gdetrailer wrote:Dusty R wrote:I would use crimp butt splicers and Heat Shrink insulation tubbing.
Rookie mistake.
Crimps work best with proper quality crimping tool, very few people have the proper crimping tool and substitute pliers and crush the connection making a very poor and unreliable connection.
Additionally, standard heatshrink tubing is not weather proof or water tight and moisture will destroy the connections hidden inside the tubing.
Not to mention the average backyard electrician won't have a good heat gun and will use matches or a lighter to shrink the tubing making a mess of the job..
For heatshrink tubing to work in the outdoors you must get adheasive lined tubing, it has a heat activated glue that surrounds and seals around the wire insulation making a good water and weather tight seal..
But, a good electrician will try to avoid allowing connections to be exposed to weather which means taking the connections back to the original connection box which is protected from the weather.
Inside that box, the connections are made with wire nuts, no need to reinvent the wheel. Just use the existing wire nuts inside that box and all will be fine.
True, but I do have the proper tool. I'm a retired construction electrician. And if I remember right, a box is required when the voltage is above 35 volts. On a trailer a box collects road salt and rusts.
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BurbMan
Indianapolis, IN
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Joined: 09/20/2001
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I just replaced the cord on my 5er for the same reasons. My initial thought was just to replace the plug, but since the plug is out in the weather, I would rather have a molded connection there, so I replaced the whole cord.
First measure your existing cord and get one the the same length. I got this cord from Amazon that comes in 8', 12', and 16' lengths. If your size is in between you can always shorten the cord.
The cord typically terminates in a standard 4" steel j-box. On my 5er, the box is under the pin box, and even though it's open to the elements on the bottom, it's well enough protected that the screws on the cover and cable clamp weren't rusted to death.
On my TT, the box was on the frame up under the Coroplast underbelly material, keeping it dry and protected from the elements.
It makes zero sense to add a second j-box on this cord unless the factory put the original j-box in a location that is impossible to get to. Otherwise, it's just a matter of opening the box, matching the colors, and connecting the new cord. Pay attention to the colors used on the trailer side and also how the breakaway switch is wired in. As you know in residential wiring black is hot and white is neutral, and in auto wiring red is hot and black is ground. Some trailer mfrs follow the black/white convention for 12v wiring, some follow the black/red, so pay attention to how yours is wired.
Typical 7-pin cord will have 2 #10 black/white wires for (+) and (-) charging lines, a #12 blue wire for the brakes, and 4 #16 wires for the lights. As Grit Dog says, the factory uses wire nuts and they work just fine.
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