MICTUNING Heavy Duty 7 Gang Junction Box Install Help

[Yoda]

Howard,

Fifth wheels do not have all of those grounds at the junction box. The break away switch does get its power and ground from the junction box, located right beside the break away under the pin box. All of the grounds that travel trailers have connected are inside the front storage of a fifth wheel, along with the self resetting breakers, so there is no large amount of grounds in the junction box. I think that is all, maybe.

This is why I say stick to travel trailer wiring and only pay attention to pictures posted from a travel trailer so one does not get confused.

Brian

howson

Brian - not to disagree, but of you look at the picture in post#20 of my king pin junction box there are a whole bunch of negative return wires in the blue nut. These are the returns for the trailer running, stop, turn, brake, etc


I copied it here for convenience. This is inside the back of the king pin box. White negative returns are in the blue wire nut

There is a second bunch or negative return wires in the front bay below the master power bar with the resetting breakers. These are all the internal trailer 12v negative return circuit wires.


Second group of negative return wires in a 5th wheel.. This is in the front bay left corner. It may be hard to see as in my case it was buried in the foam blob. The wire nut was loose when I uncovered it.. One wire ran from the blue nut to a frame ground.

I hope this helps clarify how the negative return wires are on a 5th wheel - at least my 220RK are

I actually think it is a plus to have all of the negative wire home runs back to theses two locations.

Hope this helps
Keith

[ncitro]

So I went out and pulled the cover off the Mictuning box. There are indeed 5 wires on the post for one of the connections. And there is plenty of thread left.


The other day I made a leap. Cut the cord:



I now have a short true whip cord with the same end. The plug is installed on the cross member of the pin box, the whip cord plugs into the truck and the connector on the trailer. No more wrapping the cord and shoving it in the pin box. Long term I plan on getting a coiled cord to make the connection.

Oh I like that. I also have my Ford TPMS cable and Anderson cable for my DC to DC, so I guess I would have those anyway, but I love the idea.

[howson]

Yoda

Not sure where we disagree. -12v returns (eventually) end up at the battery. That the physical wires may be in a different place in different models of GD trailers is no surprise.

If 5vrs do not use the frame (at all) as a return path? That would be a surprise to me and proof yet again that I am still learning constantly.

I find Jlawles2 picture of the multiple -12v return wires interesting in the Mictuning box. The Bargman cable will have one, and the output to the trailer is usually one. Since I think the Bargman cable ("7 pin") is to the left in the picture, makes me wonder what the other three -12v returns are for in the box going to the trailer.

Regardless, whether the -12v returns are ganged in the Mictuning or ganged outside the box on a distribution block, electrically they all provide a path back to the negative side of the battery.

Sorry if I confused the conversation.

[JBill9694]

I can't find it now, but somewhere I read that the RV industry decided to treat the -12 VDC, or "ground", the same as residential ground. That is to run all the DC grounds back to a common point or points instead of grounding to the frame throughout the trailer. Hope this is clear, I have slept since I read about the grounding. Anyways, that is way there are so many DC grounds at the junction box instead of just one to connect the truck to the trailer frame.

[Yoda]

Yoda

Not sure where we disagree. -12v returns (eventually) end up at the battery. That the physical wires may be in a different place in different models of GD trailers is no surprise.

If 5vrs do not use the frame (at all) as a return path? That would be a surprise to me and proof yet again that I am still learning constantly.

I find Jlawles2 picture of the multiple -12v return wires interesting in the Mictuning box. The Bargman cable will have one, and the output to the trailer is usually one. Since I think the Bargman cable ("7 pin") is to the left in the picture, makes me wonder what the other three -12v returns are for in the box going to the trailer.

Regardless, whether the -12v returns are ganged in the Mictuning or ganged outside the box on a distribution block, electrically they all provide a path back to the negative side of the battery.

Sorry if I confused the conversation.

I believe this is a great thread and hopefully this will help with the confusion of what the white wire bundles under the blue nuts are and the extra white wires at the king pin box.. Now remember this is for my 5th wheel. Now for my 220RK 5th wheel I have found at least 2 frame grounds for the 12V negative return white wires.


This connection is located below the distribution panel. It has the 120V ground wire (bare copper) and the white wire is from the negative side of the 12v circuits. Second photo is of the distribution box. Top right white wire goes to the frame (first picture) via a secondary 12V negative bus bar located on the floor behind the distribution panel., The black wire is solar negative. Third white wire I have not traced yet., but believe it runs fully forward to the king pin box. I will be verifying this. Bottom corner is the positive block. Black wire is Positive from the distribution switch. Red wire is positive from solar. I have since moved the solar connections to the front bay (ran new wires forward from roof.).


This is the negative bus bar located behind my distribution panel. The big white wire on the left is from the distribution panel and the big white wire right goes to the frame. The rest are from interior -12V circuits.. BTW if folks are having flickering lights, look for the bar (behind false wall) I found several of the connections loose.


Second frame ground I found was in the front bay under the positive bus bar. The black wire is from the original battery, The white wire is from the white blue nut bundle (buried behind red positive from battery to disconnect switch) for more of the interior 12v circuits

Now as to Neils ncitro picture the extra whit wires are the negative returns for the running lights, stop and turn and brake like I found on my unit . On my unit I have the same wires tied to the blue nut,. I checked the continuity with the positive side (running lights, brake, turn, etc) using my multi meter. Now in Neils box picture notice a red sheath wire coming in. That is the brake wiring. It has a blue (positive) and white (negative) wire. That white negative wire is one of those tied to the post.

Humbly submitted and hope it helps clear things up on a 5th wheel. - or did I increase the fog factor? Sorry if I did

Keith

[ncitro]

Yoda Just to clarify those pictures are not mine, I was replying to Josephs post.

[Jlawles2]

Yoda

Not sure where we disagree. -12v returns (eventually) end up at the battery. That the physical wires may be in a different place in different models of GD trailers is no surprise.

If 5vrs do not use the frame (at all) as a return path? That would be a surprise to me and proof yet again that I am still learning constantly.

I find Jlawles2 picture of the multiple -12v return wires interesting in the Mictuning box. The Bargman cable will have one, and the output to the trailer is usually one. Since I think the Bargman cable ("7 pin") is to the left in the picture, makes me wonder what the other three -12v returns are for in the box going to the trailer.

Regardless, whether the -12v returns are ganged in the Mictuning or ganged outside the box on a distribution block, electrically they all provide a path back to the negative side of the battery.

Sorry if I confused the conversation.

Howard,

IIRC 1 white wire is the Whip cord, 1 is all lighting (since the wiring all originates here), 1 was actually tied back to the common frame point near the battery, and the other 2 are for who knows. There could be a wire for the brakes (since that is a dual run) and a second negative putting one negative down each side of the trailer for lighting. Although one of the grounds may be for the upper marker lights.

I think Keith labeled most of them the same way.

Truthfully I did not try to figure out the mess , just make it look less like it came out of a blender and more like something that was planned all while ending up with connections that are easily trace and repairable.

The frame is partially used as a return path if I am remembering it correctly. With the modern trailers the materials are such good insulators that it makes it hard to get a good ground path up into the coach.

[howson]

..just make it look less like it came out of a blender...

So true! Got a good chuckle from that description.

[Scott'n'Wendy]

Had a brain fart when de-coupling testerday after our three week fishing trip. Left the 7 pin cable attached to the truck....

Sooo...now that the wires are ripped out of the 4" box..might as well order up the mictuning box now

[Jlawles2]

Had a brain fart when de-coupling testerday after our three week fishing trip. Left the 7 pin cable attached to the truck....

Sooo...now that the wires are ripped out of the 4" box..might as well order up the mictuning box now

This is also why I put in a second 7 way on the camper and double ended the whip cord.

[Scott'n'Wendy]

This is also why I put in a second 7 way on the camper and double ended the whip cord.

You have left it connected yourself? or expect you might?

[Jlawles2]

You have left it connected yourself? or expect you might?

I plead the 5th on that one. There may have been a lot of 4 letter descriptions going on due to the idiot that setup our slider not greasing the important areas and over tightening a few critical bolts that are not supposed to be impact tight.

[Scott'n'Wendy]

Yoda
Just a suggestion. I did the swap to the mic mictuning box yesterday, about a 30 minute job. But, for your group of 7 white wires, you could remove the yellow wire from its stud and tape it up. Its not used. Then wire in a jumper from the white post to the yellow post, then use both terminals for terminating your white wires. Food for thought.

[howson]

Yoda
Just a suggestion. I did the swap to the mic mictuning box yesterday, about a 30 minute job. But, for your group of 7 white wires, you could remove the yellow wire from its stud and tape it up. Its not used. Then wire in a jumper from the white post to the yellow post, then use both terminals for terminating your white wires. Food for thought.

Keith installed backup lights, so he may be using that yellow wire? It's been awhile, but this thread has info (I didn't read the whole thing): https://gdrvowners.com/forum/operati...lights-install

Good idea, though, for most of use about using both posts!

Howard

[Jlawles2]

Scott'n'Wendy Scott as shown in post 30, the single stud for the whites is not that full. I did if you notice alternate directions on the terminals so that one was down, one up, then the other side one down, one up, and back to the first.

Alternating the terminals helps to minimize the stacking effect. If one were to get desperate, an additional nut and washer could be used to add height to the stack, along with an all thread connector like https://www.amazon.com/Hard-Find-Fas...s%2C133&sr=1-9 then use a short screw for the last couple of wires.