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BiggyJ's avatar
BiggyJ
Explorer
Oct 21, 2018

Rv 12v grounding question

Hi everyone,

I'm hooking up a new A/C, thermostat and control box for my live in travel trailer.

Really different from everything else I have worked on. It's a Dometic system and they
have there own way everything is done. Have to use their t-stat and control box.

Where I need your help:
I took the schematic and drew out a wiring diagram where I could understand it and uploaded
it, then sent the link to the head tech where I bought everything and asked him to look at it.

Here is that link:
http://jaxehost.com/or/for-lynn.jpg

And here is his reply:
"I have looked at this and you have to connect a 12v ground signal to the wire on the number 2 connection . The control box will not send the ground out to the t-stat.
Thank you"

So... as you can see from my diagram, I just show a normal -12v lead. He is saying something about 12v ground.

What does he mean that is different than what I have drawn?

Thank you kindly for you expert help,
John
  • I think you confused him by calling ground, -12v. He's saying your diagram is correct.
  • I think drsteve is probably right in the confusion issue. There is no -12 vdc. It is 12v ground, or just ground. There are actual power systems that do have a + voltage and a - voltage (meaning below ground level), but not in an RV.
  • Your schematic shows -12V travelling between the two devices but no additional connection to ground. You need to connect a ground wire somewhere in the 12V circuit. You have the 12V constant power drawn but no lead to the trailer 12V ground.
  • Thank yoy guys.

    I wired it just like my diagram and it works fine.

    PS - I'm just used to working on 12 volt auto systems and electronic circuits so I expected if he ment a connection to the frame, he would just say chassis ground. Just through me a bit.

    Thanks again for the replies. All is well :)

    John