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dkchaffee

How to diagnose OPEN GND message

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Pulled 2017 fleetwood bounder out of storage and recharged and reconnected batteries.   There was a fault showing on the command center with "OPEN GND" which I assume is that somewhere a ground wire is not connected.  This is preventing any lighting even when running from shore power from coming on.  I verified all by battery connections were as they were before storage (labeled lines, took picture prior to removal), but I am not sure where to begin looking.  Any help/guidance would be appreciated. 

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24 minutes ago, dkchaffee said:

Pulled 2017 fleetwood bounder out of storage and recharged and reconnected batteries.   There was a fault showing on the command center with "OPEN GND" which I assume is that somewhere a ground wire is not connected.  This is preventing any lighting even when running from shore power from coming on.  I verified all by battery connections were as they were before storage (labeled lines, took picture prior to removal), but I am not sure where to begin looking.  Any help/guidance would be appreciated. 

Welcome to the FMCA Forum !

Could you post the Model coach you have? and the model and make of the Command Center.

Need to know is your Coach is a Gas or Diesel powered unit.

I have a feeling you missed a cable some where. There are more then one cable on more then one  Connection and it is easy for one to drop out of sight when removing the cable from there connections.

You mentioned pictures in your original post, could you attach them to your next post?

Rich

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Assuming this open ground warning is on the 120v system. Check to be sure that the ground connections are solid between the inverter and the chassis, the ATS and the chassis, and the shore power cord and the chassis. Even if you put everything back in the exact same place, a bit of corrosion or grim on the mating surface may be enough interference to prevent the system from working.

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I did find a wire that had gotten shoved  up into the compartment and connected and it appears to have solved that.  I was cycling back through the fault messages and do see older faults for open ground so will do as suggested.  It has a Surge Guard RV Power monitor and a Precision Control Central monitor and an electrical novice and probably need to do some more education on the different monitors on the panel and what they are telling me.  

 

Thanks 

It is a gas Bounder 35P.  

IMG_0065.jpg

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Bad/faulty/weak ground connections seem to account for a great percentage of problems in an RV. Any time I'm working on mine I try to examine any ground connections in the area. If I have access and any reason to suspect them, I'll pull the bolt or screw and check it out. Sometimes a few swipes with a piece of 400 grit wet/dry sandpaper is enough to show shiny metal and get a solid connection. Then a quick spray of battery terminal protection and good for a while more.

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FWIW over 80% of all 12V problems are the result of a poor/missing ground.

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34 minutes ago, rayin said:

FWIW over 80% of all 12V problems are the result of a poor/missing ground.

Yes and most lighting in every coach that I know of is 12 Volt. And PLEASE do not ever tie the ground or neutral from an AC power source to the chassis of an RV, it could lead to a shocking experience.

Edited by kaypsmith

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5 hours ago, kaypsmith said:

Yes and most lighting in every coach that I know of is 12 Volt. And PLEASE do not ever tie the ground or neutral from an AC power source to the chassis of an RV, it could lead to a shocking experience.

It's odd you mentioned that, I just ran across this article from a supposed "expert" with RVtravel that is completely wrong IMO. https://www.rvtravel.com/diy-safe-way-to-test-the-ground-wire-bond-to-the-rv-frame/

Here is an article by a staff writer pretending to know of which he speaks; guess he never studied electrical theory.:https://www.reference.com/science/negative-ground-electrical-system-c4985d1ab3eab6c

Edited by rayin

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Wow, all these negative thoughts (pun intended):rolleyes:

Does anyone remember a car many years ago that had a positive ground system? I believe it was maybe a Studebaker. (an yes I am old)

Herman 

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The NUT in the first point of reference doesn't have a clue. The writer in the second is absolutely correct, he is speaking in reference to the DC circuit, it's a shame that he even mentioned AC except he does not tell of grounding the AC to the frame of the RV, and does not point out not to do so. If the AC ground is bonded to ground and or neutral, then if you should touch the frame or anything that connects to the chassis, and you are on ground (or heaven forbid) standing in a puddle of water, your lights will go off. The RV AC circuit is bonded at the campground main source of electrical supply. Yes Herman, I am being negative in hopes that someone doesn't accidently do this and have a SHOCKING experience. I do remember some autos and lots of agricultural machines (tractors and the like) using positive grounds. Many over the road tractors in years gone by used 24 volts to start the big engines, positive from the secondary battery was to vehicle chassis and negative from primary battery was set to chassis and used a 24 volt generator back in those days. Many of the mechanics in those complained of being shocked by 24 volts while lying on the damp ground making repairs. Studebaker had many backwards ideas, but they were 20 years more advanced in looks and engineering than most, that's why they moved south of the border in 1963, LOL.🤤 The only car car that I would buy and restore is a 61-63 GT Hawk, IMHO the prettiest auto ever built.

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I have worked on many positive vehicles. Most of them were GM and/or Ford. those can be very confusing to anyone that has not seen them before. My neighbor thought someone wired the battery (6 volt) backwards. that cost him a bundle.

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17 hours ago, hermanmullins said:

Wow, all these negative thoughts (pun intended):rolleyes:

Does anyone remember a car many years ago that had a positive ground system? I believe it was maybe a Studebaker. (an yes I am old)

Herman 

I have one -1932 Chevrolet Confederate BA 2 dr, sedan. My previous Harry Ferguson TO30 tractor was 6V pos ground too. What is more elusive was the reasoning for positive ground. I remember, do you?

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23 minutes ago, rayin said:

What is more elusive was the reasoning for positive ground. I remember, do you?

Positive voltage on copper wire caused corrosion on the copper, negative voltage does not. Sure glad the OP found the problem, and has learned a little about electricity from this post.

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53 minutes ago, kaypsmith said:

Positive voltage on copper wire caused corrosion on the copper, negative voltage does not. Sure glad the OP found the problem, and has learned a little about electricity from this post.

The reason for the corrosion is DC electrrons flow  from negative to positive.The original thinking was positive ground reinforced the vehicle frame, negative ground weakened the frame. Same basic reasoning.(corrosion) How things change over time.

That process is the basis for electrroplating; ie: transfer metal from negatively-charged anode( plating material) to positivly-charged cathode.(material being plated)

I don't think I've discussed electrical theory much since college, kinda makes my head hurt today.

 

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On 4/21/2021 at 8:10 PM, hermanmullins said:

Wow, all these negative thoughts (pun intended):rolleyes:

Does anyone remember a car many years ago that had a positive ground system? I believe it was maybe a Studebaker. (an yes I am old)

Herman 

Several of the British cars had positive ground.  I owned an Austin Healey with positive ground.   Took some engineering to make a negative ground shortwave radio work in it.

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On 4/22/2021 at 12:50 PM, rayin said:

I have one -1932 Chevrolet Confederate BA 2 dr, sedan. My previous Harry Ferguson TO30 tractor was 6V pos ground too. What is more elusive was the reasoning for positive ground. I remember, do you?

I think if you go far enough back, most cars had positive ground.  I'ved no idea why.  And yes, earlier Studebakers had positive ground.  I think that went away before they changed from 6 to 12 volt sometime in the early 50s.  My mother's '52 had six, my father's 56 had 12.  Oops.  Sidetracked into my Studebaker infatuation.  

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