Control Panel says water tank full

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Foxy61

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Oct 16, 2021
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Ontario
Just brought our new Jayco 212QB home after a one night trip to practice set up and take down.
I emptied the fresh water tank via the low point drain when we left, but the control panel says the tank is still full. I tried turning the pump on and running the kitchen faucet…a slow trickle came out, panel said water tank is still full.
Any help would be appreciated.
 

DonTom

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Apr 21, 2005
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Auburn, CA or Reno, NV
panel said water tank is still full.
Mine did the opposite. Said it was empty when it was full when I first bought the RV used. But it was like that since new. I mean my Y2K old RV.

In my case, the wire sensors in the fresh water tank were installed with the insulation still on the sensor wires. Installed that way from the factory. Those wires need to be bare to conduct. I removed the insulation and it's been fine ever since.

Anyway, if yours works like mine, it would be very unusual for it to show full when empty on the fresh water.

But a good place to start will be find your fresh water tank and look at the sensors that are in the tank and see if the sensor wires look okay. You could find something that is obviously wrong just by looking.

-Don- Reno, NV
 

John From Detroit

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Apr 12, 2005
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25,407
Location
Davison Michigan
Do not trust the lights. They are generally wrong.

Find the forum directions on sanatization of the tank and do it twice this is my FIRST suggestion After that you need tools basic instrucitons

Mix water and standard chlorine bleach 1/4 cup bleach to 5 gallons and fill tank.
How I did it. I filled tank about half then added the bleach and finished filling. There are multiple ways to do this. Would not hurt to drive a bit with the tank like 3/4 full (Drain a bit then drive) but not needed.

Drain and in your case do it again This time pump through all ines. Flush toilet shower Inside and out) water heater and so on.> Drain everything you can drain.

Check lights. If it shows empty fill again with water and about half a cup to one cup (Depending on tank size) of baking soda, Dissolve the soda in HOT water than mic with cold and add to tank fill tank and again flush lines as before... If you have it litmis paper or a pool PH test will detect when the soda has purged the lines else just keep pumping till you are sure. You can also taste the water (just a drop) Bleach is yucky baking soda not so much.. In "Drop" amounts neither will bother you.

FInally drain and fill with fresh.

How the sensors work.....
Imagina a nai or screw run through the wall of teh tank.. THAT literally IS the sensor nothing more.
The wire hooks to it. the bottom sensor is "Ground"

Each sensor other than the top and bottom hooks to a resistor network so (this is a 4 sensor diagram)

Panel-----Full==/\/\/\---2/3----\/\/\/--1/3 Common---Ground

/\/\/\ and \/\/\/ are resistors of different values

IF the panel sees "Open circuit" below 1/3 (empty)
If it sees high resistance 1/3-2/3
If it sees low resistance 2/3 to full
If it sees a short FULL

If the senors are damp be it from residual eater or algae (Hence the sanitization suggestion) Then the panel will "See" them.

Black and gray.. Work once, never again unless you power clean the tanks.. I've had... Limited success with that (I think in 15 years I got black to read empty twice after first use)
 

ChasA

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Mar 21, 2009
Posts
2,325
I suspect you have a drain valve for your water tank somewhere. You said this is a new RV. As such, there should be an owner's manual. Have you read it?
 

Rene T

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May 20, 2011
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18,418
Location
Farmington NH
You said you drained the low point drain. Now most rv’s have low point drains to drain the water lines in the RV. They are usually side my side and one may be red for hot water snd the other would be blue for cold water. Or they may have a colored stripe on the side of the pipe. Besides those, there is typically a drain just for the water tank. Did you possibly open the 2 low point drains and not the tank drain? The tank may still be full.
If nothing works, call the dealer. They may be able to answer your question over the phone
 

DonTom

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Apr 21, 2005
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Location
Auburn, CA or Reno, NV
Do not trust the lights. They are generally wrong.
I find mine to be right on the nose. I trust them to be accurate ever since I took the insulation off the wire sensors. Mine works by measuring the resistance of the water at different points of the fresh water tank. Since that water is clean, it should be accurate.

My Gray tank sensors are also accurate.

Black water tank is the only one that I ignore on my Y2K RV.

-Don-
 
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