Black/Grey Tanks always show empty

I was wrong...tanks monitors appear to work ok. This was a learning experience. Did not believe the Black and grey tank sensors were working, but the tank was just not full enough to make the 1/3 full light turn on.

So if inquiring minds would like to know:

The 2007 Aspect 26A has a True Level tank monitoring system.
1. To access tank sensors on the black tank you have to remove the bottom of the cabinet under the bathroom sink.
2. To access sensors on the grey tank you open the outside water service compartment door.

It takes 12 gallons to fill the grey water tank to the 1/3 mark.

With the Systems monitor panel removed the test results at large white connector was as follows when you press the test switch:
Ground - Pin 3 (white wire): Neg battery terminal connection
Fresh Water - Pin 4 (red wire): Empty = 4.94 volts, 1/3 = 4.81 volts, 2/3 = 4.69 volts
Black Water - Pin 5 (brown wire): Empty = 4.94 volts
Grey Water - Pin 6 (grey wire): Empty = 4.94 volts, 1/3 = 4.80 volts

If you get these readings at Pins 4, 5, and 6 then it appears that the Mirus Detector Cells and the ground are in good condition and the red circuit board is putting out the correct voltage to the cells.

What is that saying about learning from your mistakes???? I should be really really smart by now but seem to keep finding new mistakes to learn from

Dicknellen, you are right, I do have the true level tank level indicators. Trying to trace the lines but the lines from the monitor panel go to a junction and ALL of the lines from the junction are yellow, can't find a way to differentiate which is which. Winnebago uses a LOT of yellow wire. Must be 500lbs of wire running around on the motorhome.

Tried to find the connectors on the black and grey tanks but because they are enclosed on the Aspect 26A motorhome it wasn't possible to see much. I am learning more about how this thing is put together. May have to go underneath and see if the panel on the bottom is removable. Or better said, if it is removable by me.

The empty light is always on, if the indicators are working then as the tank fills the 1/3, 2/3, full lights will also turn on. Found that the true level indicators are wired in series. 1/3 tied to 2/3, tied to Full. Downloading a wiring diagram from Winnebago and will see what I can learn from that.

ScottG wrote:
No, your right, dirty sensors will indicate there something in the tank when there isn't.
There's a broken wire someplace. Since it does it with multiple tanks I would think (hope) it's at the back of the monitor.

+1

I would also check the ground wire on the back of the indicator panel.

You have the True Level tank indicators that Winnebago started using in 2005, I have the same problem with our True Level black tank indicator. The gray and fresh water, battery condition & propane are all working as they should. My black tank indicator worked up until 4 months ago then just started showing empty. Since it is the black tank I can shine a flashlight directly into the tank by opening the toilet flush lever to see how full it is. I got underneath my Winnie and found all the tank contacts on the black tank and they all looked ok. I will be watching post on this forum to see if you get a answer. Regards, Dick

Rolin wrote:
Now if I bottomed out and put a hole in the tanks then I have infinite capacity ;-).

No, your capacity would depend on how many feet you are ASL. :B

Thanks woodglue and TKcase01 for the information on how to adjust the indicators. I will check that out and let you know what I find.

I hope this is something simple....feel really uncomfortable not knowing how much we have in those tanks. Don't want any surprises.

Now if I bottomed out and put a hole in the tanks then I have infinite capacity ;-).

hotbyte wrote:
I think typical issue is dirty sensor makes them read a false high, not empty, as noted in links above. I've not really looked into how they work but would assume the liquid in tanks completes a circuit between the bottom sensor and ones going up tank??? Maybe that bottom wire is loose on the tanks keeping circuit open.

Or,maybe a you bottomed out and put big holes in tanks :) :) :)

No, your right, dirty sensors will indicate there something in the tank when there isn't.
There's a broken wire someplace. Since it does it with multiple tanks I would think (hope) it's at the back of the monitor.

Here is an informative video on how to adjust your tanks:

Adjust Your Tank Sensors

WoodGlue

I think typical issue is dirty sensor makes them read a false high, not empty, as noted in links above. I've not really looked into how they work but would assume the liquid in tanks completes a circuit between the bottom sensor and ones going up tank??? Maybe that bottom wire is loose on the tanks keeping circuit open.

Or,maybe a you bottomed out and put big holes in tanks :) :) :)