15 Vista 35F black&grey water level issue

Digger29 · 07-21-2015, 02:27 PM

So we took her out again this weekend and we had a blast in her. Quick question, both the grey & black levels are saying they're empty and we clearly know that's not the case because we used 3/4 of the water this weekend. I called our dealer and he can't look at it until August 7th. Anything I can do or check in the meantime? Every question I've asked on here you guys have known the answer to and we both appreciate the help. Thanks again, Mike & Yolanda

Clay L · 07-21-2015, 02:46 PM

In 2005 Winnebago went standard with the TrueLevel Tank level display system which uses sensors on the outside of the tank so ignore what people say about the old style through wall systems. It sounds like the wires from the black and gray tank sensor block strings are open. I would check the connectors behind the OnePlace center.

Here is a general description about how the system works.

There are three small black square sensors glued the side of the tank with a wire running between each sensor. A wire from the top sensor goes back to the display board. It supplies 12 volts from a resistor on the display board to the string of sensors. There is a wire from the bottom sensor going back to the display board ground.

The sensors are active devices - that is they contain an integrated circuit.
When the fluid reaches each one it - in effect - acts as a switch and closes when the fluid is there and opens when it isn't.
A LM339 Low Power Low Offset Voltage Quad Comparator IC on the display board senses the voltage change and turns an LED on the display board on or off .
Note that the board really doesn't know which of the three sensors is involved since they are in series. For example if the level is rising it turns on the 1/3 full sensor when any sensor closes. When another one closes it turns on the 2/3 full LED and so forth. This works well when all of the sensors are good but if one sensor fails open the display board will show 2/3 even when the tank is full. Conversely if any sensor fails closed the 1/3 LED will be lit when the tank is empty.

SuperGewl · 07-21-2015, 11:56 PM

You have 2 Black tanks, What does the other Blank tank indicate? It is possible to have split the water enough to still have no indication on all 3 tanks. To test the blank tank levels add about 10 -15 gallons to the forward black tank. It's best to do this via the 5 gallon bucket method. Do the same to the other black tank and the gray tank, then check to see if the levels indicate.
I know for a fact that the rear Black tank seams to take forever to get an indication due to it's size and shape. The front Black tank does not take but a few uses to get an indication due to it's size.

If you don't feel comfortable about doing this then dump the tanks and see if anything comes out. Then perform the test while at the dump station.

Digger29 · 07-22-2015, 06:32 AM

Will definitely be trying that this morning. When we used it 2 wks ago on a 3 day weekend trip the levels were both showing about half full when we got home and after roughly the same 3 day trip and they're both showing empty.

99Adven · 07-22-2015, 02:23 PM

We have a 15 35F. All the previous posts are really good. Well, I heard through the grapevine, our local dealer tech, that the tanks need to be kept squeaky clean for the indicators to work right. So we use a plastic clear 45 degree angle from the outlets to our hose so we can see what is coming out. We keep washing and pushing water through the toilets and sinks until the water is as clear as the water going in. Yes, it's a lot of extra work..... I also then add water and a good dose of dawn dish soap to each of the tanks to slop around while I drive down the road. I've heard ice cubes will clean the sides too but haven't experienced that method to date. So far no problems but am holding my breath and knock on wood constantly. I don't know if this is your problem but thought I'd through my 2 cents in.

oakcreekeric · 07-22-2015, 02:39 PM

I'm going to throw this out there, seeing as no one has..

Q - Did you use both toilets?

Only reason I ask, most times we do quick weekend outings, we just use the rear one.. we don't even bother to prime up the front one...

I'm going on the assumption you know there is a toggle switch above your indicator levels that switches between the two tanks... only reason I say this is.. if you didn't use the front toilet, but the indicator switch is reading the front.. then obviously the levels are going to be "empty"..

Again.. I'm assuming you know about the switch and you have it switched to the correct tank you are trying to read..

SuperGewl · 07-22-2015, 05:16 PM

Using a clear elbow in the Dump station is a must.

Also using the Flush out connections make a big difference. As stated by 99Adven, you need wash them good and keep some water in them, 2-3 bowls full, post dumping them. On the front tank it is important to really flush enough water through it, do a visual check down the toilet to make sure you see WHITE in the bottom.
Ice in the tank is great for cleaning while driving down the road and does work.