Fresh Water Sensors

[greg1406]

Hi We have a 2007 Adventurer 35A, when I press the button on the monitor panel the fresh water tank shows full even though the tank is empty. I can see the tank is empty and I also see the sensors on the side that are all attached to the tank.

What is the best solution to repair this?

Thanks,
Greg

[SuperGewl]

It sounds like you have a ground problem. You need verify the indicator system is good and them verify the level sensors are working correctly.


With the tank partially filled with water does it indicate correctly? If so when (at what level)does it start to indicate correctly?

Also is this the type of system that has wires attached to post in the tank or the type with the sensors on outside of the tank?

Pictures work well also.

[nothermark]

You probably have either slime or scale inside the water tank shorting across the sensors. I'd start with a Clorox and water cleaning. If that does not do it try removing the wire from one of the probes and see if the LED changes. An open is empty. If the disconnected probe reads correctly the answer is a an acid like limeaway then rinse the tank. If the disconnected probe does not read correctly the problem is the control board.

[greg1406]

Originally Posted by SuperGewl

It sounds like you have a ground problem. You need verify the indicator system is good and them verify the level sensors are working correctly.


With the tank partially filled with water does it indicate correctly? If so when (at what level)does it start to indicate correctly?

Also is this the type of system that has wires attached to post in the tank or the type with the sensors on outside of the tank?

Pictures work well also.

The sensors show full even when I have half a tank of water. They are the type that stick on the side of the fresh water tank.

All my other tank sensors work correctly.

[Clay L]

Originally Posted by nothermark

You probably have either slime or scale inside the water tank shorting across the sensors. I'd start with a Clorox and water cleaning. If that does not do it try removing the wire from one of the probes and see if the LED changes. An open is empty. If the disconnected probe reads correctly the answer is a an acid like limeaway then rinse the tank. If the disconnected probe does not read correctly the problem is the control board.

Winnebago went standard wit the TrueLevel system in 2005. The sensors are on the outside of the tank and can't be shorted by slime. They can be fooled if enough crud builds up on the inside of the tank however.
I have heard of it happening on the black and gray tanks but never the fresh water tank. Could happen I guess if enough algae grew in it.

[Clay L]

Originally Posted by greg1406

Hi We have a 2007 Adventurer 35A, when I press the button on the monitor panel the fresh water tank shows full even though the tank is empty. I can see the tank is empty and I also see the sensors on the side that are all attached to the tank.

What is the best solution to repair this?

Thanks,
Greg

That sounds like it may be a control/display board problem. Mine was behind the OnePlace center display panel. Below is a general description of how the system works. I think all of the sensors would have to fail closed for the tank to show full - possible but not probable.

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 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.

[ernieh]

My guess is that you have either a ground or board problem, but here's something else that you might check. On my previous coach (Winnebago) a bad fluorescent light would cause the TruLevel system to always read full and not allow the fan to turn off when using the heat pump.


Turn off all lights, chargers, TV's, etc. and see if the problem still exists.

[RLBCCB]

This happened to me and turned out to be a roll of paper towels up against the sensors. There is some area beside the fresh water tank that I had stuck the towels in and it caused the sensors to read. After I removed the towels the sensors went back to reading correctly.


Sent from my iPhone6 using iRV2 mobile

[greg1406]

Originally Posted by Clay L

That sounds like it may be a control/display board problem. Mine was behind the OnePlace center display panel. Below is a general description of how the system works. I think all of the sensors would have to fail closed for the tank to show full - possible but not probable.

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 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.

Thanks for the help. I ordered a new set from Winnebago one was shorted closed always showing 1/3 full with all sensors off the tank.