Fleetwood Motorhome Association, Inc. - Water Tank Level Sensors

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Water Tank Level Sensors

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05/09/2014 4:25 AM

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Message # 1550830

Deleted user

Does anyone have an electrical schematic of the sensing system used for typical OEM fresh/grey/black water tanks (and LP gas too)? My water tank readings are all erratic or inaccurate, and I was wondering just how these systems work. Some recommend replacing the tank sensing electrodes, talking about fouling and/or corrosion. Some say switch over to external tank sensors (but getting at the tanks and wiring can be formidable). But, before I (pardon) dive in, I would like to understand the problem a bit better.

05/10/2014 1:04 PM

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Reply # 1551380 on 1550830

Deleted user

We have a '99 Bounder 34J. It uses electrical probes in the tanks that, in essence, measure the electrical resistance of the medium inside the tanks: water. If water is touching the probes the resistance is lower; if not, the resistance is higher. Anything that "sticks" to the probes (e.g. toilet paper) will cause an incorrect reading. I have never been pleased with the performance of this system. In fact, since the fresh- and gray-water tanks are semi-translucent, I usually open up the basement doors and take a look if I really want to know what's going on.

I reverse-engineered the display panel and have created an electrical schematic. It may contain errors (your mileage may vary), but I would be happy to send it to you. I would post it here, except I don't see a way to post an attachment. If you would like to have it, please post an email address and your preferred file format (jpeg, tiff, pdf, etc.). The native file format is CADSoft Eagle.

Regards, EdC, ARS AF7BC

05/10/2014 1:26 PM

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Reply # 1551383 on 1550830

Johnny Spacek

We are on Motorhome number 6 and none of the tank monitors work the way they should - interior or exterior mounted. Use them only as a guide.

Since your probes are interior you might try the following, it helped us get a better reading.

In an empty tank put a

- 1/2 gal bleach

- 1/2 quart Calgon Water softner

- A tray or more ice cubes

- About I/2 tank water

Travel to your destination, empty the tanks, flush again

This procedure helped clean the probes for a period of time.

NOTE: Do NOT do this procedure too often, bleach is not good for rubber gaskets.

I hope this will help.