Grey water tank sensor- 06 Meridian

Magredvet · 09-30-2015, 11:58 AM

For some time now, the grey water indicated is showing a 1/4 full light, even after I have just emptied it. I've had this issue on other RV's, and it was due to a dirty in-tank sensor, however, the Meridian is supposed to have external sensors, which don't need cleaning.
Anyone had this happen, and know of a solution ?
Thanks in advance

NoMoreAZ · 09-30-2015, 01:39 PM

How hot is it where you are?

Ours started doing the same thing in the summer in the southwest US. When it gets cooler tank says MT. When hot out says one-t..d, I mean, one-third. Only grey water, not black tank.

Maybe sensor coming off side of tank. Ours are difficult to reach, so haven't done to much.

Clay L · 09-30-2015, 04:18 PM

The external sensors can be fooled by wet crud build up on the tank walls just like the through wall sensors. Usually the black tank seems to be affected more than the gray through.

The three TrueLevel sensors on the side of each tank are active (integrated circuit) devices in series. As the liquid level rises and each sensor "closes" it causes a change in a voltage on the control board.
The control board uses LM339 Low Power Low Offset Voltage Quad Comparator ICs to sense the voltage change and activate the appropriate LED. There is no adjustment for this. There is an adjustment for the propane which still uses the old style potentiometer sensor.

If either of the two wires from the sensor string are broken or has a bad connection none of the three LEDS for that tank will light.

ChasA · 09-30-2015, 06:39 PM

That's funny. My Winnebagos sensors showed 1/3 tank increments.
I had the problem of an empty gray tank showing 1/3. I put in a cup of Calgon liquid water softener and 1/2 cup of Dawn mixed into 2 gallons of water. I poured this mixture down the galley sink and then put in enough water to bring the gauge up to 2/3. I then drove 200 miles to my next destination. There, I dumped the gray tank. My gray tank gauge has been working fine ever since.

Magredvet · 10-01-2015, 06:38 AM

Quote:

Originally Posted by ChasA

That's funny. My Winnebagos sensors showed 1/3 tank increments.
I had the problem of an empty gray tank showing 1/3. I put in a cup of Calgon liquid water softener and 1/2 cup of Dawn mixed into 2 gallons of water. I poured this mixture down the galley sink and then put in enough water to bring the gauge up to 2/3. I then drove 200 miles to my next destination. There, I dumped the gray tank. My gray tank gauge has been working fine ever since.

Maybe it is a third ( I just know I have 4 lights )...I'll check that tonight.
I'll try the above method, when we move this winter.
Thanks for all the info guys !

emcee · 10-01-2015, 07:46 AM

My 1/3 full grey tank light has been on for months now. Tried the dawn/calgon method. I even disassembled the tank drain piping and reached up with a rag on a stick and wiped the inside of the tank where the sensor is. No change.

Since I have access to the sensors I may try to change the sensor. I will try to find a new one instead of swapping one of the other working sensors.

GG1 · 10-01-2015, 09:04 AM

We had the same problem. My wife does a lot of cooking subsequently there is a lot of dish and pot washing washing. Grease and oils build up on the sidewalls creating a film on the sidewalls worse than the black tank. Now we try to use paper plates as much as possible and wipe off everything that gets washed before it goes into the sink. Also use Dawn dish soap, and pour a tank cleaner from a company called Roebic Industries into the gray tank when you travel to flush out the tank. Also don't run the gray tank with the valve open continously let it build up now and then for a complete flush. This seems to work for us.

Cheryl Bisson · 10-05-2015, 03:47 PM

Same problem, too. Poured a full large bottle of liquid dishwasher detergent down the sink drain along with hot water. Then ran a hose from the house hot water heater drain faucet into the sink and ran hot water until the gray water tank was full. Drove 200 miles and then drained the tank at our site. Also started using a capful of Calgonite liquid water softener every time tank was emptied. Also made sure all dishes and pots were wiped off before washing. And the two biggest things that helped IMHO was to stop using oil in the water when I cooked pasta or rice as the water was being dumped down the drain. And, secondly, I switched to Dawn dish detergent. After all of these changes, our sensors began reading accurately, and I have stopped using the Calgonite.