Community Forums

Kjon · 01-22-2022, 06:09 AM

Good Morning.
Black tank level sensor constantly indicates empty. I suspect a loose wire or perhaps it needs a good cleanout. Tank has been flushed twice using the tank flush port without effect. Any idea if a disconnected wire would cause either a false full or empty indication?

PKI · 01-22-2022, 12:43 PM

Yes, something has failed. The sensor pads may have come loose from the tank or the signal wires may have been pinched. Wiring may not have been connected at assembly or a part may be missing.

Expect that your coach may not fully drain the tanks when you dump them. We have to drop the DS and raise the PS to get most of the waste to dump.

There are service centers who can put a camera into the tank and inspect the condition and fluid level if that becomes necessary.

Good Luck with the resolution.

TXTiger · 01-22-2022, 01:23 PM

You don't State the make, model or age of your RV. Some older RVs have the sensors mounted inside the tank and some newer ones have them on the outside. Either was the sensor may have come unattached and is not reading correctly. Or as others have said a wire may have disconnected. My sensor is stuck on full. I just know when to dump by the number of days since I last dumped. Also as a back up, I know when my shower won't drain and it's time to dump the gray. I always dump the black first at the same time I dump the gray. I rarely even look at the gages any more.

Kjon · 01-22-2022, 01:59 PM

Hi TXTiger. Perhaps the signature block on my post is not working as it has the Make / Model / Year etc. I'll double check it. Your suggestion is what I am doing at this point. The other tank level indicators are working.

alank · 01-22-2022, 05:59 PM

Find out where the sensors are located and have a look at them. Possibly the first sensor came unstuck from the tank. Does the second or 3rd sensor come on when the tank is fuller, or have you not filled it that much? I reattached the sensors on my tanks, and they have been perfect since. Mine were on the ends of the tanks on the passenger side.

Kjon · 01-23-2022, 07:28 AM

Problem disappeared last night, sensor appears to be working now. I'll give it a good flushing out today. Thanks for the advise.

PKI · 01-24-2022, 08:22 AM

A good flushing is always a sound idea, but is not likely the problem. If there is a lot of material/waste/fluid in the tank, it will show full, not empty. Empty, when you know there is waste in the tank is likely a wiring disconnect or another type of sensor fault. The sensor pads do have to make contact with the tank to function properly.

Kjon · 01-25-2022, 01:12 PM

As I understand it, each of my tanks have 3 sensors mounted such that they indicate 1/3, 2/3, and full. The fresh and grey water indicators seemed to be working. Until recently, the black tank not so much. To avoid any possible problem, I dumped the black tank frequently flushing it each time. Time will tell if the problem reoccurs.

Gfarr · 01-28-2022, 09:19 PM

I had the same a similar problem of blank tank not showing full, discovered the full sensor had come loose and fallen off on the outside of tank.

thegats1 · 01-29-2022, 07:35 AM

I have the Red 340 33AL. Black tanks sensors failed. Tiffin fixed them (replaced them I believe). Stopped working again. I have a pretty good sense on when it is full. Also, when I personally add to the tank, I simply look in the tank from the toilet hole. My eyes are better than any sensor when it is full. Anyway, I stopped looking at the panel tank levels. Grey still works, but interestingly enough I know it is full when the bathroom sink won't drain (not the shower). I've been told by another Red 340 owner he had the same issue and it was related to the way the tank is constructed causing the portion where the sink is draining to fill first (or may be related to the drain line penetration location). Honestly, I don't care either way. I'll just dump it and go on about my business. Maybe I will care when boondocking (I'll just lift the DS or PS side up higher to break the vapor lock I suppose).

Steve4152 · 02-01-2022, 08:54 PM

I had a similar problem shortly after taking delivery of my coach in 2020. As Gfarr mentioned, I found that two of the sensors had detached from the side of the tank. I reattached them, and haven't had a problem since.

kandcbend · 02-01-2022, 11:34 PM

Quote:

Originally Posted by PKI

... There are service centers who can put a camera into the tank and inspect the condition and fluid level if that becomes necessary.

A colonoscopy for the tank; I'll bet that is expensive

harp54 · 02-02-2022, 10:26 AM

As mentioned before check that the sensors are glued on and no wires broken. also check if in a area that no metal objects are laying against them or touching. I had a false reading on a gray tank and found a can of bug spray was laying against the bottom sensor and causing bad readings. I cleared the area out and seems all good now.

Kjon · 02-02-2022, 12:03 PM

Thanks to all for their advise. I can see all 3 tanks from outside the wet bay but the sensors must be on the opposite side. I may have to move some dirt to get my old body under there.