Holding tank sensor issues

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Fishin_Fool

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May 16, 2023
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Hillsboro, OR
I have a Class C Winnebago Outlook 31C. It has the stick on tank sensors on grey, black and fresh holding tanks. The tanks have been empty for a while since we haven't traveled much in the last few years. When I hit the levels switch on the main control console, black tank reads full, fresh and grey read 2/3. Any idea why these are reading like they are? I looked into replacing the tanks sensors with the Garnet Seelevel system. BUT, my control panel is an all encompassing including generator start/stop switch and hr meter, pump, water heater switches as well as the level indicators. Any help as to how to troubleshoot or maybe just have to replace all the sensors would be helpful.
 
John Canfield said:
Most likely the insides of the tanks have dried residue which causes the sensors to read erroneously. On my 2005 Horizon I installed a Garnet SeeLevel which is significantly more reliable than the factory level monitor.
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John, when they check to see what the levels are, the fresh water tank reads 2/3 full. That tank shouldn’t have any scum in the inside I wouldn’t think. Also these sensors are the stuck on ones on the outside of the tanks. I’m not familiarity how those work.
 
No help on the sensors, but tank sensors very seldom actually work correct in most situations.

It's really best if you learn how to monitor your water use without depending on the sensors, or just routinely dump your holding tanks and fill your fresh water tank on a schedule and then you'll never have to worry about it.

I know my fresh water tank holds approximately 50 gallons and 45 is actually usable from the on-board water pump. I almost always dump my tanks using my 32 gallon Barker Blue tote which I transport to the dump station or at home, to my septic tank.

I use a water meter when I fill my fresh water tank. I know we can do 1 load of laundry (7 gallons of water) and 4 showers comfortably... and .... use the toilet for 2 days .... and wash dishes for 2 days (twice a day) and just come close to filling the 32 gallon tote so it won't overspill. So, when camping longer than just a weekend, this is my "schedule".

To confirm my water usage, I attached a garden hose attached water meter so I can monitor how much water is actually being filled into the fresh water tank. If the total is more than 32 gallons, I know I have to split trips to the dump stations.

Monitoring this way, confirmed we can go 2 days comfortably and stay within the 32 gallon limit of my tote.

This works. I don't use the the sensors at all.

Get to know your camper and get to know your own water usage and you won't need those sensors either.

And by the way, I do not dump my black tank when it is "full". I dump it regulary, no matter how full or empty it is. They say to dump with "full". I do not. That's because, when I dump, I always ... ALWAYS .... back flush my grey shower/laundry (grey) tank water into the black tank and flush it out. It doesn't matter what's in "there", the back flush pulls everything out. You back flush after the tank is empty. I've been doing it this way for over 20 years. Never had a problem with the black tank doing it this way ... never.
 
DutchmenSport said:
No help on the sensors, but tank sensors very seldom actually work correct in most situations.

It's really best if you learn how to monitor your water use without depending on the sensors, or just routinely dump your holding tanks and fill your fresh water tank on a schedule and then you'll never have to worry about it.
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True, sensors are usually about as accurate as fuel tank sensors on a boat...they're not. You just have to Kentucky-windage it until you know how far off it is.
 
Tulecreeper said:
True, sensors are usually about as accurate as fuel tank sensors on a boat...they're not. You just have to Kentucky-windage it until you know how far off it is.
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That's so true. Here's my marine fuel gauge story:
Silverleaf VMSpc report

Back to RV tank sensors ... I gave up relying on them years ago. On our coach, I shine a flashlight down the commode and I'm able to see past the apex of the two 45 degree bends to view the level.
 
Tom said:
That's so true. Here's my marine fuel gauge story:
Silverleaf VMSpc report

Back to RV tank sensors ... I gave up relying on them years ago. On our coach, I shine a flashlight down the commode and I'm able to see past the apex of the two 45 degree bends to view the level.
Click to expand...
I've seen it the other way round a few times. Fuel gauge reads 1/4 tank, the boat runs dry 10 miles from the marina and has to be towed back in the dark.
 
Rene T said:
John, when they check to see what the levels are, the fresh water tank reads 2/3 full. That tank shouldn’t have any scum in the inside I wouldn’t think. Also these sensors are the stuck on ones on the outside of the tanks. I’m not familiarity how those work.
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From first hand experience, I can tell you they don't - even the fresh water sensors. Hard water has a lot of suspended particulates that could precipitate out even in cold water.

Also from first hand experience I can tell you the Garnet SeeLevel works very well so the technology is available.Winnebago doesn't pick the best technology on the market for whatever part/component/assembly but one that is suitable (sort of :whistle: .) And that meets cost requirements.

One example is the old Dimensions inverter/charger, it was custom built for Winnebago to a cost point. When I replaced that Dimensions, it weighed about half of the replacement Xantrex I installed. The Sleep Number bed we had was also a special model for Winnebago. When we replaced that with a regular mattress I took apart the 'brain' (electronics) and noticed only part of the circuit board was populated - some standard features were removed for the Winnebago version.
 
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Yes. Those are the ones. However, all 3 holding tank sensors are reading falsely. I don't think all of the sensors would go out at the same time. Winnebago customer care suggested cleaning the tanks and doing the bag of ice and driving around trick for the black water tank. For the near future, I'll just guestimate the grey water since I can visually inspect the black and fresh tanks as to the level.
 
You can "test" those sensors: Remove the set from the tank that is easiest to work with. With the sensors removed, still connected, place your thumb over "plus symbol" on a sensor. It should register on your display as the first level. Does not matter whicj sensor you test. The first one should register at the lowest level. If that works, cover the second, then the third. If you get no indication on the panel then the sensor is bad and you will need a set. If they do register then the problem is inside your tank or a poor attachment.
Amazon has the double-sided tape that was reccomended to me by RecPro
 
Mine were on with double-sided tape. The new sensors (3 in the kit, wired together) I ordered came with the tape on the sensor, just peel the backing. I had two bad sensors on the grey tank. Prepped the tank with isoprpyl alchol and they have been good.
 
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