My trailer is brand new and during first camp noticed the gray tank sensor went to 2/3 and then F very quickly. No big deal, I had a full hookup so I just pulled the lever and dumped. Figured I just needed to become aware of how much water we use to wash with, etc. Our gray tank is 30 gal. Same thing happened the next day: very little usage and the sensors quickly showed full. In the meantime, after 3 days of camping with a family of 4, the black tank (also 30 gal) showed 1/3 full. That seemed reasonable to me. Got back home and had time to run some measured experiments today. After 6 gallons, my gray sensor showed 2/3 full and at 12 gal began showing FULL.I understand people's black sensor showing higher than it really ease due to toilet paper or crud clinging to the sensor, but I don't get why my gray sensor would be acting this way since it's at worst soapy water. Thoughts? Ideas to rectify the situation?

when the water nolonger drains or you see paper floating in the pipe they are full do not rely on the sensors they are junk in all of them

Is it possible your gray and black tank are 2 different sizes?Do the same experiment again, only this time, keep filling the gray until water back-up in your drain. Then you'll know REALLY how much is truly holds. Black tank... I never use the sensors. Just look down the toilet hole! Works ok for me.

DutchmenSport wrote:Is it possible your gray and black tank are 2 different sizes?Do the same experiment again, only this time, keep filling the gray until water back-up in your drain. Then you'll know REALLY how much is truly holds. Black tank... I never use the sensors. Just look down the toilet hole! Works ok for me.Sorry, I left that part out: at 26 gallons the gray water began to back up into the tub (you could hear it before it started). I will run the same experiment on the black tanks and report back. I am pulling the specs for the gray and black tank sizes off the manufacturer website but my experiments will tell if these are accurate. In case it matters, the trailer is slightly off level back-to-front with the rear of the trailer lower by 1-2". It was pretty level at the campsite though.

texasAUtiger wrote:DutchmenSport wrote:Is it possible your gray and black tank are 2 different sizes?Do the same experiment again, only this time, keep filling the gray until water back-up in your drain. Then you'll know REALLY how much is truly holds. Black tank... I never use the sensors. Just look down the toilet hole! Works ok for me.Sorry, I left that part out: at 26 gallons the gray water began to back up into the tub (you could hear it before it started). I will run the same experiment on the black tanks and report back. I am pulling the specs for the gray and black tank sizes off the manufacturer website but my experiments will tell if these are accurate. In case it matters, the trailer is slightly off level back-to-front with the rear of the trailer lower by 1-2". It was pretty level at the campsite though.Are you sure the tank is emptying completely when you drain it? Could there be something preventing it from draining all the way?

I have no reason to believe that it is not emptying completely since (1) the outlet doesn't seem to be moving any water (by listening and feeling), and (2) it took about 24 gal for the supposedly 30 gal tank to back up into the tub. I conjecture the 6 gal difference to being out of level. I appreciate all the feedback. Keep it coming.

Sensors on new trailer | Good Sam Community

Clay_L
Explorer
Jul 10, 2015
If you have the Ventline sensors that go through the side of the tank and they are installed at the correct height they may have potentiometers on the display board below the LEDs that can be adjusted.

As side note the problems with the sensors are not due to crud on them, but rather crud on the tank walls that is wet and fools the sensors. This happens even with the external sensors like Sealevel and TrueLevel (installed by Winnebago as standard since 2005).
It seems to occur more with rigs that get a lot of use, like full timers.
BubbaChris
Explorer
Jul 10, 2015
We are primarily dry camping this year, so I'm getting to "know" my fresh and gray tanks better than last year.

So far I've been able to confirm on multiple trips that my gray sensors will show 2/3 full before my fresh sensor shows I'm 1/3 empty.

I haven't measured for specifics, just confirmed they aren't very accurate.

On the good news side, we managed 4 Navy Showers last weekend without any issues. Our tanks are 37+6 Gallons Fresh, 37 Gallons Gray.

PS - I noticed the sensor is labeled "Grey" not "Gray." Were they aiming for some upscale British image of the waste water?
quingus
Explorer
Jul 10, 2015
On our class c the control panel never really seemed to be accurate. I had a brand new interstate battery and two 6v T 105's put in, checked the panel. They both read low. So I just figured ok well garbage sensors not much I can do, but keep a log on a spreadsheet as to checking batteries with a fluke, easy and if I use the appliances all the time fill propane any chance I get. Spreadsheet was attempt at humor.
GaryWT
Explorer
Jul 09, 2015
Might need to replace the panel.
OLYLEN
Explorer
Jul 09, 2015
I don't know why they even bother putting the sensors in, They never work. Guess it's to make us feel good "we got lights". Seelevel is the only brand that seem to work at a reasonable level pun intended.

LEN
texasAUtiger
Explorer
Jul 08, 2015
wbwood wrote:
You mentioned that you were not level when camping and just figured 6 gallons of error because of that. It can also cause your tank sensors to not read correctly.

I need to eliminate that variable for sure then. I will do so when we go camping this weekend. I will level it up and see how the sensors perform.
wbwood
Explorer
Jul 08, 2015
You mentioned that you were not level when camping and just figured 6 gallons of error because of that. It can also cause your tank sensors to not read correctly.
texasAUtiger
Explorer
Jul 08, 2015
Ok, more data for you guys...

I ran the experiment on the black tank (twice to make sure). Both confirmed the following:

Ran the hose straight to the toilet with flap open. At 25 gal, the black tank was filling up to the point that the water line was meeting the flap. Black tank sensor read E the whole time.

Next, I hooked the hose to the backflush port on the exterior of the trailer. Same results: 25-26 gals and the water line was to the flap, yet the black sensor read E.

So it seems I have an overreporting gray sensor and severely underreporting (or inoperable) black sensor. (However, the black sensor DID go to 1/3 when camping.)

Seems like the sensors are no good despite the trailer being brand new.
GaryWT
Explorer
Jul 08, 2015
I know that my gray tank will fill in a day with 2 showers and doing the dishes twice. Mainly because of this, we leave the gray tank open and just close it before the last 2 showers of the weekend. The black tank we can easily go 3-4 days so I do not watch that at all either. Seems to work for us. Once you camp a few times you will see what works and it will be part of the routine.
texasAUtiger
Explorer
Jul 08, 2015
I have no reason to believe that it is not emptying completely since (1) the outlet doesn't seem to be moving any water (by listening and feeling), and (2) it took about 24 gal for the supposedly 30 gal tank to back up into the tub. I conjecture the 6 gal difference to being out of level.

I appreciate all the feedback. Keep it coming.