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Topic: Fresh Water Tank Sensor Error (Tank Monitor Sensor Board) (Read 844 times) previous topic - next topic
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Fresh Water Tank Sensor Error (Tank Monitor Sensor Board)
The other day I drained my fresh water tank and filled with fresh filtered water.

The tank is completely full. I know this because fresh water is exiting the breather hole as well as the fresh water tank hose entry.

When depressing the monitor “Readout” display button, the Fresh Water LED’s briefly display all lights to indicate a full tank but within less than a second the LED’s for Full and 2/3 go out leaving only the 1/3 full LED lit. Very strange.

I added 8 ounces of White Vinegar to the tank two days ago and waited 48 hours. Very little has changed other than the 2/3 LED remaining lit for only slightly longer before turning off.

Today I drained and filled the fresh water tank with tap water in an effort to “clean” any possible residue from the sensors. One would think that if two sensors were “dirty” the lower one (1/3) would suffer from the same cause.

I’ll give the chlorinated city water a day or so to sanitize the tank. I’ll monitor any changes.

Other than adding Sea Level sensors to the tank, is there something that I should be doing to remedy this situation? I’m wondering if there is an access panel to the interior of the tank. Since ours is a RB the tank is just underneath the drivers side couch.

Otherwise, all is well. Happy New Year.

Kent

2015 27' RB "MissB.Haven"
Re: Fresh Water Tank Sensor Error
Reply #1 –
This is a whole lot of guesswork, but...

The tank sensors are basically screws that penetrate the tank wall and report conductivity when wet.  If you had corrosion on the inner end of the sensor, you should not get a reading that appears, then disappears.  If they sense water, your reading would stay on.  The fact that the display initially shows full, then cycles down to 1/3 suggests to me that the issue is not with the sensors, but is with the electronics that control the display.  I doubt that cleaning and flushing the tank will be of any help.

... and that is all I can offer.

Ken F in NM
'08 MB
Re: Fresh Water Tank Sensor Error
Reply #2 –
Hi Kent. Happy New Year!  In my older motorhome before the LD; it didn't come with tank sensors. I designed and built a fresh water tank sensor, that worked well with a used display I bought from a friend. The light bulbs lit up, using leakage current through the water (some salt ions) to turn on a transistor. So  one day I ran out of water at Yosemite. Late October all of the dump stations were closed, so I snuck some out of a hose behind a gas station (also closed). My fresh water sensor didn't work! A teaspoon of salt added to 35 gallons, and it resumed reading properly. The water was actually pure enough to not conduct enough electricity for measurement.
      Maybe your tank is too clean, and the water too pure. Your sensors work at first and then fade away, as if the water just won't conduct enough. The tank sensors don't have a lot of surface area in contact with the water, so the water doesn't have to be very pure to not conduct the minimum current required to light a segment. That small ground contact at the very bottom has to source enough electricity to light up three sensors for the full reading. That is probably why the lowest light (closest to the bottom ground contact) sort of works. How does it read with straight Long Beach tap water? Your sensors should work again.    RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Fresh Water Tank Sensor Error
Reply #3 –
Can you see the sensor pegs in the water tank on a RB?  I know you can on a MB (behind the water pump door), which would make troubleshooting this problem much easier. 

If the 2015 system is the same as the 2003 system, then the system is pretty simple.  You could have a problem with the pegs (not my first guess), the wires between the pegs and the readout, or the readout itself. 

Rich
'03 MB in NC
2003 MB
Re: Fresh Water Tank Sensor Error
Reply #4 –
Thanks Ron & Rich,

Rich, since the tank is directly below the couch, I haven’t yet spotted the sensors. I’ll climb underneath in a bit and see what’s visable.

Ron, thanks for the saline tip. As I’ve just added a fresh tank of LB water (pretty hard water actually) the sensors have not responded except for the brief readout before lowering to the 1/3 sensor. I hope these simple fixes take effect.

I have already removed the monitor panel and all wires are tight (although for about 6 months the generator LED does not light while the genny is running...but that’s less of a concern at this point).

Everything has been working as normal as recently as my trip to Indian Cove before Christmas and the water level has been lowering as I do use the “facilities” as it resides in my drive way (don’t tell my neighbor down the street 😖).

Still hopeful to have a resolution before the MB GT in March.

Thanks,

Kent
2015 27' RB "MissB.Haven"
Re: Fresh Water Tank Sensor Error
Reply #5 –
Since you have the monitor panel off and have access to the wires:  If you are comfortable with a multi-meter, check for continuity between the various wires that attach to the sensor pegs. 

With the tank full of water, I think you should find continuity between any 2 of the pegs.  If you get that, you have narrowed the problem to the display.  If not, you should be able to figure out with peg/wire combo is causing the problem. 

You can also swap wires around, to have the 1/3 full wire read as 3/3 full for example, to troubleshoot.  I like to take a cell phone picture of the way things are when I start to make sure I can get them back to their original positions. 

Rich
'03 MB in NC
2003 MB
Re: Fresh Water Tank Sensor Error
Reply #6 –
Since we are on the subject does anyone know how To remove the top sliding portion of the couch? Accessing the fresh tank would be nice in the even of a leak but it seems the couch sliding design does not allow for this.
2000 RB
Re: Fresh Water Tank Sensor Error
Reply #7 –
The couch is a two piece mechanism. The top section slides out and is kept in place with a rail that has a small bit of wood that attaches to the slide rail and goes below the two rails that keep the slide parallel.

Above the tank are two panels of wood that are screwed down to either side of the slide rail. Unscrewing the slide rail from the couch will release the rail and allow you to lift the couch section and set it aside.

Once the couch section is removed the panels above the water tank can be unscrewed and removed. This will expose the tank.

Here’s a pic of what you will find. The “red” shows the panels above the tank. The “yellow” shows the “rail” and the slide area. The “green” shows the small piece of wood that keeps the rail from popping upward and in the track. The “blue” is the couch panel that slides outward to increase the depth of the couch/bed.

Reassembly is the reverse. Don’t loose the rail. I’ve actually never done this but it looks pretty straight forward.

Hope this helps.

Kent

P.S. I’m having trouble uploading pics. I’ll try again later.

2015 27' RB "MissB.Haven"
Re: Fresh Water Tank Sensor Error
Reply #8 –
For a mid-bath floor plan since the fresh water tank is behind the kitchen counter. 

The best freshwater indicator I have seen on an LD was a length of plastic tubing mounted on the exterior of the cabinet below the sink. It was connected to the tank so that the level in the tube changed with the level in the tank. They are called sight gauges. You can see examples by Googling. No wires, always accurate.

PS you can always get on your knees with a flashlight and check the level.

In our rig, on the fourth day, we are in need of water. no gauge required.
Don & Dorothy
Sold our LD in June of 2023

Our boring always non-PC travel blog
Traveling Dorothy
Re: Fresh Water Tank Sensor Error
Reply #9 –
"PS you can always get on your knees with a flashlight and check the level."
----
This has been my MO from the get go; the crude gauges provide only a rough suggestion of what any tank levels might be.  ;)
2003 TK has a new home
Re: Fresh Water Tank Sensor Error
Reply #10 –
As I worked on the fresh water tank sensor error yesterday, I took some time to look at the monitor panel a bit closer. I also looked underneath the RB to look for any exposed elements of the fresh water tank.

There are no parts of the tank visable from below. No wires exposed so road damage is not possible as far as I can tell.

The Monitor wiring to LED’s is solid state. Included here are photos of what the board looks like.

So far, not much has changed with the exception of one very important element. Some of the wiring harnesses have very delicate wires. While reinstalling the monitor into the wall, I managed to break one of the leads to the propane detector from its pin. 😖 I used a bit of solder to reestablish the connection to the pin. One day, perhaps, I’ll replace the pin. If anyone decides to remove the monitor panel, just be careful while reinstalling it. There are a lot of wires back there. 🧐 You’ll notice in my pics that my propane tank appears to be full. It is not. This reading is a result of the broken wire. Ouch.

Also included today is the pic I took of the couch frame above the water tank. Getting to the top of the tank is fairly straight forward, but not something I’m ready to do quite yet unless absolutely necessary.

I did read in the LD manual about hard water causing sensor errors so I will, most likely, follow the cleaning procedure outlined in the manual.

And so it goes.

Kent
2015 27' RB "MissB.Haven"
Re: Fresh Water Tank Sensor Error
Reply #11 –
“PS you can always get on your knees with a flashlight and check the level."

Unfortunately the RB fresh water tank is hidden very well beneath the couch and is not visable. I wish it were.

Kent
2015 27' RB "MissB.Haven"
Re: Fresh Water Tank Sensor Error
Reply #12 –
Quote from: Kent Heckethorn  - 
“PS you can always get on your knees with a flashlight and check the level."
Unfortunately the RB fresh water tank is hidden very well beneath the couch and is not visable. I wish it were.

Kent

A SeeLevel system will cure your inability to get an accurate reading. I installed one after my wife ran out of water while washing her hair. It's worth every penny not to go through that experience again YMMV.
Garnet 709-P3W SeeLevel II Tank Monitoring System
The SeeLevel show the tank's levels in 4% gradients, instead of 1/3, 2/3 and full readings. It is one of the more popular enhancements I have installed over the  years.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fresh Water Tank Sensor Error
Reply #13 –
Larry,

I like the idea of ditching the tank monitors currently in the LD. The SeeLevel you linked appears very cost effective.

I wonder about the wiring to the current LD monitor wiring harnesses. Mounting the sensors appears to be easy enough. It’s the wiring that makes me hesitate. Are the existing LD wires spliced into? Is the SeeLevel monitor plug-n-play? While I’m okay with things I’m familiar with, some changes give me pause.

I suppose I should just pick up the system and take it one step at a time.

Taking a deep breath. 🤯

Kent
2015 27' RB "MissB.Haven"
Re: Fresh Water Tank Sensor Error
Reply #14 –
Here's how a SeeLevel system is installed.  First, ignore the existing sensors.  Instead, an inductive sensor is bonded to the outside of the tank.  It is a strip of flexible circuit board with an adhesive back.  It has two wires, one black and one blue, that are used to make the electrical connection.  The sensors are programmed for the black, grey or fresh water tanks by cutting a portion of the circuit board with scissors.  Install the sensors on the tanks.  Then, all the black wires are connected together with a single black lead wire which is brought up to the monitor.  Same for the blue wires and a blue lead.  The monitor has a black lead and a blue lead which are connected to the sensor lead wires.  It has other leads which get connected to 12v, to the propane gauge, and a ground wire.

The hardest part for me was figuring out how to thread the wires from the tanks up to the monitor, which I located near the ceiling.  The second hardest part was identifying the propane gauge wire.  Other than those two tasks, installation was quite easy.

You need to splice into a 12v source, into a ground wire, and into the propane gauge wire.

Ken F in NM
'08 MB
Re: Fresh Water Tank Sensor Error
Reply #16 –
I think I'll wait for the wireless Bluetooth version(s) to become available. With millions of RVs on the road, the after market demand for remote sensors should be quite high.

With household systems covering the initial R&D costs, unified systems tailored for RVs to provide different measurement readings should be fairly cost effective.

Any while you can route the information to a central monitor, a smart phone will be the more likely readout device of choice.
Re: Fresh Water Tank Sensor Error
Reply #17 –
Quote from: snerf  - 
I think I'll wait for the wireless Bluetooth version(s) to become available.
Any while you can route the information to a central monitor, a smart phone will be the more likely readout device of choice.

If such an animal became available, you would still have to route 12V and ground to each sensor panel and its bluetooth transmitter. Much more wiring than the single readout panel requires.

Steve
2004 FL
2013 Honda Fit
Re: Fresh Water Tank Sensor Error
Reply #18 –
Quote from: Steve  - 
If such an animal became available, you would still have to route 12V and ground to each sensor panel and its bluetooth transmitter. Much more wiring than the single readout panel requires.

I will take a simple, hard-wired device almost anytime over any Bluetooth device, installed in an RV.
I have friends who installed a Bluetooth controlled electrical system in their LDs  and watched them dealing with problems with the controls and readout, having to reboot and troubleshoot the system. 

Bluetooth, and it's ilk, would add more complexity to a basically simple system of measuring the level of the tanks.
Everything does not need to be wireless, hardwiring is usually cheaper, more dependable and a lot easier to troubleshoot.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
 
Re: Fresh Water Tank Sensor Error
Reply #19 –
The See Level gauge was installed in our LD within a month or so after it was purchased and we are much happier with it than the built-in gauges.

I have had to replace a couple of tank sensors both the gray and black. However, the black still is not accurate. We have tried several different cleaning methods including having the tank pressure washed with no real improvement. Have spoken with service at the mfg and they suggested a possible ground wire connection issue. Checking what I think is the connection point found no problem. The only reason I haven't pursued it further is that it becomes accurate when we get within about 20% of full.

Jim
Re: Fresh Water Tank Sensor Error
Reply #20 –
Quote from: Jim & Gayle  - 
The See Level gauge was installed in our LD within a month or so after it was purchased and we are much happier with it than the built-in gauges.

 However, the black still is not accurate. We have tried several different cleaning methods including having the tank pressure washed with no real improvement. Have spoken with service at the mfg and they suggested a possible ground wire connection issue.

Most issues with SeeLevel sensors I have seen have been traced to poor wiring connections. I now solder all the connections to the bus wires.
The sensors must be in direct contact with the tank, they sometimes pull free at the top or bottom of the sensor.
Duct tape can be used to reattach the sensor if the adhesive backing has failed. I usually tape the sensors in place until the tanks have been cycled a few times to make use they sensors are in the right position.
Our once a year, week-long septic tank enzyme soak has keep the tanks clean enough that sensor errors are not a problem.
Sensors do fail, have you tried another sensor in the back tank?

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fresh Water Tank Sensor Error
Reply #21 –
Having a TK I just look push the flush and look into the black tank.   I can see if it need dumping or not.   Flesh water, pull out the bottom drawer next to the sink.  Can see the level of water.  Gray tank I just guess.  Got really good after five years of use. 

personal fine art photo stuff
TF Mack | Flickr
It's all good .......
2014 Twin King
Re: Fresh Water Tank Sensor Error
Reply #22 –
Quote from: Larry W  - 

Sensors do fail, have you tried another sensor in the back tank?

Larry

We replaced the black tank sensor which altered the error but did not eliminate it. When the tank is completely empty the readings can be all over the place. It changes erratically day by day and by flush until it gets around 80% then it will settle and as it gets closer to full it reads reliably. I can't speak to all the wiring but it appeared to have been competently done and wrapped in loom or whatever that stuff is called. I'm not 100% sure I found the ground connection but I think I did and it was tight and no sign of corrosion. I loosened it and re-tightened it to be sure but again no fix. We've learned how it works and it hasn't been a problem.

Jim
Re: Fresh Water Tank Sensor Error
Reply #23 –
"Having a TK I just look push the flush and look into the black tank.   I can see if it need dumping or not.   Flesh water, pull out the bottom drawer next to the sink.  Can see the level of water.  Gray tank I just guess.  Got really good after five years of use."
----
Ditto.  ;)  
2003 TK has a new home
Re: Fresh Water Tank Sensor Error
Reply #24 –
Quote from: Joan  - 
"Having a TK I just look push the flush and look into the black tank.   I can see if it need dumping or not.   Flesh water, pull out the bottom drawer next to the sink.  Can see the level of water.  Gray tank I just guess.  Got really good after five years of use."
----
Ditto.  ;)  

Can't see into the black tank on a 30' model.

Jim