All tank sensors read empty

[28Bunkhouse]

I am experiencing a problem where all tank sensors are reading empty. I filled fresh and still reads empty. Could the wall unit that reports levels be faulty?

[Mike484]

Knock on wood, ours still work. I have been told by many that the sensors will eventually fail, that they always do. Since ours is new, we have been monitoring our levels daily so when they do decide to quit working, we will have an idea of how long we have before we will have to dump the tanks. So far, it looks like the black tank is about 4-5 days, the gray tank is 3-4 days, depending on how many showers we take. Most of our camping is on 3 day weekends so we are safe to just wait until we are packing up to dump the tanks. Longer trips we are normally never in one place for longer than 3 days so we dump when we are leaving and if we do stay longer, we will dump on the third day.

[sourdough]

From my experience the sensors are good for a short period after an initial new purchase. After that you're pretty much on your own. After 3 summers in this one they are hit and miss no matter how I try to "clean" them. Having owned trailers without sensors in the past we pretty much know when we need to dump without them. The guidelines posted by Mike484 are pretty close and depend on your usage and how big/many holding tanks you have. We have to dump gray pretty quick unless we go to the old "military" style of showering; which I don't do unless boondocking/hunting. Then I can make the gray tanks last a week no problem for 2 people.

[28Bunkhouse]

We can make it 8 days for 2 people on all tanks, galley is the smallest.we take military showers sparingly. Problem is the none of the tanks are registering, I was wondering if the sensor panel could be faulty?

[chuckster57]

When I read how sensors are junk and fail, I have to disagree. The sensors in my previous trailer worked perfect for the 13 1/2 years I had it. Current unit works perfect too.

OP: most likely a ground wire issue. One common ground wire between all tank sensor packs and frame.
Quick test is to jumper between the bottom sensor and good ground, should read empty if tank is empty. Then you can jumper from the bottom sensor to the one above it for 1/3 and the one above that for 2/3 and the top one for full.

If that works then check for the common ground wire. We have added ground wires in addition to the original one.

[Mandolin]

My new trailer has a fresh water tank that reads 1/3 full - even when I am pretty sure (having drained it completely) that it is empty. The dealer shrugged and said "well, these things are not particularly accurate."

So, either it doesn't drain completely when I turn the low-point valve stub (which, as far as I can tell, is the only way to drain it) or the sensor is already off. It does go higher than 1/3, but never lower.

What we have done in the past to winterize the old trailer was to open all the valves and blow out the lines with air, put RV anitfreeze in the traps, so it would be important to know if a tank isn't draining (the tech at the RV dealer warned of a couple other things to look for, such as water right before or after the pump and water between the toilet and the tank).

The gray water sensor seems to work okay. The two trips we have done thus far in the trailer we haven't really used the black tanks.

Probably when we are out on our last camping trip of the season next week, we will take the time to fill all the tanks and record levels to be sure everything is working.

[Desert185]

When I read how sensors are junk and fail, I have to disagree. The sensors in my previous trailer worked perfect for the 13 1/2 years I had it. Current unit works perfect too.

OP: most likely a ground wire issue. One common ground wire between all tank sensor packs and frame.
Quick test is to jumper between the bottom sensor and good ground, should read empty if tank is empty. Then you can jumper from the bottom sensor to the one above it for 1/3 and the one above that for 2/3 and the top one for full.

If that works then check for the common ground wire. We have added ground wires in addition to the original one.

So, the ground wire you speak of is at the tank sensors and not behind the panel? So far, mine work great, but its nice to know the system.

[chuckster57]

I'll post a couple of pics with explanations.

[Mike484]

When I read how sensors are junk and fail, I have to disagree. The sensors in my previous trailer worked perfect for the 13 1/2 years I had it. Current unit works perfect too.

So, the sensors should continue to work and if they fail then its a simple fix?
Our unit is only 10 months old and the sensors still work, I am happy they do and I hope they continue to work. When I said that they will fail, this was not from experience, but from the words of many other owners who have told me not to depend on them. This is why we monitor our usage closely, in preparation for when they fail. Hopefully they won't, but if they do, I will take your advise and check all the wiring before I give up and just think that this is a natural occuring event. Thanks for chiming in on this, with your back ground in repairing RVs, I am sure that your knowledge is much better than the opinions (or lack of knowledge) of others is much more reliable.

[Dave W]

Ours have seldom been accurate including the fancy Horst Miracle Probes that I installed in the black tank before our just completed long trip. Usually 3 days with the gray tanks and 4-5 with the black tank work for us. But with that said, we never even had electronic tank level sensors for RV until the current and the last 5er. We 'knew' when to dump. As our 5er sits now in the driveway, the black tank reads empty, the 2 gray and potable all read 1/3. All will be flushed and washed as best possible and whatever the sensor reads is what it will be. I'd love to put a SeeLevel sensors system on the tanks, but since I can't easily reach two of the tanks, not gonna happen:eek:

[chuckster57]

So, the sensors should continue to work and if they fail then its a simple fix?

Our unit is only 10 months old and the sensors still work, I am happy they do and I hope they continue to work. When I said that they will fail, this was not from experience, but from the words of many other owners who have told me not to depend on them. This is why we monitor our usage closely, in preparation for when they fail. Hopefully they won't, but if they do, I will take your advise and check all the wiring before I give up and just think that this is a natural occuring event. Thanks for chiming in on this, with your back ground in repairing RVs, I am sure that your knowledge is much better than the opinions (or lack of knowledge) of others is much more reliable.



Not always a "simple" fix, but with proper use they should work correctly for years. I always cleaned my tanks, used Dawn in the gray tanks and rinsed the black real good. Sometimes when you dump you have to leave the valve open to dry it out. Condensation will give false readings. There are different styles of sensors and even "hoods" that drape over in some tanks.

As for THIS thread, all tanks reading empty leads me to a ground fault. I have uploaded some pics of a unit I'm working on at the moment with an open belly (makes picture taking easy), and when I get home I'll post with explanation.

[chuckster57]

Okay, I took a few pictures, and here is a quick lesson on the common type of sensor packs and monitor panel. First picture shows the sensor pack connected to the tank sensors. The three colored wires attach to the sensors in the tank installed at approximate volumes. If you look close there is a red pod that all the wires are attached to and a single wire coming out that attaches to whatever color the manufacturer uses for a signal wire. In this series of pictures it is the gray tank. Sensor packs use the same colors for all tanks.
http://www.keystoneforums.com/attachments/photobucket/img_214039_0_e535c7e222bba1b536c9c4779fab89a5.jpg

Next picture shows the ground wire. ALL grounds, DC and AC are connected at some point and use the frame.
http://www.keystoneforums.com/attachments/photobucket/img_214039_1_3978e0ab6dfa72067fec63e9762acd9a.jpg

Last picture show back of this particular monitor panel. Others are similar, this one only has three tanks- fresh, gray and black. Note the white wire, it is ground and connected to the white ground in the first pics and the trailer frame
http://www.keystoneforums.com/attachments/photobucket/img_214039_2_a4767805420c064f8666bb13f1e7af7d.jpg

Hope this helps, there are other systems, but this is the most common.

[mazboy123]

lots of interesting responses to this thread. the difference is that you have an atypical problem; most read full all the time or don't change.

unless you want to get dirty or spend a lot of money just monitor your gagues.
i.e. i know i can go two weeks with the black water, etc.

[Ken / Claudia]

Good information Chuck.
It seems that when there is a problem. The common problem is with one sensor or one tank not all. That is normally the black tank. This sounds like a ground problem to me also. So. far this trailer has not had any issues with sensors but, most I have had at some point give false reading mostly temperately.

[Desert185]

Everything seems chinzy or of marginal quality on these trailers. I think that once folks understand that, tolerance for the state of affairs will ensue. These crates aren't Prevost motorhomes or custom stick homes.

After living with the water/poop level indications over a period of time, I know approximately how long we can go without dumping. The critical item that determines the end of boondocking is the black tank. Level indication system malfunctioning? Just take a peek down the hole when you flush. Its full when the black water is insight. Simple, actually.

Drain backing up when taking a shower? Weeze a little gray water out of the tank...preferably before the wifey takes a shower. You will help the boondocking flora flourish.

[28Bunkhouse]

My tanks are enclosed as we live in the north. I would have to remove covering to get at sensors, can I test at panel?

[chuckster57]

My tanks are enclosed as we live in the north. I would have to remove covering to get at sensors, can I test at panel?



You would have to know what color wire is used for each tank. If you ground that wire to a known good ground, the panel should show full for that tank. Fresh tank may only read 2/3 if it has the newer KIB board.

[Richard Noble]

Problem I had was they all read "full". I had a bad monitor.