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Old 11-23-2016, 09:27 PM   #1
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THOR #5820
Black tank not reading

During our last trip I noticed the black tank was not reading. It showed empty the 4 days we were out. I drained the tank and cleaned it by putting a rotating sprayer down through the toilet. I then completely refilled the tank with fresh water and it still reads empty when full...Am I looking at a bad sensor or did I not get it clean when spraying out the tank?? I was under the impression that a dirty sensor would give you a high reading.....We have a 2016 Vegas

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Old 11-23-2016, 09:47 PM   #2
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You can always check the wiring. The black tank is the one closest to the outside of the camper (you see it when you open the hatch on the outside). Check that the wires are still connected to the probes on the front end of the tank--especially the bottom one.
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Old 11-23-2016, 09:51 PM   #3
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If you had/have a sensor that reads anywhere near accurately then you'd be the first one. After 4-5 different rvs I've never had one work past 1-2 times when new. You can try cleaners, the magic Geo method, wave a magic wand, rinse til your blue in the face, replace sensors & from my experience all you will get is more aggravated. My black last about 7 days, when I notice a different sound when flushing, I know it's time to dump, my bath grey is always open til a day or 2 from filling black & galley grey will last til draining the black. The grey sensors don't work either after a while.
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Old 11-23-2016, 10:01 PM   #4
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I checked the wiring before writing this post and everything looks in place...I'm thinking bad sensor????
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Old 11-23-2016, 10:07 PM   #5
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I hear ya, I'm not to worried about it but if it is a bad sensor and I'm still under warranty I might as well have it replaced.....
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Old 11-23-2016, 10:21 PM   #6
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My black is always 2/3s full even when empty or full.
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Old 11-23-2016, 10:26 PM   #7
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I really can't see this as being a bad sensor. This is because the "sensors" are just bolts through the tank wall--there is nothing to them. The meter just reads the resistance between the different sensors to determine the tank level (if you really want some in-depth inner workings of the system read this thread: http://www.thorforums.com/forums/f27...nsor-1177.html ).
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Old 11-24-2016, 12:57 AM   #8
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when I dump my black tank and rinse I then put in the digester tab and half bottle of Dawn dish soap. It may take a couple of times for you to degrease the sides of the tank My sensors always work following my routine. hope it helps you
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Old 11-26-2016, 10:03 AM   #9
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I always leave about 5 clean gallons in to slosh around when driving unless it's too cold of course.

Never used digester tabs or wand cleaning or anything complicated or agrivating. When I bought mine the sensors didn't work and now they do.

In the black tank lots of water is your friend!
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Old 11-26-2016, 01:28 PM   #10
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Quote:
Originally Posted by Travelin' Texans View Post
If you had/have a sensor that reads anywhere near accurately then you'd be the first one. After 4-5 different rvs I've never had one work past 1-2 times when new............ The grey sensors don't work either after a while.
X2. On three different RV's mine have never consistently worked. On this Challenger I checked them for the first couple of months until the black stopped working, now I never use them.
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Old 11-26-2016, 01:58 PM   #11
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I've had similar experiences with previous RVs: Black tank sensors were rarely accurate and always seemed to read one LED higher than the actual tank level.

On the Axis, however, we had the tornado flusher installed. So far they have read pretty good. I have noticed that on occasion that they start to read off but some extra flushing when dumping seems to clear it up for a while. (One of the reasons I haven't really installed the DIY level sensor...)
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Old 11-27-2016, 11:24 PM   #12
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As you have gathered by now, errors in the tank sensors is very common. Usually they read more full than the tank really is. Reading empty is unusual. If the tank is near full does it still read empty? If it is full of just clean water it may not indicate anything. If that is the case, put some salt in the tank, but rinse it out since it could cause some problems.

I would trace the wires to make sure they are connected.
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Old 11-28-2016, 01:28 AM   #13
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The tank read empty when full of dirty water, drained, cleaned tank with a tank sprayer through the toilet and then filled the tank full with clean water still reads empty... Traced the wires everything is in place...
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Old 11-28-2016, 01:31 AM   #14
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If you can crawl underneath: With the tank empty check the voltage between the top and bottom probes when someone is pressing the button on the panel. You should get something close to 12V as none of the probes will be shorted by the tank fluid. If you get 0V then the circuit isn't getting power somewhere.
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Old 11-28-2016, 01:36 AM   #15
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I will try that, thanks
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Old 11-28-2016, 01:38 AM   #16
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Originally Posted by Tony&Sheryl View Post
The tank read empty when full of dirty water, drained, cleaned tank with a tank sprayer through the toilet and then filled the tank full with clean water still reads empty... Traced the wires everything is in place...
I am not familiar with the electronics that convert the resistance readings of the level sensors but something takes this info and converts it to the level in the tank. Since everything else is good, that would be the next thing to investigate.
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Old 11-28-2016, 08:04 AM   #17
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THOR #3916
Went to the "SeeLevel (or SeaLevel ) system & was able to use the existing wiring, also has a remote readout(digital % of full) that I put next to the oem display.
they attach to the outside of the tanks.... works like a charm
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