this is wierd! black tank senor problem

dougrainer wrote:

Mile High wrote:
Interesting, I always thought the Tecma shared the same sensors with the other system based on the Thetford manual, but evidently not.

They do NOT, due to the dirty tank problems that plague normal RV tank sensors. Also, they really want the FULL shut off signal at about the 75 percent level. The Manual is very clear that they are separate sensors. Doug

OK DOUG - LOUD AND CLEAR - THANKS FOR PUTTING EMPHASIS ON THE WORDS YOU FELT WERE IMPORTANT AND SORRY THE MANUAL WAS LESS CLEAR TO ME THAN YOU.

Find the sensors and make sure the red one has not fallen off.

The sensors are not interchangeable according to the tech I talked to.

You may need a hose designed for cleaning the tanks.

The in tank sprayers clog often on some models.

There's the Geo Method...

I tried that a couple times and it worked, for a short period.

But to me, all these cleaning methods are merely a short term fix. I really object to the 'flush and fill 4-5 times' in nearly all portions of the country that are experiencing 5 year or longer droughts. Our recent string of massive storms seem to have alleviated the worst of it, but it'll be back. So I don't recommend wasting water like that as a general rule.

What I do is simple. I tape a piece of paper on the wall and keep count of the days between dumps. And I know when it's time to dump when water starts filling the tub or shower stall and/or when the toilet begins to smell. I test this two three times over a long period and shorten the time between dumps to avoid the filled shower or smelly toilet.

Once I've zeroed in on my usage and fill patterns, which by the way, was 2 weeks between dumps in my Bounder, and 1 week between dumps in my Journey, I just keep a chart on the wall and enter the date when I dump.

I've found that just keeping track of the grey water is fine. I always keep the valves closed until time to dump. And use Calgon and Dawn occasionally in between RV park hops with 2/3rds of a full tank to help wash things. Used ice 2-3 times but it never helped.

When I have a guest, I just shorten by half the time between dumps.

So, for the last 10 years of full timing, I rarely pay attention to the LED lights because they lie.

5 times filling and dumping. Last 2 clean out no residue coming out. Green light and empty. Within less than 2 hours red light was back and 1/3 full. Still wierd, and problem not solved.

Mile High wrote:
Interesting, I always thought the Tecma shared the same sensors with the other system based on the Thetford manual, but evidently not.

They do NOT, due to the dirty tank problems that plague normal RV tank sensors. Also, they really want the FULL shut off signal at about the 75 percent level. The Manual is very clear that they are separate sensors. Doug

Interesting, I always thought the Tecma shared the same sensors with the other system based on the Thetford manual, but evidently not.

Add some Calgon water softener too...that helps..helped me when I had the one toilet in my last coach...I hated that Tecma toilet and I have one of those now but at least a normal one in one bath...

"I also found that a cup of liquid Dawn left sitting in the tank as long as possible seems to keep it clean,"

If you can take a drive it will help.

dougrainer wrote:
Usually there is a slime/debris buildup on the wall of the tank. The Tecma's is a glue on sensor and picks up the inside with a sonic type electromagnetic sensing system. Buildups can cause it to go crazy and not sense the correct inside level. Try multiple flushings (4 or 5). This means filling the tank FULL and then dumping. It is best to have a clear adapter at the sewer outlet on the hose. This way you can watch if you get debris after each flushing. You may only see debris as the last 5 to 10 gallons rush out on each flush. Doug

X2. I also stand by the ice cube method. Dump a lot of ice in the toilet, drive around letting it slosh the debris hoping it will whack off the debris on the sensors.

It is good to know we are not alone with this. We have been filling the tank and dumping the tank at least 3 times when we dump. So I suspect that a hard water film build up is possible. The wall and bottom that we can see of the tank is clean, so I am wondering if there is anything that will remove it. Will try full wash out 4 or 5 times and see if that helps. Thanks for all the suggestions.