Just installed Horst sensors in my black tank..empty tank reads fine BUT when the tank gets 1/3 full, indicator reads 2/3 as it did with old sensors..color coding on wires to sensors is correct..white/ground...yellow 1/3 sensor, and green for 2/3 sensor.....Am on a trip and seeking ideas or solutions..
Just installed Horst sensors in my black tank..empty tank reads fine BUT when the tank gets 1/3 full, indicator reads 2/3 as it did with old sensors..color coding on wires to sensors is correct..white/ground...yellow 1/3 sensor, and green for 2/3 sensor.....Am on a trip and seeking ideas or solutions..
Ted, I would pull the yellow wire from the 1/3 sensor and touch it to your ground lead and see if it lights the 1/3 indicator, I am betting it lights your 2/3 indicator.
I had a similar problem on our last camper when it was brand new, When I got it home I filled all the tanks to full to make sure no leaks occurred and while I was walking out the door I just happened to push the gray tank level indicator and it said it was full, which was impossible since the water had only been on for 3-4 minutes!
I got underneath and checked the wiring and per the info found on the forums the colors were correctly installed at the right positions so I jumped each wire to ground and sure enough the lowest sensor lead made the full indicator light up. So, knowing it was miss wired somewhere between tank and indicator panel I pulled the panel and it was a spaghetti factory behind there and I did not want to break into the hardwired bundles so I just swapped wire positions on sensors, filled the tank while watching the indicator and it worked as designed, never had another problem with it.
Troubleshooting the Micro-Monitor
Ted,
When working as designed:
The 1/3 light is really a "Not Empty" light and will come on after a few flushes (see photo). The 2/3 Light is actually about 1/2 full see location of sensor.
The F light is about 7/8 full when it comes on.
As with all these type sensors, LEVELNESS of the tank effects readings.
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Lou & Freya the wonder dog
2008 GMC Sierra 3000HD Allison Duramax
2019 Flagstaff 8529FL
Still troubleshooting this issue.. I first removed the yellow, green, and orange wires from the new Horst sensors and checked the resistance of each one to the resistor pack input red wire and they were within specs. I then connected each disconnected color wire to the ground and the appropriate indicator (1/3 - 2/3 - full) appeared to work ok. I reconnected everything and the tank read empty...Good so far.. Then I started filling it slowly with water just until the 1/3 indicator came on but at the same time the 2/3 indicator also came on... I disconnected the the green wire and still 2/3 indicator was on... I drained the tank and disconnected the sensors again and read the resistance between the ground and 1/3 sensor expecting infinity but instead it read 110K ohms.. This is with new Horst sensors installed and an totally empty tank.. I don't understand how this could be but something is shorting the new ground / 1/3 sensors... Next step is to again clean the rank with the wand and some type of tank cleaning chemical or cleaner.. Any further suggestions / ideas would be appreciated..
I had trouble with my gray tank because we camped for a week with my DD who has really long but thin hair. Her hair got caught on the Horst probe spiral and would not wash off. I needed to pull, clean, and reinstall them.
The black tank has directional flats on them. It is critical that the flats on the studs be oriented with the flat down. That way the hood is over the wire and NOT under it. Examine the studs and make sure they are all with the flat down.
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Lou & Freya the wonder dog
2008 GMC Sierra 3000HD Allison Duramax
2019 Flagstaff 8529FL
Thanks Herk for all of the information you have provided me.. That is what makes this forum such a valuable asset to many of us... I rechecked to make sure the Flat Side of the Black Tank Horst probe connection is down.. Understanding how resistance is figured in DC circuits, my next step is to (1) pull the 1/3 and ground probes to visually inspect them and (2) give the tank a good / long flush to make sure all possible sludge that might contact between the probes is removed... I believe that residual sludge is causing the problem.. will keep all advised of progress..
You can try disconnecting the wires and hook the sensors up one at a time till you see which one has a short to the tank wall. You may need to relocate the 1/3 tank probe if it is embedded in crusted, well, crud.
Try a Unique RV-Digest-It treatment before you go any further.
Herk... In your last response, you wrote.."Fill the tank with warm water and dump a full quart of RV-Digest-It RV Digest-It Holding Tank Treatment or Rid-X RID-X® Septic Tank System Treatment Products | RID-X® Septic system cleaner in the tank and let it "stew" for 72-96 hours.
Question?? I have to go on a week long trip.. Is it OK to leave the RV Digestit treatment at this (full qt) strength in the tank to "stew" for a week or so before draining/flushing without damaging anything?
Could it be the little red module/wire harness that the probes connect to and send the info back to the monitor panel could be bad?
The resistor pack is very easy to check (see values in the attached troubleshooting guide). These are normally very reliable and I don't think it is the trouble in this case.
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Lou & Freya the wonder dog
2008 GMC Sierra 3000HD Allison Duramax
2019 Flagstaff 8529FL
Linear Mode
