Tank Sensor Help

[BillMc40]

Picked up the travel trailer and during the walk thru the tech had all tanks full. After the walk thru and WDH install all tanks were drained for the drive home. After arriving home, I asked the wife I wonder if he drained all of the tanks. I had the fresh water during on the trip home. So I pulled the gate valves on the grey and black tanks (fresh water was all that was in them) nothing came out. I checked the tank sensors fresh,grey both showing empty. Black is showing full. There is nothing in it unless I am missing something on the drain system. Pull gate valve labeled black water. Please help
BillMc

[bigbird]

The only way to know if the black tank is empty is by looking down the toilet. You'll find the black tank sensor is rarely accurate.

[tinlizzie23]

My OEM tank sensors are usually fairly accurate on both grey tanks, but the black tank frequently is misleading. I have sometimes just drained the black tank, KNOW it is empty, but the sensors will read full. Other times, same scenario, and they will read empty.

Before next camping season, I have decided to install HORST Miracle Probe sets in all 3 tanks. Have heard nothing but praises for them, and they are guaranteed by the manufacturer to remain accurate. There is a shield over the black tank sensors to keep toilet paper from "shorting" the sensor, so it won't affect readings. They are supposed to fit in the original holes, and use original wiring.

These Horst probes are available on Tweetys, ebay, Amazon, and other places, but NOT from Camping World (My local Camping World never heard of them).

[mtelkhntr]

I have an older Jayco TT that I purchased new with insulated tanks which essentially means a tank within a shell with insulation between them. The outer shell is metal and when new, either the wiring or back side of the sensor was shorting to the outer metal shell giving a false reading but once it was repositioned and not contacting either, the sensors on mine have worked flawlessly.

[slabat]

I installed a set of Horst probes and would highly recommend them. They are easy to install and since I have installed them they have been accurate.

[clutch]

The black tank is seldom accurate. All it takes is a small piece of toilet paper on the sensor and it will show mostly full. I have a friend that adds 5 gal of water to the empty tank and then dumps three or four bags of crushed ice down the toilet and takes a drive with lots of starts and stops. He claims it works every time. The tank on our trailer is 38 gal so I dump the black water every week. You can flush the toilet a lot of times and not have a lot in the tank.

[edatlanta]

I just flushed my black tank after being on a site for 4 1/2 months with no sewer hookup. My tank sensor has been stuck on full most of this time. After the dump yesterday and a "Good Long Flush" it did drop down one notch. I just don't pay attention to the black tank gauge. It is wrong 99.9% of the time and I gave up worrying about it. I only looked at it after the flush to see if it had moved at all.

[David472]

I've had some success clearing the black tank sensor by adding a "thimble full" of dish detergent and about 2 gallons of water. I do this right after dumping the black tank, so it's in there for the drive home and also for the drive to the next camping session. Some people add ice cubes to the mix, as clutch has suggested.

[troutslayer]

Originally Posted by BillMc40

Picked up the travel trailer and during the walk thru the tech had all tanks full. After the walk thru and WDH install all tanks were drained for the drive home. After arriving home, I asked the wife I wonder if he drained all of the tanks. I had the fresh water during on the trip home. So I pulled the gate valves on the grey and black tanks (fresh water was all that was in them) nothing came out. I checked the tank sensors fresh,grey both showing empty. Black is showing full. There is nothing in it unless I am missing something on the drain system. Pull gate valve labeled black water. Please help
BillMc

If this is a new unit, I suspect there is something wrong with the sensor. If it is a used unit, it is normal as the sensors get "stuff" hung up on them constantly.