Water keeps running--tank will not fill up--why?

Many RVs have the plumbing to fill the fresh water tank from the city water hook up. This valve is usually near the city water hook up and labeling is similar to "city water" and "tank fill". Another anomaly from leaving the valve in the "tank fill" position is that, when not connected to city water, the on board pump may run continuously and the water volume is very low.

Fill the reservoir with white vinegar and run a cycle. Discard the vinegar and repeat the process a second time. that should remove the scale and reset the flashing light.

if the water keeps flowing then try replacing the flapper if it still flows then the fill tube gasket or tank to bowl gasket need to be replaced.

2 possibilities.1. The water level is set higher the the overflow tube. This will cause the water to run into the overflow continuously. You should be able to see this. 2. The large seal - bottom center of the tank - is leaking. This will cause the water level to slowly drop after a fill. The water tank will start to run again after flushing - BUT NOT CONTINUOUSLY. You should see if there is a small amount of water flowing from the rim to the bowl 15 seconds after the water has stopped running after a flush.

If any toilet runs (continues to fill) when it is not being used, there are basically 3 reasons. the most obvious is that water is leaking out all over the floor so the fill valve thinks the tank has not reached its volume of water. Next, the rubber device that keeps the water in the tank when not being used (most commonly called a flapper) has warped from time or chemicals in the water (NOTE:chlorine eats rubber for breakfast daily), and and allows water to seep past it, which lowers the water level and triggers the fill valve to come back on to top things off.
The third reason is because there is particulat in the fill valve or mineral buildup and internally it doesnt always properly seal so it can run intermittently or all the time.
All the parts on the TOTO ultramax are warranteed for 5 years so keep that in mind if it applies.
Remove the tank lid when you hear the fill vave working and look at the water level. If the water level is below the top of the white plastic tube that the flapper is connected to (often called the overflow tube), then you have a bad flapper. If the water level is going over the top of the tube then you have a defective fill valve.
Out of warranty fill valves can easily be replaced with a Lavelle "Quiet fill" available at most hardware or plumbing stores or online.
This valve is what Toto uses in most of their toilets and it is only the removeable cap that is different (subliminal advertising maybe)

It sounds like the fill valve is not operating correctly. Remove the fill valve which it the tall item inside the tank where the water runs through and replace it with a universal replacement part from your local hard ware store. Take the valve to the store so that you can get the proper replacement piece.

the fill valve shut off level setting is too high. water in the tank is overflowing in the overflow tube. adjust fill valve to shut off at lower tank level

your rad cap is bad

The duration of the rinsing cycle is equal to the amount of water you have in the water tank. I don't believe they tell you this anywhere in the manual! I own a Titanium SS and it rinsed and rinsed and rinsed the first time I performed it! I figured out it will just keep going until the water tank sensor tells the machine it is out of water which is equal to saying to it: "Thanks for using all the water i wanted you to use to rinse, now you're finished." It takes a LONG time if you fill the tank. If you keep filling the tank, it will just KEEP going. Be patient, let the tank run out of water and this will trigger the end of teh cycle. Hope this helps, Tony.