The light to indicate the fill level on the kitchen water tank of my 1991
Volkswagen Vanagon GL Campmobile is behaving oddly.  The tank is empty.
The middle (yellow) of the three lights is on when the switch is moved to
the left (check level) position.  Of course, the bottom (red) light should
be on.

Does anyone know why?  I assume that the sender is bad in some fashion, or
that there is a short somewhere in the system that mimics a partially full
tank.  But if someone knows exactly where to look first, that would be
great.

mcneely