I am thinking this is the capacitor in the gauge.  here are the symptoms:

-coolant tank is full.
-light blinks intermittently.
-seems to do this less often when the ambient temp in the van is warmer.
-sometimes turning off the key and turning it back on will correct the
problem.
-sometimes turning the key to on, the light will stop flashing after a few
second, other times not.  when it does stop, if you start the van it will
stay off.  when it doesn't stop, if you start the van, it sometimes will
turn off, other times not.

What do you think David Beierl and other vanagon electrics experts?

Thanks,
Edward