I have read several threads in the archives on this system, and also have
some experience on it because I own an 85 GTi with the same system.  But
wondering if this strange symptom I observed on a prospective 86 van sounds
familiar to anyone?  Start it up and idle, no buzz or light.  Rev it up a
bit, I assume it is going over 2000 rpm, and it starts buzzing and flashing.
Continues buzzing and flashing even after going back to idle.  That is the
strange part.  Turn off the engine and restart, and no more buzzing and
flashing until it is revved up again.  Seems to act the same hot or cold.
No strange engine noises or overheating.  Anybody seen this or think it is
cause for concern?  Sounds like a sensor or warning system problem to me.

Edward