With your years of vehicle it is a simple matter isolate the cause of
the flashing. Both your Vanagon and your Quantum have virtually the same
electrical system. In the main relay panel of both, in relay socket #3
is a coolant level warning control unit. This relay will have a large
number "43" or "42" printed on the end that is visible. The warning unit
monitors the coolant level sensor in the main coolant tank. When ever
the sensor says the coolant is low for more than a few seconds, the
control unit starts flashing the warning LED in the temp gauge. Once the
flashing starts it will continue until the key is turned off and back
on. All you have to do is pull the relay from socket #3. If the flashing
stops and does not return then you know the problem is with the coolant
level detection system. If the flashing returns even with the relay out
you can be sure that the problem is in the instrument cluster, probably
the temp gauge internal electronics. The temp gauge is a separate piece
and can be replaced.

Mark

Craig, Jim M. {PCNA} wrote:

>Looking for some help from the collective before ignoring my family
>obligations for a few afternoons chasing down a few nagging gremlins on
>my '90 Westy this weekend.
>
>1.  The red led on my temp gauge blinks sometimes, but the needle on the
>gauge itself works fine and never goes higher than it should.  If I turn
>the van off, then restart, the light will turn off.  The cooling system
>is working properly.  My '86 quantum syncro wagon does the same thing
>and has for 5 years.  I am finally annoyed enough that I want to track
>down the source on both rigs.  Is it one of the sensors on the
>engine/cooling system or a problem with the circuit board on the
>instrument cluster, or could it be some sort of short in between?  If
>the instrument cluster, do I need the whole thing, a new tach assembly?
>..........................
>
>