Maybe, but I would be more inclined first to blame a weak ground
connection for the instrument cluster. VW connected a lot of dash stuff
through one ground point and if that connection point is weak there can
be feedback in the cluster when other circuits are active. Try reseating
the 14 pin connector on the lower right side of the instrument cluster.
If that does not help, I would jumper a new ground wire from exposed
metal of the body to the brown wire on pin 3 of 14 pin connector as a
test and possible fix. Rudimentary knowledge of the use of a Volt/Ohm
meter helps.

Other causes of blinking people have experienced include loose nuts on
the back on the temp gauge. These tiny nuts make the contacts for the
gauge leads to the blue foil. There is also a known failure inside the
gauge itself that has been reported as being worse in cold/damp, at
least at first. Since headlights get used more at night and night is
colder than day it may be the cold as much as the lights on that
increases the occurrence of your problem. It may be a combination of
these things. It may be a fault in the blue foil itself

All the above assumes you have eliminated the coolant level circuit as a
cause. In 86-91 it is a simple matter to remove the coolant level relay
from position 3 of the main relay panel. It should have a large 42 or 43
stamped on the exposed end. Pull this out for a while and very if the
problem still exists with it missing. If so, the cause of the  problem
is likely as discussed above.

Mark

Stephen Edwards wrote:
> Hi all.
>
> Mark Drillock's explanation makes me wonder if this is related to the
> problem I'm having.
>
> I have a Vanaru conversion which was done about two years ago.  Since
> the first winter I've had a problem - used to be intermittent, now
> extremely frequent - with the coolant LED coming on when the coolant
> level was not low, and the temp not particularly high.
>
> Recently I noticed that it is most likely to happen when the
> headlights are on - and almost 100% likely when the lights are on
> high beam.
>
> Sounds like I should check the voltage regulator - exactly where is
> the little bugger and what does it look like?
>
> TIA
>
> Steve, 91 GL with 1995 Subie 2.2.
>