Alan,

Try to reseat the connector to the instrument cluster.  My '85 used to do
this regularly.  What it worked out to be is that the connector oxidizes
over time, causing low voltage to the instrument cluster.  The light does
not reset to its normal condition after self checking.  Used to drive me
crazy in the mornings.  Another symptom you may notice is that the gas gauge
reads low.

I have heard (second hand) that you may want to check the voltage regualtor
on the PC board as well, but I wouldn't mess with it upfront unless there
are other instrument problems.

If it really bothers you, you could get CDI out in Victorville to look at
it. They appear to be quite knowledgable on VWs and vanagons (I lived in
Mendon for about a year, so used to stop in there.  Fortunately, for the
year I lived there, my '85 never needed anything major)

Hope this helps, feel free to p-mail me if you have any specific questions.

Scott