Keith Ovregaard wrote:

> Here's another blinking light story. My 84 Westy's coolant light has
> been staying on for about 2 minutes after I start her up. Once the
> engine is warm and I restart, the light will react in the normal way
> (blinks for a few seconds and goes out).
>
> I checked the coolant level (no air in expansion tank), checked the
> sensor prongs (clean), checked the sensor plug (fine), and the grounds
> are fine. The coolant was changed last spring by a competent VW
> mechanic using the blue VW coolant. If the sensor can detect a weak
> coolant to water mix, would this be a possible cause? Is the resistance
> different when coolant gets heated up a bit?
>
The idea that the light flashes because the coolant mixture is not 50/50
is the vanagon list version of an urban legend.
  I tried to lay this to rest back on 27 July 2001.  The subject of the
post was: "Coolant resistance thru coolant level probe", if you want to
find it in the archives.
The bottom line is that after careful testing, I concluded that if the
probes are reasonably clean and connected properly, most any water
solution has a resistance low enough to satisfy the level sensing
circuitry, if the electronic parts in the dash are working as intended.
 Other listees have addressed the issue of problems with a capacitor, I
believe, at the dashboard end.

Larry A.