When you first turn on the ignition, the light blinks for a few seconds
(a function of the capacitor in the gauge) only to test the indicator
light ... not the sensor.  After that, the two pronged sensor in the
expansion tank is what is "Supposed" to trigger the blinking light, only
when the prongs are no longer emersed in coolant.

Corrosion at the electrical connector for the sensor can cause the light
to blink.  A bad ground can cause the light to blink.  A bad sensor (or
one with corroded prongs maybe) can cause the light to blink.  A bad
connection in the instrument cluster can cause the light to blink.  A
bad capacitor in the gauge can cause the light to blink.

An air bubble would have to be in the expansion tank in order to cause
the light to blink because that's the only place there is a sensor to
check for low coolant.

Mike

Kim Springer wrote:
> I have had a few responses to this issue so far.
>
> I never had this problem until a week ago.  The weather has been warm, unseasonably warm here in the SF Bay Area.
>
> My tendency is not to be too alarmed, but something has definitely changed, and it hasn't been the weather.  My thought about the long block change that made all this go away for John Lauterbach, is that there was another part he changed that actually fixed the problem, not the whole engine?
>
> So we all start our boxers and the light blinks for 5 seconds or so before it goes out.  Why?  Is the sensor a flow meter, so when the water gets circulating, that the light goes out?
>
> Or is that just a delay time for the computer to do all its checks on all the systems including the temp sensors?
>
> Perhaps I have a cooling system that needs bleeding, or has let in an air bubble, or maybe I have a flow issue related to an old radiator?
>
> Anyone know?  I'm searching the archives.
>
> Kim Springer
> 2WD Tristar #7
>