I had this blinking light problem last winter and ended up having to find a
new connector (the one with the tiny contacts that plugs into the sensor).
It is the same as for some other same-era VW car, don't remember which. But
it solved the problem. Three years ago or so I had the problem, the light
would blink light crazy and would only stop when I turned the engine off
and restarted, then it would randomly start up again. I had recently
installed a south african dash foil replacement. Contacting the
manufacturer didn't help, they had no idea. Then one day I discovered--the
light only blinked if the dash fan was running. I bought another dash fan
(the kind that sits on top of the dash and plugs into the cig lighter) and
that solved the problem completely.

I know these two things won't help you but they might help you look for the
weird thing that is causing your problem.

Jim

On Fri, Sep 16, 2022 at 12:25 PM Ed McLean <email99@nc.rr.com> wrote:

> Please check the following Vanagon Technical Service Bulletin clip where it
> states the resistance, checked with a digital multimeter, must be between
> 31K Ohm and 65K Ohm and the coolant concentration must be below 60 percent
> for proper Coolant Indicator LED operation.
>
>
>
> https://beakerbus.nl/2016/vw-vanagon-technical-service-bulletins/
>
>
> Technical Bulletin
> Group:    90
> Number:   92-03
> Date:     February 29, 1992
> Subject:  Coolant Indicator LED is Flashing at Normal Temperatures
> Model(s): All Models
>
>
>
> * refer to appropriate wiring diagram
> * disconnect coolant level sensor electrical connector
> * check coolant level in coolant reservoir
>    *** MUST be between MIN and MAX marks
> * set digital multimeter, Fluke 83 (US 1119) to ohms function
> * check resistance of level sensor with digital multimeter Fluke 83
>   (US 1119)
>   *** must be between 31K Ohm and 65K Ohm with correct COOLANT LEVEL
>       AND COOLANT CONCENTRATION.
>
> NOTE
> If coolant resistance is NOT within the above specifications, the
> coolant MUST be drained and replaced with NEW coolant mixture of
> 50 percent water and 50 percent phosphate free coolant antifreeze,
> Part No. ZVW 237 104.  (In Canada, use Part No. G 001 100).  The
> mixing should be performed before filling vehicle cooling system.
>
> *****************************************************************
> * CAUTION                                                       *
> * Coolant concentrations of 60 percent or higher will cause the *
> * overtemp / low coolant LED to activate.                       *
>
> End
>
>
>
>
> On Fri, 16 Sep 2022 10:35:38 -0600, OlRivrRat <OlRivrRat@COMCAST.NET>
> wrote:
>
> >        Pretty darn sure that that Coolant Level Probe in the Expansion
> Tank
> >
> >is nothing more sophisticated than a simple Switch > When the Probes are
> >
> >Submerged > Circuit Closed,, When Coolant Level drops below Probes the
> >
> >Circuit Opens ~ Any Break in the Circuit will cause the Light to come on ~
> >
> >There are some Electronic Components within the Circuit that can cause the
> >
> >light to have some odd behaviors @ times ~ I have seen, in several
> different
> >
> >Vanagons, a condition where if the Igni’Key was turned to Start in a
> normal
> >
> >way (1 continuous move from Off to On to Start) the Light would Stay Lit
> >
> >but if the Igni’Key was turned to On & left in that position for 10-15
> Sec’s
> >
> >before turning to Start then the Light would go Off & act normally ~
> >
> >I suspect that D Beierl or Dennis H or others may have an explanation for
> >
> >that condition ~
> >
> >
> >
> >> On 16 Sep , 2022, at 9:33 AM, Ed <email99@NC.RR.COM> wrote:
> >>
> >> I believe the coolant light circuit measures resistance between the two
> pins
> >> of the sensor in the plastic tank.  If the resistance is out of range
> then
> >> the light will come on.  If the coolant is low or sloshes away from the
> >> sensor pins then the light will come on.  If the coolant has too much
> >> antifreeze then the resistance between the pins will be out of spec and
> the
> >> light will come on.  If the pins are dirty or corroded then they might
> read
> >> incorrect resistance.  There could also be a fault in the wiring for the
> >> light that could cause the light to come on.  I don't know how to test
> the
> >> sensor.
> >>
> >> That all I have.
> >>
> >>
> >>
> >> On Fri, 16 Sep 2022 05:57:37 -0700, David McNeely
> <davmcneely40@GMAIL.COM>
> >> wrote:
> >>
> >>> Doesn't the coolant light indicate the level of coolant, not the
> >>> temperature?  I have actually had it come on when I hit a rough spot in
> the
> >>> road, back some years ago.  Bouncy, bouncy, and the light blinked on
> and
> >>> off.
> >>>
> >>> On Fri, Sep 16, 2022 at 5:16 AM Ed McLean <email99@nc.rr.com> wrote:
> >>>
> >>>> The original note was a short question asking why the coolant light
> would
> >>>> turn
> >>>> on and off at random times for no apparent reason while the
> temperature
> >>>> gauge
> >>>> remained in the normal range.
> >>>>
>