At 08:03 PM 9/15/2003, Katherine J. Maas wrote:
>A couple of weeks ago I had my 1987 Westy in for servicing.  I always take
>it to a mechanic I really trust.  He�s a VW specialist and works on lots of
>them.  He�s been working on my Westy since I originally owned it � for about
>4 years now.

However he doesn't actually understand electricity, and possibly not
troubleshooting.

>Thinking something else must have been malfunctioning, he bled the system,
>replaced the gauge (twice), replaced the temperature sensor, changed the
>vibrator,

Nice trick since this vehicle doesn't have one -- however we'll assume he
means the voltage regulator that supplies +10v to the fuel and temp gauges.

>  and checked all the wiring.

That's the part I don't believe.

This is a simple system.  You have a ten-volt positive supply, goes through
the gauge, then through the wire to the sender, through the sender, back to
ground.  The hotter the sender is, the lower its resistance and the more
current it lets pass which heats up the gauge and makes it read high.

There's also a low-coolant warning controller which outputs to this line
when is sees an open circuit on the coolant-level sender pins.  The version
you should have puts out a pulse that will trigger the flashing light
without noticeably changing the gauge reading; but the older type simply
forces the sender line to a level that approximates full scale.  This makes
the light blink and also makes the gauge peg.  The old controller is taller
than wide; the newer one roughly cubical.  They're on the fuse/relay panel
in the 2.1l, I think the painted number may be 43.  The old type will cause
your symptom if it's unplugged from the sender or has a bad ground.

So if you eliminate the level controller, what's left is a wire shorted to
ground between gauge and sender.

david

--
David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"