200TQ - Voltmeter - still not working.... @%#!$*@!

["Peter Berrevoets" <peterb@mysysltd.com>]

My 1990 200TQ 10V is running great except for the voltmeter. I've tested it
directly and sure enough it works fine when not in the car.  When in the car
it only moves from the rest position to level with the first mark on the
scale.  It has once actually registered ~ 13v for about 10 seconds before
falling back to it's regular spot.  I unfortunately don't have a Bentleys
manual yet but this little quirk is beginning to really irritate me.

Can someone with a wiring schematic, or some insight, determine what might
be the culprit here.  All other gauges and electricals are working, the
climate control diagnostic shows 13.9 v.  All the electricals work except
for the console night lighting which I believe is burned out bulbs (the
buttons light when depressed) and of course the drivers side seat heater.
The car did have an aftermarket cell phone previously installed but that was
removed by the previous owner.

I've pulled the dash out three times now and all contacts/connectors have
been stab22'd. Is there a ground somewhere, or a possible circuit failure
(due to the cell phone maybe?) that I should/could check/fix?  I've assumed
that the Oil Temp Gauge works as it starts low and does move up to around
the 90/100 degree C range.

Any help or hints would be appreciated.

Peter B
1990 200TQ 10V

BTW fuel consumption has improved since the addition of the new
plugs/injectors/fuel filter from a previous average of 13l/100km to a
current 10.2l/100km all with an increase in real power, operating smoothness
and cranking time... excellent return on investment!