http://autos.groups.yahoo.com/group/C5-L/message/9549
Ok, i fixed the problem. First i removed the dashboard indicator unit, this is
5 min. work by putting a knife under the unit ,from the front, at the position
where you see a smal dot from 0.5 min in the plexiglass. you do this at 2
positions to unlock the unit and then it comes free and you can remove it.
The problem was a faulty torque motor from the speed indicator.I
interchanged the torque motor from the speedindicator with the one from
the revolution indicator (tachometer) and the speedindicator works great
now. Now i opened the faulty torque motor and found a plastic axis from 4
millimeter broken, i replaced it by a nail cutted to the same lenght and
installed it thrue the plastic housing (make the nail hot with a lighter) of the
torque motor. There is a spring in the torque motor which must be
installed with one revolution of force. Now i installed the whole unit in the
car again. When i installed the plug, the pointers moved to a random
value, but you must hold a few minutes to adjust the pointers to zero (by
just turning them to zero) because the unit will reset the torque motors to
zero.
They told me it will cost me 800 euro to replace the whole unit, finally it
costs me nothing but only a few hours to find out and fixed the it.