Aktiv system was what came on most of the Passats imported in from '90? to
'94 - it had a hookup to the tranny control and cruise such that as speed
increased, the radio volume also increased automatically.
IIRC, there were two or maybe three leads that were part of this and you
either had to use them correctly or not use them at all - otherwise you
would apply voltage to the controller and burn out it and a little resistor
on the back of the cluster circuitry as well - leading to no cruise and a
Usual first symptom was you could drive fine, use the cruise control - as
soon as you turned on the radio, the cruise cut out. Shut the radio off,
cruise worked fine again. After doing this for a while, the tranny would
start acting up (hard shifts, hanging in gear, etc)
About $1300 to fix, btw....