The only problem I've ever had with VW cruise is the vacuum switches on the
brake/clutch pedals. If you have a Mityvac, the switches can be diagnosed,
in situ.  You might even get away with just depressing the brake pedal, then
cycling the switch repeatedly to get the seals to re-seat themselves.

I found that if I disassembled the switch, cleaned it and reassembled, the
problem went away.  Or, you can just buy a new switch, if they're still
available. YMMV

Casey
'89 Bluestar
Oly-Wa...very wet