.......the problem may be connected to the door interior light switch. Don’t know if its a coincidence but the interior light in only activated when the drivers door is open not the passengers door. If that is the problem is the switch in the door or the pillar.
I have exactly this problem on my S3 only in reverse ie the drivers window does not drop / no interior light. Has been diagnosed by RTC as broken switch and due to be replaced shortly.
Tried to follow the directions in the manual for the cruise control in my first few weeks of ownership and as far as I could see it didn't work at all.
Personally with all those horses to control I like to have the reins in my hands at all times and I really don't see how a cruise control works properly without an autobox so in my view it is a little bit of excess weight and something else to go wrong.
(I'm also an ex +8 owner!!)
Looking forward to your pics........
