95 Golf, manual transmission

My cruise control, air conditioning, and coolant temperature indicator
all stopped working more-or-less simultaneously (within a few weeks of
each other).  Also, the coolant level warning light and oil pressure
indicator lights flash sporadically.  (Oil pressure is fine - I
measured it - and there's plenty of water in the coolant reservoir.)

Do these systems have anything in common? (wiring harness?)

thanks,
Tobin