Volvo Repair: Electronic problems, controller area network, damp weather

Question
Hi, I am the owner of a 2000 v70 2.4 automatic which has begun to have electronics problems. I have had the car to my local dealership who have charged over £600 so far and not cured the fault. They say that all modules are functioning correctly and although they have experienced the fault they cannot pinpoint the source.
It all begins with a rear screen wiper that has a mind of it's own. Occasionally, mainly in damp weather the wiper will operate for a few seconds on it's own. This is usually followed by losing the elecrtonic display, indicators and the electric windows(so far). This is usually followed with either an SRS warning message and triangle  symbol illuminating or a brake failure warning. Volvo have had the vadis machine on it but cannot locate a fault or find any recorded fault. Any  ideas?

Rob.  

Answer
Well I have had a similiar fault on a newer S40.  The wiper would have a mind of its own, the display would go dead, etc.  What I end up finding was that one of the controller area network wires was shorted underneath the carpet.  It was extremely difficult to locate, and it took me almost 4 days to find it.  I can;t be sure what your problem is but I know that its gonna take a while to find and it may or may not cost a small fortune.  This is probably one of the worst problems to have.  I wish I could direct you where to look but it could literally be anywhere.  Also a module could be causing the same symptoms without setting any codes.  As long as it only does it intermittently it will be almost impossible to find.

James