I have same problem in my 2000 v40 T4. If you already check wiper motor and wiper control stick. It most probably fault of CEM (Central Electronic Module). Just replace it, every resume normal.

I have similar problem in my V40 T5 wipers. When I switch on the wipers, nothing happen. I had changed wiper motor and wiper control stick, but still fail. Finally, I changed CEM (Central Electronic Module), every resume normal. You can locate this module down in the steering. Just move out 6 screws...