I am located in Melbourne, Australia, and my W8 Passat has done 142,000km. It has just had the original battery replaced, but upon replacement, the electrical system no longer functioned properly. The rear vision mirrors, central locking, power windows, etc. no longer worked. The VW service people told me that the control unit under the passenger side floor had possibly been water affected. Can I access this myself, under the carpet, or is access possible only from under the car?
I have opened the control unit in the boot, which had water in it, cleaned it up with a toothbrush and dried it out. The central locking, air conditioning and rear vision mirrors are now working. The fuel gauge, however, is not, and the trip gauge is registering odd numbers (actually going backwards). Can you please tell me which functions are controlled by the unit under the floor and which are controlled by the unit in the boot?
The car is due to be returned to the VW service centre soon, so that they can continue to try and remedy the problems, but in view of my success with drying out the control unit in the boot, I would like to have a go at resolving the other problems myself.