I've got a VW Sharan which has got a "non-factory" Radio/CD player
fitted. I've read on another thread.....

When you replace the factory unit, you need to install a signal
separator
Autoleads part number PC5 52. This is required on all VW, Audi, Seat and
derivatives i.e. - Skoda, Ford Galaxy, where the vehicle has a roof mounted
aerial. Otherwise you will not be able to pick up AM. Cost is around £10
from any car audio shop.

However the Sharan has an AM aerial on the rear offside window. Does
the same thing apply, ie do I need a signal seperator and is it the
one quoted?

Charlie