Fuse 72 drain question

[DougM]

I have a battery drain at fuse 72 in a 2001 x5 4.4. I have read through tons of threads and an wondering if anyone ever pinpointed to what aspect of that system was causing the drain. Is it attributed to the radio? My car does not have sat/navigation or CD changer. It used to have the factory phone which has been cut out.
Is there a way to completely disable certain aspects of the system while maintaining just the radio and speakers? I assume that the black box on the driver side(US) is the base of those systems. It has a few different multi wire leads to it.

[jaima]

Try another relay (points/contacts might be closed) , it could be providing constant power to the radio?

[DougM]

Which relay?

[jaima]

Audio Nav relay in the rear above the fuses, light green in colour, the one closest to the rear seat.