BMW E38 - No Sound, Audio problem - MK3 - Sat NAV - 728i
I have a 2001 UK BMW 728i Sport with a factory fitted MK3 Navigation system running v25 (3-1/62).
Since around a year it has been giving me sound problems in general. All the functionalities of the Navigation/CD/Radio/Cassette and OBC are operational but there is no sound from the speakers most of the time.
I have had this checked from BMW - Holland Park who initially performed a £80 diagnostics and said they think it could be related to the ignition switch as a correlated sign was the airbag light coming on intermittently.
Replacing and testing showed no change - except the sound system started working more often but no reliability; so they put the original ignition switch back on.
BMW now say it could be the radio controller at the back @ £550 + VAT. As I understand this is integrated with the Audio Driver/Amp.
I have physically checked - all connections and units are secured properly.
Has anyone else seen a similar problem ? Any ideas or checks or tests I can do to identify the root cause or a fix ?