Hi I am new here and hoping you can diagnose a problem??

Got in my A3 today and tried to play my ipod though one of those cassette adapter jobbies and no sound came out. Flicked between tape and radio and no sound on radio either.

The audio system has been on its way out for a while after the 6CD changer jammed over a year ago (and didnt want to pay £250 to get it fixed), but the radio and tap functions have been fine since.

Anyway I set off, without music or radio, with the audio system switched off and got a strange high pitched whining coming though the car speakers. the whining seemed to somehow be linked to the revs of the engine and got higher pitched the higher the revs, dropping off when you dipped the clutch to change gear. Strange thing is the audio system wasnt on!!

Went into a multistorey car par and put the headlights on, the whining got louder, indicated and the whining crackled in time with the indicator clicks.

Radio switches on and off OK, but no sound. Whining sound occurs when radio/audio system is powered off.

WTF is going on?

2004 Audi A3 2.0TDi with BOSE stereo if that makes any difference?

Thanks for any help!!

Sorry for double post (alos posted in A3 forum), but wasnt sure which area would get the best response!