Thanks for the reply !
It is as you guess a bose system - my plan was to remove the head unit and replace it with a more modern unit
what happens is if you remove the unit the security system locks the parking brake, fuel gauge goes to zero , battery light comes on etc
is there a module available to stop this ?
Looking at the wiring diagram the speakers don't have individual amplification - line level signals of just left and right come from the head unit and cd player to the amp
……… you can see my problem...….