Not sure about that Peter, but I've solved the original problem :) It appears that when using the ACM in iPod mode rather than the CDC, one of the CDC discs is partially loaded. What I did, which I now discover I shouldn't have, is to attempt to eject the CDC cartridge when the ACM is in iPod mode. This confuses the CDC logic, throwing up a CDC error because a disc is partially loaded and so the cartridge eject is unable to complete. The error does not affect the ACM in iPod mode and so my iPod continued in blissful ignorance when I selected CDC on the radio unit. However, each time the ignition was switched on, the system polled the CDC, discovered the error and defaulted to the most recently used alternative source, until the CDC was re-selected with the iPod having been recognised by the ACM. What I should have done is to select CDC mode (ie de-select iPod mode) on the ACM and then eject the cartridge. When I did this, the partially loaded disc returned to the neutral position and the cartridge was able to eject properly. Dead simple when you think about it ;) To confirm, I reselected the ACM to iPod mode and, again, a disc was partially loaded in the CDC. Oh well... you live and learn :)