When the dealer sold me the CD changer, they warned me that I would have to come in to the service department to have them program the head unit to understand that there was a CD changer attached. However, the first time I plugged it in and hit "CD" on the head unit, it just worked. The radio manual also gives some instructions on programming the head unit to make the random ("mix") function work the way you want (1-disc or all discs) on the CD changer. Be careful, though, because you have to go through the turn-on volume to get to the mix function programming, and the turn-on volume on my radio was 63 (all the way up) so it started playing at max volume as soon as I held down "scan" for 2 seconds. Maybe get a blank tape and play it when you're doing this process.