Can someone tell me why I can get an "Auxillary" mode on my 2003 coop with a CD53 R50 Alpine radio? Manufacture date is Jan 2003

I have an aux kit for my Ipod and have it all hooked up but can't get it to play? I only get FM,AM, and CD modes.

 

Might be too early ... but also, it only displays AUX if it detects the cable/connection. So a wrongly installed kit won't show AUX, even if the HU is compatible.