Does the Cadillac CTS 2008 have a aux for music ?

It should have both aux and USB. Either below the radio n heater controls in the storage compartment or it will be in the center console.

There is an AUX button on the console, but that doesn't mean there is an aux port. The aux port is an option offered by Cadillac. If you didn't opt for it the aux you still get the button on the front of the console. If its not on the radio, in the glove-box, or in the armrest... its not there, and you will need a kit like an Isimple IS77 to add the aux in. http://www.amazon.com/gp/product/B002IY598O/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B002IY598O&linkCode=as2&tag=bafmin-20&linkId=G77HMN2O6TNKGQKO