How do you switch between the head unit and the OEM 6-disc changer (what button do you press)? Or does this just happen automatically when you press a button on the changer? I am basically just trying to figure out how the stock head unit reads that you want to switch to the changer as the music source. Hope this isn't too vague...

 

The Mode or Source button switches the CD player on. When you forst power the stereo on, it sends a message on the data wires checking for a CD player. If the CD player answers the stereo will let you access it. If there is no answer you won't see the CD option.

 

Thanks!