ACC out on my head unit died :(
Hi all, my project is a little lower-tech than most of y'all. I'm just trying to use a microcontroller for more sophisticated control of my factory head unit. I was powering the micro off the ACC line at the back of my head unit (normally for CD changer); this worked fine for a few months but now it seems to have died. Head unit still works fine, but the ACC out line from the back is now floating.
Any thoughts on how I managed to kill this? Any hope for fixing the head unit itself, or should I try to pick up ACC somewhere else? I guess this time around I should set it up to run off the BATTERY line and use a transistor to switch on ACC to be safe, but I really don't understand how I managed to overstress the ACC line with a micro in the first place...
Head unit is 2008 Corolla Factory: A51813, Panasonic 86120-02430.