Aftermarket head unit, car "forgets" settings.
I installed an aftermarket double din. I have even relocated the head unit to the trunk. Everything seems to work fine, except that when the car sits for more than 6 hours it forgets everything as if the battery was unplugged. It forgets the time, the date, the mileage, basically everything that would be reset if you unplugged the battery. Strangely the car doesn't do this when it's restarted 1 even 2 hours later. Anyone have any ideas? This is perplexing me.