I'm driving a 2012 Prius PHV with just over 300,000 miles on it. With the exception of having to replace a catalytic converter that went bad (i.e., not stolen or ruined in such an attempt) several years ago, the car has done great mechanically all these years and miles. Recently however, it has started to have some "weird" electrical issues. Sometimes when I start it it appears as if the accessory battery has been detached (the EV mileage range indicator reads 14.1, the address book in the navigation system is unsorted, and other anomalies (including a new one a couple of weeks ago - when started the navigation display displayed what looked like a hard disk drive animation and had a message that said something about loading the system). However, the battery has not been disconnected, and the car starts up and drives just fine. I'd suspect a short of some kind, but given it otherwise starts and runs okay, having a short that only happens when it sits in the driveway seems a bit unlikely. (I have checked as best I can without taking things apart and I see no sign of rodents or other creatures that might be eating/jiggling wires... but if no one else has any ideas I might have to go with this possibility.)
That's exactly what it does after power has been lost, so somehow, some time, that seems to be happening.
Check with the dealership for a software/firmware update that may take care of that problem. Also get your 12V battery tested. Good Luck....
