It does not function. Every so often the map will reappear, but It requires a new reader. To fix it will cost 2250, so since that it about what I paid for it, I guess it needs to be replaced.
I have a 2010 Prius with factory installed navigation. It stopped working a few months ago, and I am not willing to pay 2500 dollars to fix/replace it. I wondered if anyone else has had the same problem.