This happened to my 2014 Journey Limited in April right as the 36k warranty ended. I called Garmin and they told me that there is a known issue with the memory becoming corrupted in the NAV units (On what he said was many many units). Also on a side note Garmin said that they did not make 2014 NAV units for the Journys and that the dealerships were installing that option with 2013 units at the dealership. Garmin had notes that the issue had been escalated to Chrysler engineers and the answer that was given to Garmin was to take it to a dealer. I called the Chrysler warranty to see what they would do and all they said was call them back once it was at the dealer. The dealer tried the update and of course that didn’t work then it turned into the unit would have to be replaced for a total cost of $600.00 for parts and labor since I was out of warrant by 150 miles (Which I thought this was iffy since I priced the units online for $1200 to $1500 come to find out they are using factory referb units as the replacements). anyway I called back the Chrysler warranty department and gave them the info I had learned and suddenly it was getting replaced for $100 bucks.
Thought you all would want to know what I have learned.