It took me some trial and error to get it done. First downloaded map and install, no response from head unit. Second try, same thing. Put USB back to PC and found out not enough space for map. Then formatted USB (16 GB as recommended ) and downloaded map again, it worked. After installing, I formatted USB just for next time. Not sure how many years we get free map update, thought some said five years. Those who know can contribute. Hope this helps.