thanks catymag.
I tried and I think its not working, may I know if my file and folders are correct?
img file: Computer\nüvi 55\Internal Storage\Map\City Navigator North America NT 2015.3.img
JCV file: Computer\nüvi 55\Internal Storage\Garmin\JCV\D3836110A.JCV
or there are any files that I'm missing? my Garmin is 55 LM and localized in Indonesia.