It sounds like you are trying to double-click, or otherwise open, an .img file intended for a Garmin GPS.
You shouldn't do this. Double-clicking tells your computer to "find the program that will understand .img files, and open this with it". But this .img file is not meant for a program on your computer. It's meant for your Garmin GPS unit. Assuming you have an SD card installed in the card socket for your Garmin, simply do this:
When your Garmin reboots, you should now have the OSM map displayed.
answered 25 Apr '11, 21:14
You can create a folder in your garmin device, name it "Map" then copy the "gmapsupp.img" file into it then it should auto load after.
answered 06 Jun '13, 10:02
Unfortunately it doesn´t work for me.
What I have tried: 1. Creating the folder \Garmin on my SD card and copying the "gmapsupp.img" into the folder 2. Creating the folder \Map on my SD card and copying the "gmapsupp.img" into the folder 3. Creating the folder \Map on the Garmin storage (next to the "Garmin" folder) and copying the "gmapsupp.img" into the folder
In neither case I can find the new map on my device (nüvi 255W). Source of my file: http://mapas.alternativaslibres.es/downloads.php (Chile OSM Base map)
edit: now I managed to do it with mapsource. Very good manual: http://www.nzopengps.org/index.php?option=com_content&view=article&id=3&Itemid=4 Probably my nüvi had problems with my SD card.
Download mapsource: http://www8.garmin.com/support/download_details.jsp?id=209 If you have problems installing it, unzip the .exe and double click the MSmain.msi