Hi Neil,

Thanks for your response. Unfortunately don't have a PC. The Garmin Apps I have are BaseCamp, Express, MapInstall, Map Manager and WebUpdater (I don't have MapUpdater not sure there is a Mac version of that?. I see what you mean Map Install is only installing City Navigator Europe NTU 2015.3.img and a long string .gma file which I guess is the un-lock code.

i guess I can resort all the files to the internal memory (I have a full back-up of the original) then move the maps to the card (I guess I have to rename gmapprom.img, gmapprom.gma, gmapprom.uni to gmapsupp.img, gmapsupp.gma, gmapsupp.uni also do the .uni files have to be in the same directory as the map or do they stay on the Nuvi?

I was hoping to have a Garmin App do the install to the SD card so that when I download 2015.40 from the Garmin site it goes to the SD Card. If I manually copy the files I'm not sure how it can do the update as there wouldn't be enough room on the internal drive but there wouldn't be a recognised install on the SD card?

Thanks

PS anyone know what map files gmapbmap.img and D2249750A.img are?