Quote Originally Posted by vantec21 View Post
Actually lane assist works if the file is on the SD card. Just has to be in the Garmin/JCV folder for the lane assist (.jcv) and the 3d building files can be in the Garmin folder. I confirmed this on my Nuvi 1390T device and it read the maps/lane assist directly from the SD. My model doesn't support 3d buildings but you can tell it's working/reading as the areas have boxes where there is 3d building support. Hope this helps!
If you put the lane assist file in the memory card under Garmin/JCV folder, did you also have to delete the original file in the gps unit?