Fairly new here. I'm using both a Zumo 660 and a Nuvi 3590. I've been trying to install my Nuvi maps into a OEM Dodge 430N HRB nav/media unit without much luck.

How can you distinguish between a locked vs unlocked map, I'll focus on the Nuvi maps rather than Zumo if that makes a difference? In an unlocked map, does the code (Info or Detail) shown in GmapTool, 2nd line up from bottom, show up as, U: 00000-00000-00000-00000-00000 or would this not matter? Not really sure if any of this makes a difference, just trying to understand.

So interestingly enough, my OEM unit will read the Garmin 2014.10 maps but will not read the 2015.20 maps... Are there major differences, i.e. formatting, coding, structure, etc, that Garmin did in the past year?

Thank you.