Thread: Nuvi 58LMT "can't unlock maps".

@janch
Yes that'll work for sure unless it's a corrupt IMG (not identified in GMAPTool though) or he has a physical flash problem (unlikely). Regardless, because it's an LM device i'd prefer to sort it out without reverting to patching if possible ....
Nudge, nudge, wink, wink ... you know the problems that big-bang's patcher caused us in 2017 ...

@stevex
Did you try this?:

The other possibility is that one of the "old" GMA or UNL files from an earlier version map is interfering with reading of the current detail map. You could try removing everything from the Map folder except these:

Code:

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and/or this?:

You could also try removing all the present detail maps and their associated GMAs and UNLs then replace them on the device in their proper locations with the files you downloaded from GE via the "nuvi clone" SD.

Yes I removed all the old GMA/UNL files.

I also tried removing the new ones so it had no detail maps at all. Powering up and I no longer get the warnings but of course no usable detail maps.

I then let Garmin Express recreate the files by reinstalling maps. Warnings and errors back on power up.

I tried replacing those files with the ones from a "clone" SD card which GE had created maps on, same warning.

I've copied the newly created files from the device, SD and older back up and compared. The large *.img files are identical (same hash) but the .gma/.unl don't match. Presumably that's expected?

I am wondering if the unlock algorithm changed in some way that's incompatible with older devices: this one is from 2017.

If there are any diagnostics or other things I can try let me know. I'm pretty tech savvy but a noob when it comes to Garmin internals