Thread: Unlock map (to move from one Garmin device to another)

You cannot use BaseCamp or other software to 'trim' an already compiled IMG file. You can load the map data to your PC via GarminExpress and use MapInstall to send a reduced size IMG to an SD card, unlock it with gimgunlock and then transfer it to your 205. However with latest firmware loaded, your nuvi 205 can see IMG files of up to 4GB (with old fw the size limit was 2GB). So just use a 4GB SD card for your 205 and it can use the entire North American map. Best not to put unofficial unlocked maps in it's internal memory anyway, if the IMG is corrupt it could 'brick' the nuvi . On a media card it doesn't matter, remove the card and the device behaves normally. Post again if you need more info.

BTW, because nuvi 205 doesn't have additional protection over GMA an older version of the unlocker should have worked unless the one you found was the very first one limited to the ability to unlock IMGs up to 2GB in which case it wouldn't have worked at all with an IMG over 2GB. It's more likely your original attempt was slightly corrupted in some minor way, check the IMG in GMapTool ('Details' or 'Info' tabs) if you can be bothered now:

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I've been getting success on the 205, but the procedure totally failed on the 350NA. The only procedure that worked on BOTH units is unlocking the official file with the more modern version of gimgunlock and putting as gmapprom on the internal memory. I suspect the over 2GB file issues with some units, but the trick I found is you can put a 1GB dummy file on the 55LM unit and then they offer you the option to download a trimmed map via Garmin Express for your region, which you can then unlock and have available for the sub-2GB units. This way you don't have to worry about using an SD card.

But what's this I hear about bad maps bricking the unit? In my experience the maps just don't get detected or don't work right if they're bad.

Any faulty file is capable of soft-bricking a device. That might be a GPI, IMG or VPM file most commonly. The thing about IMG files is that they are more complex than most other files and therefore more prone to corruption. The map might load but not function properly or not even be detected. A really bad map likely cannot be loaded on boot-up, depending on what's wrong with it the device will either ignore it or stick on the logo screen when displaying 'Loading Maps' message. In the latter case if the faulty map is on a media card simply removing the card allows the device to function. If it's on the internal memory then cure firmware usually must be loaded to allow Mass Storage Mode to work so the file can be removed.

Yes, certainly Garmin Express offers that option of a smaller regional map to be loaded directly to the device. The function i was referring to is entirely different where you choose 'Map Options' on the device's first screen in GE and then load the mapping data to your PC so you can then use MapInstall (directly or invoked via BaseCamp's 'Install Maps' option) to compile a custom map to send directly to an SD card. The resultant IMG file is then unlocked and you must remove any other files such as GMA and/or UNL files also generated along with the IMG. The SD with the unlocked IMG can then be used in any device without protected firmware such as your 205.

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P.S.: Your reference to "350NA" is I'm guessing about "nuvi 350". Some legacy devices still have the old FAT16 2GiB file limit, nuvi 6xx and 3xx are included in that. This is a different problem to devices having a limited internal flash memory. The 2Gib file limit affects IMG file size because those devices only understand FAT16 so can't read from a card formatted in FAT32 using larger files. That's an imposed limitation of the File Allocation Table itself although it can be changed to the FAT32 limit of 4GiB by updating firmware. Garmin did that for some devices, your nuvi 205 for instance, but they haven't issued a corrective fw for nuvi 3xx and likely never will now. The reason your nuvi 205 can read larger than 2GiB map IMGs is because it's running newer FW:

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Garmin added and announced the ability to see a second map (named gmapsup1.img btw) on SD card in nuvi 2xx V5.10 in Nov 2012 but they also quietly allowed the the use of IMG files up to 4GiB size i think in V5.00 about a year earlier. Some information about both features in this old thread: [Only registered and activated users can see links. ].

Thanks, I'll keep that in mind if the current method I'm using causes me trouble. I'm not THAT worried about the remote chance of a map bricking my Garmins since my Garmins are old units bought used/"broken" for $5-$10 a piece. I tested the method on the cheapest units first and when they worked fine, I did it on the rest, so I assume I should be OK.

But what's the process you use to unlock a map, once you finish in BaseCamp, so BaseCamp allows you to select the SD card or the Garmin? Don't they ask for unlock codes?

Once you've downloaded a North American .GMAP folder using GarminExpress linked to a device (say your nuvi 55LM) there are codes also downloaded and installed limiting the use of that map data to compiling IMG files for only the device/s authorized under those codes. So if you then hook up your nuvi 205 for example which has no map update entitlement you're not going to get a usable map unlocked for the device. Even if the GMAP folder has been unlocked for use by MapInstall the resultant IMG will still be locked so you then need a modern IMG unlocker. Search for "gimgunlock V0.04", you won't find it on this forum. Quite frankly the simplest way is to send what you need to an SD card where it will be loaded as gmapsupp.img in a Garmin folder, remove any .GMA files also loaded and then run gimunlock on the IMG and it'll be usable in any device without modern protected firmware.