@flagmax
Thanks for the suggestion, but your musing is correct that StreetPilot 2720 [and earlier] are different. I agree that nuvi 2 series and circa have the internal files system on rgn48. Recent units have it on rgn83. No problem to write back with txt commands on card too, even copy the entire internal file system with copy dir, some 'semi-bricked' units can even do that using kunix's modded boot method depending on the cause preventing the boot like described in [Only registered and activated users can see links. ] for instance. But unfortunately we can't dump regions from these older units [afaik] so no way to modify a region and flash it back as an RGN. The only regions' usage which i know for sure are rgn3 for basemap [see post #7], 49 for the primary map gmapprom.img and 50 for an OEM map gmapoem.img. Sendmap20 and MapSource/MapInstall write secondary map gmapsupp.img but i don't know to which region, maybe it shares region 49 with gmapprom.img, i simply dunno. I think rgn5 might be for boot on these units too. I'm very interested in your info about writing back the header for 48/83 on nuvi though, i thought 2xx/2xxW could have 48 erased but it wouldn't copy however that might be only 2x0/W, can't remember. You should open a topic about that header stuff separately, i'm sure i won't be the only one interested in it.

The point for me is that this is a whole new ballgame and anyone else used only to dealing with nuvi series 2/3/6/7 and later. I happy to fumble in the dark here, because i have several SPs, an AU 310, a US 2610 and 2 x 2720s also US [one of which suffers from an untraceable and unpredictable intermittent screen freeze so i'm prepared to play with it, torturing it to death if need be. I only paid a couple of bucks for it on eflea a few weeks back, listed as for parts only/not working for the sole purpose of attempting to change the basemap. This thread reminded me of it and prompted me to find a way using updater.exe now i've managed to do that, so i already owe our New England friend technit [i assume his 'South Shore' is the Massachusetts South Shore].

I know 49 can be flashed with a new map, no matter how small it will erase the existing primary map in a healthy unit using command line to invoke WU. In my US 2720 i overwrote the onboard 2014.20 lower 48 with Raratonga as reported above, and have now overwritten that with AUNZ 2015.30 using the same method. This is what our MA friend is now game to try but i don't think it'll break anything even if it starts but fails to flash fully or aborts. He already has a corrupt map on rgn49 anyway. Where Sendmap20 has a command to erase the secondary map via it's GUI and i think it can also be done with the command line [x:/Garmin/Sendmap20.exe -e] but i don't think WU has a working 'erase' command like that and can only overwrite the primary map via it's GUI or command line. His unit can't be seen in WU's GUI, so i guess it probably won't find it if invoked by command line either but that's worth a try.

As i also reported above, my kindergarten-level hex manipulation skills have fluked me replacing my unit's Americas basemap with the Pacific one, but i'm stuffed with writing to 49 using the Updater.exe/RGN file method which we know will work on technit's unit as he could successfully flash fw with updater. I guess the fw is being written to rgn14 [but again i dunno] what is important is that it can write regions at least. So, provided his rgn49 isn't damaged and is only corrupted by an incomplete map image aborted mid-load, if we can find a way to erase it or overwrite it with a good img it should boot normally. I hope your advanced skills can help with this, i need somebody to work out how to hex edit a detail map RGN file for rgn49 the way i've lucked-in with a basemap for rgn3. I'm prepared to risk my sick 2720 to test anything first as i only bought it to find a way to replace the basemap so it's already served it's purpose and is useless for normal use because of the screen freeze. I think you can and will help with this so please excuse the quick update on the differences between these early automotive garmims and the later ones.

@technit
The Cavalry's arrived. Hope you don't mind that it's from sunny [but formerly Confederate] CA, or maybe even from your northern neighbour CA depending on whether 'Ca' means California or Canada, lol! Maybe we might get others helping too, but this guy flagmax know's what he's doing and will be teaching me stuff about these old things within a few nanoseconds. While he's gathering his thoughts, let's try this:
  • Hook the unit up to your PC
  • Extract this pack to somewhere convenient, your Desktop will do, to find the file named 'update_detailmap_2720.BAT' and the Rarotonga map named 'gmapprom.img': [Only registered and activated users can see links. ]
  • Go to your C drive and check you have WebUpdater in the root folder Garmin there. Open the WebUpdater folder to see it's the actual program in there including importantly the file WebUpdater.exe. If it's not there you'll need to find where it is on your PC and move or copy the program folder over to the Garmin folder.
  • Move or copy the small gmapprom.img over to C:\Garmin [don't put it inside the WU folder, just in the Garmin one]
  • Go back to the update_detailmap_2720.BAT file and double click it to run it. This command will run: "C:\Garmin\WebUpdater\WebUpdater.exe /upload_file rgn=49 path=C:\Garmin\gmapprom.img -autorun usb /i" and hopefully after the DOS box opens it will be quickly followed by WebUpdater's progress window which should very quickly load the tiny map to overwrite your corrupt primary one. If successful the unit will reboot normally and you can then load your NA map again with MapUpdater.


I fully expect that this may not work. If so, don't despair. There'll be more refined things soon to try no doubt. Try to get screenshots of any error screens if it fails though ['Ctrl' + 'Print Screen SysRq' keys, open Paint and press 'Paste' button]. Good luck mate!