Thread: Nuvi 66LM firmware rollback

I agree 100% regarding preboot difficulty generally when using the 'screen hold' method, however it's often overlooked that most healthy [not 'bricked'] units can easily enter preboot by simply holding the battery symbol for 5 or 6 seconds to access the hidden menu which in fact performs a boot-block. The unit is therefore in preboot for all intents and purposes and will stay that way indefinitely, until the menu is exited or the unit powered off, thus allowing RGN flashing with Updater.exe to be done without any haste. I added that as a note to [Only registered and activated users can see links. ] a while back because i was surprised just how few ppl knew about it, including some reasonably experienced users even though you mentioned it prominently in the [Only registered and activated users can see links. ], and it's also mentioned other places in here too.

In a healthy unit, it's absolutely both bullet-proof and fool-proof to remove gupdate.gcd if present, enter preboot thru hidden menu and then flash upgrade or downgrade version as XXXX01000xxx.rgn with Updater.exe because it reduced chance of bricking to zero in my experience with hundreds of such flashings.

HaHa! Thanks for being honest, no need for new topic but thanks for that offer too.
About beers, way too far from Moon to Earth and your brewery is probably shite up there anyway, so drink 'em yourself [btw, i thought you were probably Irish being as you said [Only registered and activated users can see links. ] so it would be all quite understandable actually ]. I personally am partial to a drop of Jamesons if the Scotch runs out t'tell t'truth t'ough [but can't speak for Caty ......]. Anyway, you're probably actually just from one of the the many places in NA named 'Erie', probably PA or somewhere pedestrian like that, seeing you have an LM unit and were wanting to load EU map. So just make a donation to the forum if the mood has really taken you but no pressure though.

Hate to tell you this now, but the [Only registered and activated users can see links. ] is more suited to your unit because there's no JCV file compatible with your 65 for the non-unicode NT map. Matters naught if you don't want to use JCV or unicode characters for search though

hi Neill i tried Garmin City Navigator Europe NTU 2015.40 unlocked but it tells me cannot unlock map. are 55 units not supporting ntu unlocked maps ?
also there is no jcv for my device when i use nt map?
regards TM

Sorry, i wasn't clear about that. I think to use the NTU you will need to change the code page of the map from 65001 to 1252 with [Only registered and activated users can see links. ]. I don't have a recent device like 5x/6x to test this though. If you want JCV, try doing that CP change and if then you also want unicode features there's another trick, see Caty's post #20 here: [Only registered and activated users can see links. ]. There's no compatible JCV file for your 55 with NT EU, only available for the unicode version.

You have only one garmindevice.xml in Garmin folder. You must look at it.
Example:

-<Model>

<PartNumber>006-B1749-00</PartNumber>

<SoftwareVersion>430</SoftwareVersion>

<Description>nüvi 66</Description>

</Model>

<Id>XXXXXXXXXX</Id>

@Akram
Put the unlocked map on a microSD. It can go in a root folder named Garmin with file name gmapsupp.img only, or it can go in a root folder Map as any_name.img, e.g. CNNT_NA_2015.10.img or any other descriptive naming.