Thread: Nuvi 66LM firmware rollback

Originally Posted by tattooman

quick question in GarminDevice.xml is version number <SoftwareVersion>430</SoftwareVersion> .........

Yes, it's the Unit Software [aka firmware] Version number without the decimal point. "<SoftwareVersion>430</SoftwareVersion>" displayed in GarminDevice.xml means that the device is currently running V4.30 firmware.

do i need add it to rgn name or version number of Nuvi65&66_220.gcd firmware file example 174901000220.rgn? ......

You should name the rgn file exactly as explained in Post #2. The last 3 numbers are not so crucial but are helpful in identifying the content of the file. If the first 4 numbers do not coincide with the unit's actual HWID, Updater.exe will return a message saying there are no updates for your unit as protection against flashing firmware which isn't suitable for the unit. The middle '01000' determines if the HWID identification occurs, it it is absent or even lacks 1 of those 5 numerals the flash will occur without regard to compare of actual unit HWID to the HWID in the intended firmware so it's crucial that the naming convention be respected. For example, naming of OUT.rgn is commonly used for purposes of cross-flashing by advanced users to easily identify such a 'non-complying' rgn file resulting in the HWID of the recipient unit being changed [rather than naming of XXXX0100xxx for instance, as the lack of a zero might be easily missed]. Unless you know exactly what you're doing you should never use any other naming convention than XXXX01000xxx.rgn as per Post #2.

Also do i need change software version value in xml also?
........

Absolutely not. The xml is rewritten by the device upon every reboot anyway. Any change you make would be temporary therefore. These are other reasons to do it however which are totally unrelated to the specific matters here.