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Garmin Maps on uSD Card Transfer

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I have tried contacting Garmin directly with this question but Garmin do not seem to offer email tech support and rely on solving your problems by the FAQ for your device.  So I thought I would ask the Geocache Community for some advice.  Here goes.


I have recently purchased an Oregon 750T with the preloaded Topo maps, bluetooth, Wifi connection and live geocache features, all of which suits me very well and all work pretty well.

I also recently purchased the Garmin City Navigator maps as I use the 750 for automotive guidance and for the address search function (not available with the Topo maps).  At the time of purchase I had the option of a direct download (installed direct on the device internal memory) or via a uSD card delivered by post. 

Knowing that the internal memory space was pretty full and that my already installed 32GB uSD card would hold hundreds of photos, GPX, geocache files etc, I decided to go for the CN maps to be delivered by post on a uSD card.  My thinking was that i could just transfer the files over to the 32GB and then connect to Garmin Express for the activation process.

Unfortunately this is not the case.  It seems that the maps are locked to the supplied uSD card and do not work when they have been copied to another card or even direct to the device internal memory. 

This means that I can only use the 4GB card the maps came with.  Doh!

I noticed that one of the files on the card was called "ID" which when opening with notepad seemed to be a string array of hex numbers.  I would assume that as the map files are locked to the card, the ID file would be the serial number of the uSD card.  When the device boots up, it compares the ID hex file to the uSD card and if it makes a match, the maps are unlocked.


Ideally I want to transfer the maps from the original uSD onto my 32GB uSD.  Also, I would like to keep a back-up of the originals onto another card/drive so in the event of corruption or accidental erasure, they can be restored.  

I guess that if I could maybe get the serial number of my 32GB and update the ID file of the maps this could work?


Would anybody else have any ideas, thoughts on this? Many thanks


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Nope. If you wanted to transfer the files to your own card, why didn't you choose the option to download the maps directly? You would have had the option to install the map files to your SD card, but the map would be locked to your Oregon 750.

The upside is that the map you bought is locked to the SD card it came on, so you can use it with multiple devices, just one at a time.

The reality, had you checked in with us before making your purchase, we could have pointed you toward some free routable maps based on Open Street Map data that would do the job for you. Since the Oregon is likely not your main automotive navigation device, paying the high price for City Navigator just doesn't seem worth it, especially since it doesn't come with lifetime updates.

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It’s locked to a field contained within the SD card’s CID register, and it won’t be displayed in a file on the card.

The GPS device serial number is the equivalent of the SD card CID, but for the memory on the device, but expressed as decimal.


Only options are probably best for different forums, but one of them voids your Garmin warranty, and the other violates the EULA for the map data.

In Australia, we can bypass protection to back up purchased software, and data, but it’s not usually a friendly thing to discuss on the more official forums.

There are specific GPS forums for it though.


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7 hours ago, wing6rider said:

source of routable maps and would appreciate a pointer please?


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8 hours ago, wing6rider said:

Hi, the site I have been using for my maps - :  http://garmin.openstreetmap.nl/  - seems to have gone offline and may not be back soon.  I have been trying to find another source of routable maps and would appreciate a pointer please?


See the Maps page here for multiple listings!

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