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Maps to a GPSMAP 66st?

Started by TAC57, August 14, 2020, 03:13:41 PM

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I've followed some of the tutorials but am having a hard time loading a map into my 66st.  I'm running Basecamp (v 4.2.5) and MapSource (v 6.16.3).

Just looking to install some Michigan maps of IR.



You need to tell us a lot more. Did you try to install the map in the GPS internal memory or on a card? If a card, how large? How is the card formatted? Does the card have other maps on it? What files/folders are on it? What are the size of the files? What shows on the map setup screen on the GPS?

Can you view the map on your computer in Basecamp and Mapsource? These two free programs are very useful for troubleshooting/managing maps.


Hi Boyd, from your reply and the number of view of my message I'm super happy to see this site is very active, thanks!

As far as your questions, I've attempted to install maps on both the 'Internal Storage' and 'User Data' under Devices | GPSMAP 66ST in BaseCamp.  I did this by right clicking on the specific folder and selecting 'Install Maps on GPSMAP 66ST'.  This then brings up MapInstall showing my GPSMAP 66ST with the message 'No unlocked maps were found for this device.'

My card is 16GB that I've formated in Windoze 10.  It shows up in Windows explorer as 'GPSMAP 66ST (F:)' while my 66ST shows up as 'Garmin GPSMAP 66ST (E:)'. Both drives also show up in BaseCamp under Devices.  Only thing on the card is an Id.txt file and a Garmin directory with a SQL sub-folder.

The Map Setup | Configure Maps screen on the 66ST only shows two maps, Worldwide DEM Basemap NR and Topo US & Canada v2.00.

I don't see any maps on my computer in BaseCamp or MapSource. I think my problem is in installing maps on my laptop computer where MapSource or BaseCamp can find and recognize them.  I've install a Michigan topo map to my laptop.  With MapSource I go to the location D:\Garmini\mitopo11 which lists a 1227A.TYP and a bunch of *.img files and it doesn't want to open any of them.


If you can't see the maps in Basecamp/Mapsource, then they were not properly installed. You cannot "open" Garmin maps. The installer creates files in a special location that Garmin's software can access. These are "system files" that are not supposed to be accessed by a user directly.

However, it sounds like the files were put on your computer. I suggest you try using Mapsource, which is easier to understand. See this tutorial.

I assume you already ran the installer. Step 2 shows how to choose a map from the dropdown menu. Can you do that? If not, then the map was not properly installed so try again and just use the default install location, don't change anything there. If it still doesn't work, not sure what else to say, maybe try a different map?

But if you can see the map, then use this tutorial

Does Mapsource find your GPS and show the window like the tutorial? If this all works, quit Mapsource and look at the card in Windows Explorer. A folder named Garmin should have been created and it should contain a file named gmapsupp.img. That is the map file. One important thing, the card MUST be formatted as FAT32. If not, then everything will look OK on your computer, but it won't work on the GPS.


Boyd your magic comment was "use the default install location"!  :-) As long as I didn't change the default directory of the maps I downloaded they all showed up in BaseCamp (and MapSource) and I had no problem sending them to my the 66st microSD card.  Go figure!  With File explorer I see the 3 maps on the SD card in the GPS.

I guess once the maps are installed in my GPS I can go delete the map folders that are scattered around my computer. Would be nice if changing the default directory actually worked since the let you do it in the install process.  :-)

Thanks for all your help!


Hummm....   MapSource said it xfered the maps to my GPS and I see three .img files in the Garmin subdirectory on the SD card in my 66st.  But after I uninstalled the the three maps I downloaded from my computer I can no longer see them when I plug my GPS into my computer from BaseCamp.  I would think they would still show up in BaseCamp from my User Data folder just like all my waypoints and other stuff that is in my GPS. 

When my GPS is unplugged from my computer I can still see the maps from my GPS.


I'm a bit confused. How did you "uninstall" the maps from your computer? You can't just delete the files, that may create some problems. Most gpsfiledepot maps use Garmin's old format where the Windows registry contains important information that is needed for each map. If you delete the files, the registry data will still be there and will probably confuse Basecamp/Mapsource.

Garmin no longer uses this old format, but most people here do. The new format (gmap) does not use the registry. Each map should include an uninstaller that takes care of removing all the files and registry keys. It should be in the same folder as the map files, you can just double-click to run it. Should also be able to uninstall from the Programs control panel in Windows 7. Don't have any maps installed on my Windows 10 machine yet, but I assume the uninstaller would be in the Apps settings.

Alternately, use the program I mentioned earlier. It can uninstall maps for you. This is probably the easiest way:

Just to understand... do you want to uninstall the map from your computer, but still be able to access it in Basecamp when the GPS is connected, like a "real" Garmin map? GPSFileDepot maps typically can't do that. But that other Javawa program can do this. There is a option called something like "visible in Basecamp" that you can set for each map with that program.

One other thing - if you use Mapsource to transfer maps, the file will always be named gmapsupp.img. Therefore, a new map will automatically delete the previous one you installed. You must manually change the filename to prevent that. For example, after sending with Mapsource, change the name of the gmapsupp.img file to michiganTopo.img (or anything you want). Then repeat this for each map you send to the gps.


I uninstalled from the Windows App menu.  I figured this was required because something had to be in the registry.  BaseCamp somehow knew the default directories for all these maps.


IMG files contain a bit that determines whether the map on the device is visible in Basecamp.

Maps installed with Basecamp are not usually visible because it assumes they will stay in Basecamp.  But if you've removed it from your desktop device then it will not be visible.

But there is a javawa utility (Device Manager, iirc) that allows you to make it visible again.


Quote from: jolly47roger on August 17, 2020, 07:34:59 AM
But there is a javawa utility (Device Manager, iirc) that allows you to make it visible again.

See my post above... ;)