Nuvi 360 - Multiple GMAPSUPP files - How?

I don't have a nuvi 3xx series to test, but if I remember correctly, in addition to the 2 GB file size limit, that unit has some very restrictive naming conventions for .img map files. You can have a gmapprom and gmapsupp in internal memory (but its internal memory is limited so it doesn't help much to have 2 map files in internal memory). On the SD card you can have one gmapsupp. You might be able to have one gmapsup1 on the SD card too, but I am not sure about that. I think that is the end of it though ... no more map files supported on that series.

I think we have discussed this before in another thread back when Garmin maps first exceeded the 4GB size and they split into two files. I am unable to find that discussion, but maybe someone else can find it.

Have you tried a larger µSD card?
My recollection - which gets worse every birthday - is the 2GB number is based on what the max size available was at the time of your device intro. If you can run a FAT32 formatted card in it, then you should be able to use up to 32GB. The size is based on the format the device can read. I used larger sizes than were specified in my older Nuvis and handheld units.

The nüvi 360 has been terminated by Garmin, meaning they no longer support it. If eligible for map updates it will no longer receive them.

Now that I've gotten the preamble out of the way here....

1. Your nüvi cannot see the card but the Mac can because - best guess - the SD card is formatted using a format incompatible with the nüvi. The card is I think formatted as NTFS or else whatever file system Macs use, which the nüvi does not recognize.

2. I believe the 360 is limited to one map on the SD Card: gmapsupp.img. Other names will not work, and the map must be in the root of the card. You already know that a single map file cannot be more than 2GB in size. Coupled with the 1GB of internal storage it's not possible to fit the entire map of North America on such an old unit.

3. SD or Micro SD cards with adapter larger than 2GB can be used, but no single file can be larger than 2GB. And since the naming is restricted to one name: gmapsupp.img, using a larger card is a waste.

Conclusion: time to put this device out to pasture. If you don't want a Drive 53 or a DriveSmart you can go onto ebay or Facebook Marketplace and get a decent used device for little to no money.*

*My 3550LM is proof of this: I picked it up for free locally because the previous owner stopped using it.

Thank you all for your comments on my quandry.

Larger SD - Not the issue. If I clone the card, I can drop the entire NA 2026.10 onto the card but due to the 2GB limit, the unit won't read it.

SD Card format - Card is correctly formatted as 32Fat.

My pseudo solution - I moved the last full Canada 2024.20 map installed in the unit onto the SD Card and renamed that map to the supp file name. With the unit now clean, I used MapInstall to select the canadian portions of NA 2026.10 and installed them onto the unit.

I did try to kludge together a solution by using MapInstall to select a portion of the US for internal storage (ie fill the unit) but anything worthwhile was too large. I thought I might be able to shoe horn the remaining US portions onto the SD card but that was also over the 2GB limit.

So I have a Nuvi 360 now over 18 years old (based on my membership here) that I will relegate to the junk drawer in the entry hall hallstand as an emergency system. As newer maps come out, I may repeat the process.

I've got a number of alternates GPS and having replaced a 2003 Honda Element in Dec 2024 with an Hyundai Ioniq 5, my wife will be using the in-dash Nav system.

Cheers, all

Bob
Ottawa (not the one in Illinois)