Is update to MacOS 10.11.x required to install maps on nuvi 3760T

Could you perhaps explain what you mean by going round in circles?


Which mapset is installed on your nuvi? What have you tried so far that hasn't worked? Where does it fail? What errors are you getting, if any?

It seems that I have tried everything and am totally frustrated.
There are no error messages. I purchased the Map Lifetime maps. The installation ends by stating in German that the good news is that everything is up to date. But in the car, the message is that the maps are old (2013). I've installed the communicator plugin.

Also two Garmin USB icons appear on the Mac desktop.

It's still not clear what you've done so far so let's take this in stages. Have you activated the map update? See this FAQ

http://support.garmin.com/support/searchSupport/simpleCase.htm?caseId={56c1f930-212b-11e3-f27b-000000000000}&kbName=garmin

could this be my problem?

From the console:
17.04.16 11:34:06,262 PluginProcess[1248] 6 GarminGpsControl 0x07e76108 _ZN3win5OsStrEv + 88
17.04.16 11:34:06,883 com.avast.proxy[554] Error connecting to 80.156.86.78: Connection refused
17.04.16 11:34:06,883 com.avast.proxy[554] SSL_shutdown(): uninitialized
17.04.16 11:34:06,883 com.apple.WebKit.Networking[685] CFNetwork SSLHandshake failed (-9806)
17.04.16 11:34:12,143 com.avast.proxy[554] Error connecting to 80.156.86.78: Operation timed out
17.04.16 11:34:12,144 com.avast.proxy[554] SSL_shutdown(): uninitialized

The map is nuMaps Lifetime Europe and the icon appears twice in the window to active. When I click to download Garmin Express the message appears HTTP 404 Error has occurred.

First of all, you need Garmin Express installed. Garmin seems to support all of the OS's that Apple still supports, so since you're running Yosemite, you shouldn't have any problems (Apple still puts out updates for 10.9 and 10.10 as well as 10.11). You should be able to get Garmin Express from http://garmin.com/osx, and it installs using the OS X Installer, so double click and follow directions. Second, get rid of Communicator Plugin; it no longer works and hasn't for years. Third, the IP address 80.156.86.78 is owned by Deutsche Telekom AG (open up Terminal and type "whois 80.156.86.78") , so it probably has nothing to do with this, but it seems you're using a proxy server, so you're going to have to sort that out if you're having trouble connecting to IP addresses (you may have to contact your ISP). It's been a long time since I last purchased maps from Garmin, but I do have Lifetime Updates for two Nuvi's, and I regularly install maps on my Mac Pro and the Nuvi's using (now) El Capitan. It worked under previous versions of the OS as well. So long as Express works on the OS, you should be able to do it.

Totally uninstalling and installing Garmin Express seems to have solved my problem.