I don't think any version of Garmin devices provide turn by turn unless you download the base maps. Either the Open maps (free) or the Garmin (paid) maps. Otherwise if you create a course, you are just riding according to GPS locations. Your device doesn't any have knowledge of GPS coordinates to streets, unless you download the base maps. Then the GPS device just makes assumptions that when your course says turn at a given GPS location, it locks on to the closest known GPS location of the streets defined in the base map.