I appreciate the thought, but no. This was not a simple case of the nav seeing a road closure and tellng me to go around it. This trip was well past the rains and the highway was indeed open. Somewhere north of Cambria, the nav went "cafluey" and the entire map went blank. Not only did the roads disappear from the map, the entire screen was blank and became a solid grey color. It was as if the nav was completely blind. My wife and I were joking that if we followed the actual directions the nav was telling us, we would have driven into the Pacific Ocean. The nav did come back once we were close to Big Sur and, I am guessing, back in range of a cell tower.
Shortly after this happened, I posted about it on TMC and other drivers reported similar experiences when driving through areas with no cell reception.
Just something to be aware of when planning trips, esp in areas with no cell coverage.
Tesla Navigation is multiple layers integrated together. The car keeps a built in offline map that’s just sequences of roads and turns. That gets overlaid on to a graphical map that comes down from the web, and it looks up Points of Interest online.
The car knows where the road is and where along a road it is (assuming GPS is working,) without the cell connection, but won’t show anything but the path zig zagging along without the cellular data.