When traveling through a long tunnel the GPS loses signal, ...of course... and the screen goes to blank grey. After exiting the tunnel the screen returns as normal but looses the route guidance. So you have to pull over to a stop and restart route guidance . This can not be normal can it? Dan
I'm pretty sure it's not normal. I have a tunnel that I go through on a regular basis and the GPS gives no indication that it has lost the satellites, though I'm sure it has. Modern GPS units seem to anticipate where your location should be and will give the appearance of maintaining a track for a short period of time even when it has no satellite info. (I hate that.) I have been in a deep canyon when the GPS lost its statellites for a fairly long period of time (a minute or so) and the GPS eventually displayed a question mark to indicate that it no longer could even guess at my position. But, a minute or so later the satellites were reaquired and the GPS started tracking properly again. There was no need to restart route guidance.
I've turned the car off in mid-guidance and turned it back on and it picks up right where it left off.
Some systems - I know - use wheel speed to guestimate position during GPS signal loss. Unfortunately, other than the GPS signal - I don't think there is a standard as to how to calcuate routes, etc. So everyone has a different method..and no two are alike.
It should work. Maybe yours has a problem Toyota should look at. I would think it would do a "recalculate" at least. Mine does.
I have the navigation speed lock override and it essentially tricks the GPS head unit into thinking your speed is zero so you can use the menus while in motion. I notice if I leave it on while in a guided route the GPS tracking completely loses dead reckoning (which it seems to depend on heavily) and goes crazy. It'll think you're stopped sometimes and then sometimes it will know you've changed position but while trying to recalculate your position it gets confused because it's GPS sensor tells it it's moving but the speed sensor thinks your speed is still zero so it will constantly try to recalculate and have you all over the map. If I turn off the speed lock override the GPS is absolutely solid, and with dead reckoning it does a really good job of keeping my position even when I go somewhere it's likely not getting a good signal like in tunnels, downtown etc. Sounds like something is keeping the dead reckoning from working properly in your system.
Thanks for the input, It does sound like something is not right..even a $50 GPS can get it sorted. We had a second GEN. prius that had no gps issues that I can remember. Dan
Where did you encounter the issue? Does it happen all the time with that location? Are you using the SW 2.1.0? U should log a complain. Dead Reckoning today used GPS, Speed and Gryro (2 axis or 3 axis). yes a $50 unit does GPS only, and will always recover when it gets right GPS. do you want a car that has the option to do GPS only much like those PND?
