A very dangerous condition exists in the navigation systems, apparently in all models of 2012 and 2013 Toyota equipped with factory installed navigation systems. The problem is that the system fails to produce a voice prompt for turns perhaps as much as 50% of the time. Failure of the voice prompt means that you must continually look down at the screen in order to know where and when to turn. I'm certain that this has caused many, many accidents and fatalities as well. There is a warning that comes up every time you turn the system on saying that watching the screen is dangerous and can cause accidents. I have taken the car back to the Toyota dealer I bought it from several times, and have demonstrated the failure to them. They acknowledge that the voice prompts are a sometimes thing. At my request, they tested another Toyota of the same make and model, and informed me that it had failed as well. I tested a neighbor's 2013 Prius C and found it to fail the prompts at the same intersections. I also tested a 2012 prius, and it failed also. The Toyota salesman tells me the the same navigation system is used in all but a few 2012 and 2013 Toyota models; so I'm assuming that this problem exists throughout at least all 2012 and 2013 Toyota but for a few that use a different system. All four of the Toyota tested, including the one tested by the dealer have failed to provide voice prompts at the same intersections.these are not newly created or remote intersections. One of them is a 6 lane arterial (ne164th ave & SE 164th ave. In vancouver, wa).the system has failed on freeway exits and in other cities (stevenson, wa, 54 miles distant, beaverton and portland, or, and longview, wa.) and in clear as well as overcast weather. I've used garmen and tom tom systems extensively without ever experiencing this problem before.

- Vancouver, WA, USA