When I calibrate, as per page 251-252 of the Nav manual, after swapping my 17" wheels for 15" wheels, I see a message to the effect "entering calibration mode" and then, after just a few seconds, it reverts back to the Nav screen. Does anyone know what's happening during the calibration?
I haven't swapped out my wheels yet, but I'm guessing that it's comparing tire rotations with GPS distance to compute the new rotations per mile. That would improve the dead reckoning and also time to destination accuracy.
Depends on what you mean by "necessary." OK...I'm still a noob to Priusdom, but I'm presumming that you'll get some kind of fault generated by the instrumentation of this car when it can no longer communicate with its OEM TPMS sensors... If the light doesn't bother you too much, then no....the OEM TPMS aren't "necessary" to drive the car. A 1" piece of black electrical tape will "clear the fault"... There's threads out there somewhere that deals with this topic such as this one: http://priuschat.com/forums/gen-iii...ns/77254-idea-fool-tire-pressure-sensors.html I won't beat you up about the search function, since I hate self-appointed forum-nazis. Good Luck! Let us know how it shakes out.
As RodJo said it tells the nav system to recalibrate the dead reckoning function which it should do next time you drive. It only does the nav, not the odometer or the speedometer and has nothing to do with TPMS.
The problem with the Toyota TPMS is that the 4 wheel sensors are entered into the computer and can only be changed with Tech Stream software and your dealer will want to charge you to do so. As far as I know tire stores, at least in this area, can not change them. This means if you have winter tires mounted on their own wheels you will get a TMPS alarm. You can ignore it or cover it with tape, as mentioned above, and go without TPMS in the winter which is what I would do. My opinion is that TPMS is more trouble than it is worth if you check your tires with a gauge every couple of weeks and do a visual check before you drive.
