I wasn't able to find a list anywhere showing which tire sensor measured which tire. By inflating the tire one at a time, I found that they are: ID1 Front Passenger Side ID2 Front Driver Side ID3 Rear Passenger Side ID4 Rear Driver Side I hope this helps someone. I may even look it up here myself in future.
Maybe that's what you have now, but not universal for everyone. Plus, once you rotate the tires, they will not be staying at the same location. ID is sensor-specific and the car does not know the location of four sensors.
I used the same selectively-let-some-air-out trick to initially identify which ID went with which position. I put them in a list in a text file. Since then, whenever I rotate the tires, I just permute the list to match. If I go somewhere to have the tires rotated, I can compare to the list to confirm it really happened.
The ID slots will correspond to different positions after the rotation. Each sensor permanently has its own sensor ID number. The sensor is mounted in the wheel and goes wherever the wheel goes. In the tire pressure ECU, there's a level of indirection: the ECU can remember up to five sensor IDs (in case you add a sensor for the spare, not there from the factory), in slots named ID1 through ID5. In each of those slots you'll see the actual several-character ID of the sensor that was registered in that slot. There's no special meaning to the five slots, they just have the sensor IDs that have been registered with the ECU, in whatever order they were registered. So if slot ID1 has sensor id 1234abcd in it, and that's your right front at the moment, and you then do a front-to-back rotation, slot ID1 will still have sensor id 1234abcd and it will be the right rear wheel.
So the tires are ID'd but not the position. Then tires will need to be marked to the ID so you can keep track of the tire position when you rotate or replace or get TPMS light.
Correct. But for a dumb TPMS like on PRIUS which does not show each tire pressure, it does not matter. The car knows which sensor is sending a low-pressure signal but the car has no way to display this information to the driver. For my Nissan that has TPMS positional information display, the sensor location is relearned automatically after a tire rotation. However, I believe there are some cars that require TPMS sensor ID registration after each tire rotation in order to show the correct location on a screen.
More on this we just figured out. If you have a low tire pressure warning for too long a time, then the you get a DTC set. If you inflate the tires to the correct values, the sensors report the correct values, but the light on the dash does not go out until you clear the DTC. If you do not know this then you think, like I did, that a sensor has failed. They all worked when I looked through the ODBII port. I just had to clear the code to turn the dash light off.
I never had a low-pressure warning on my PRIUS, but DTC must be specific to low tire pressure not on TPMS system error. I keep my summer tires with the sensor off of my car during winter. Winter tires without the sensor will keep the TPMS light on all winter long, but as soon as I put the summer tires back on the light goes off.
That button is for telling the TPMS "look at the tire pressures I have now, those are the pressures I want, set the warning threshold some % below those." So, any time you have changed your mind about what pressures you want, that's a time you'll correctly use that button. And any time you haven't changed your mind about what pressures you want, but you just have something going on with the TPMS and you wonder what the button does, that isn't a time to use that button. If you do, then (a) it probably won't do what you're hoping it'll do, and (b) it will set your wanted tire pressures to whatever they happened to be at the moment it didn't do what you were hoping it'd do, and that'll be something you weren't hoping it'd do.
