At what psi does the tire pressure monitor come on when the tire pressure is low? in other words, what psi does our prius consider "low" to notify us and turn on the TPMS?
I think I heard 25% below set pressure triggers a warning. If you want to reduce that you can temporarily raise pressure, do the reset procedure, the drop pressures. I've found it can be flakey; had the light go on, but pressures were fine. Raised them a bit anyway. Light went out, and didn't come back later, once pressures were set back to usual.
2006 I think it is about 26 psig....some Gen3 you can set this value I forget which years...see your owners manual
On Gen 3 anyway, Techstream will show you (if you pull up TPMS, live data display) the current pressure and current temperature in each tire, plus the low-alarm threshold for each tire. The only way to reset the low-alarm thresholds is to push the TPMS reset button after changing the pressures. On mine, when I had the tires inflated to about 38 and 36, pressing the button seemed to set the thresholds to about 32 and 30; that is, it set thresholds about 6 psi below what was currently in the tires. I wanted mine to give an earlier warning than that, so I inflated to 43 and 41, reset the TPMS there, then let the pressure back down to 38 and 36, figuring that way I could get a warning when just 1 psi low. It hasn't seemed to work exactly that way: the setpoints ended up more than 6 psi lower, so it wouldn't surprise me if a percentage is used, rather than a straight 6 psi. If that's the design, I guess it's something around 16%. Next time I reset them, I'll use a higher temporary pressure. Another thing Techstream will show you is the transmitter ID number at each corner of the car. This can be sort of an easy way to check that a shop really rotated your tires if they were supposed to, without resorting to more obvious tactics like chalking your tires ahead of time.... -Chap
For a Gen3, IDK (I Don't Know). For a Gen2, IIRC (If I Recall Correctly), the TPMS is triggered when a 25% variance is detected. The door placard says to fill the fronts to 35PSI, and rears to 33PSI. You are aware that you should check and fill your tires when COLD?! If the TPMS is properly RESET to 35/33, a trigger will occur when the front sensor reads 26.25PSI (35 x .75), or lower, and/or the rear sensors read 24.75PSI (33 x .75), or lower. It is important to perform a reset when you adjust air in any tire, so TPMS learns the new air pressuress; minimum four times a year due to the seasons. When a 25% difference in pressure (realistically a loss), is detected in any wheel, the warning light triggers. Pull over QUICKLY! Check each tire to see which one is loosing air, causing the TPMS to trigger. A screw/nail will be a likely culprit. Pulling over quickly is for safery and can mean the difference between a repairable tire or non-repairable tire, assuimng a puncture occured in the tread, and not the sidewall. You should read this to enhance your tire knowledge. How To Check Your Car's Tire Pressure and Inflate Tires | Edmunds.com Read page 443 of your 2010 owners manual. If you do not have the owners manual anymore, you can access it via Toyota.com. Here is a link for the 2010: http://www.toyota.com/t3Portal/document/om-s/OM47668U/pdf/OM47668U.pdf Kindly READ The Fahrvergnügen (Owners) Manual. Come to understand your car better and some features you may not know about. Also read the warranty booklet. Ignorance can be expensive as these people found out: Toyota Prius Battery | PriusChat
Correct..somebody explained it to me on a prior post, but I forget the details. I have TPMS reset on my 2006 too but it does not change the alarm value. But a few years of Gen3 the reset did change the alarm value. So I think many our discussions on this topic are rather hopelessly confused, as some people claim the reset value changes the alarm set point, which was true but only for like 2 years
What would the reset button be resetting, if not the alarm value? Since front and rear pressures are different, the need to reset after tire rotation is all about changing the thresholds associated with the different transmitter IDs, which have changed positions. -Chap
No...the tires all "leak" air (it permeates thru the rubber). If you really feel that way, you can go with Nitrogen (eg; COSTCO) but nitrogen still leaks just about 33% slower leak than air. This is because O2 leaks 4x faster than N2. So using N2 helps a little bit. For my bike tires, I use STAYFIL which is a very expensive, heavy gas that does not leak. It does make some sense for bike tires and the Prius compact spare I put some STAYFIL in there. Stayfill keeps your tires full and ready to roll | Stayfill
Good question. do not know what good it does. God knows I tried pushing it a million times when my TPMS sensor went bad, to no avail. When you have 4 good TPMS senors they transmit new data every 60-secs or so, so I never saw a need for the RESET. When your TPMS goes bad, let's say you are at 35 psig, the 35 psig stays in the Techstream value register for weeks sometimes before the 2006 anyways finally figures out it is not getting new data. So RESET may have the purpose of updating the memory registers. But if all TPMS are good/sending data then they are sending new data.
Do you never rotate tires? Without doing a reset, you end up with front tires that won't alarm until they drop below the rear pressure threshold (and rear tires that would alarm earlier, but who cares?). Until the next rotation, when they're back in the old places again.... -Chap
Only maybe for your Gen3 model year Chap, since my alarm values are permanently set. RESET has no value to me. Hitting RESET would be a good idea after tire work...that probably forces the system to get new data from the tires, to make sure the sensors are working. Otherwise you might not find out until a week later when your system finally realizes there is a non-working sensor. as I say, when a sensor dies, it takes my 2006 TPMS system a while (over a week) to say "hey wait a minute I got old data that is not getting updated"
I just now went to Toyota Techinfo (US site), opened the 2015 Owner's Manual. Here's snapshots from pages 448 and 449. It seems to say the tpms is resettable, and sets itself based on the tire pressures at time of reset.
Yes, all models of all years that I have seen have the reset button. Some owners never see it because it's down so low in a cramped location (under the dash by the steering column). Further, some of us have -two- of those buttons, one is for TPMS reset (labled), the other is for PCS on/off (also labled). Use a flashlight, lay on your back if you can on the drivers side floor and look up. You put the pressure in the tyres that you want to run at as per the manual posted above, cold please (not driven for at least an hour or two). Then you press the button and hold until the light blinks. Once you do this, when -any- tyre pressure except the spare (no TPMS on it) drops about 20% below that set value the light will come on. The Prius doesn't care where on the car the tyres are. It knows nothing about tyre rotation, nor does it care. Each pressure set point is based on the TPMS sensor serial number. When any sensor reports pressure drop 20% or more of the set value the light will be turned on. You may reset the alarm pressure as many times as you like. I have Pearl S set for 40 PSI front and 38 PSI rear, and while I adjust the pressure after a tyre rotation, I rarely reset the TPMS alarm points. It's only 2 PSI. Not worth bothering about. You can, with a little forethought and very little math, set the tyres such that they alarm at some pressure you might like, yet run at some other desired pressure not related to the alarm point. I leave this as an exercise for the reader.
I found the prior post where @NutzAboutBolts told me I think we all have RESET button from 2006 on, the question is what does it do? On a 2006 I do not think it adjusts the alarm value. You can see this value on Techstream, on a Gen2 anyways, so if you have your car hooked up to Techstream, you could hit reset and see what happens.
