TPMS question

[wparente]

So the first cold day we have I get a warning that the right front wheel is low on pressure. I turn the car off, get out and check it and everything seems to be OK. I had a tire gauge with and yes it had dipped to 32psi or so, but still safe to get home. I start the car up and low and behold the car shows all four corners low. Thinking I may have ran over a bunch of debris I get out and check everything thing and find all tires at 30 plus psi so no panic. When I get home I air up to 36 and 39 psi (17in) and everything resets as you would expect.
So here is my question, other than to say it just coincidence, has this happened to anyone else where it goes from one tire to all four and if so has it happened more than once? By shutting off the engine did it rescan and get confused? Second this being my first encounter with the TPMS system does it distinguish between low psi say 32psi and no psi (as in flat)? The manual talks about red and yellow but doesn’t really distinguish much between the two. I assume red is 0psi. And lastly does TPMS monitor pressure at all or is it strictly rotational based? If it’s just rotational based, why not just use part of the ABS to check wheel rotation speed?

 

[TitanTim]

I'm pretty sure the sensors work off the ABS so if you get a puncture on the move the affected wheel rotates at a different rate to the others and sets the monitor off. I thought it would only go off with a pressure loss of 20% or more so wouldn't have thought it would go off with just a few PSI drop in pressure.

Mine was playing silly beggars a month or two back after each time I washed the car. I would pull it out onto the drive and everything fine. Washed the Zed and as soon as I put the fob in the ignition I would get a warning triangle with an exclamation mark inside light on the dash, then when the car started the low tyre pressure bong would sound with the dash symbol, I think it was yellow, but as you say the handbook isn't exactly helpful. I checked tyre pressures and all fine so reset the monitor. All was fine until the next couple of washes and it did exactly the same but no pressure loss. Was going to book into the dealers then it suddenly stopped doing it and has been fine since. I can only thing the computer threw a wobbly and then righted itself. When I come to think of it I did use around the time it started a wheel sealant spray and remember spraying it on the calipers and I wonder if it upset the sensors somehow.

Tim.

 

[Wondermike]

The system uses the ABS sensors in the UK but in the US it uses proper sensors.

 

[Anonymous]

Mine has been going off for a couple months and can't figure it out. I replaced the rear sensors and no luck. Next step is to replace the front and see if that does the trick.