Un4Scene

Wow... that sounds like a truly useless system. Consider - every time you go through a curve your wheels are spinning at different speeds. Whenever you get a little bit of wheel spin on a slick road, there's a side-to-side difference in wheel speed (since the tC doesn't come stock with an LSD).

That means that it would have to measure a consistent change in average wheel speed over a certain length of time. That, in turn, means that you could be driving with a flat tire for an hour before the TPMS light comes on. There's also the issue of the amount of pressure it would take to actually change the overall diameter. I add about 10PSI to my tires for road trips (adds about 2 mpg), and then set it back to normal for normal driving. I've never reset the TPMS, and I've never seen the light come on. Who came up with this brilliant design?

Anyways...
I'm assuming it measures the speed of each wheel independently from the other wheels? Otherwise you'd have a TPMS light if you replaced one tire and not the others.

So the light could be coming on due to a problem with the ABS system. If a sensor was bad or a wire was broken, then it should trigger the ABS light. Could it be something wrong with the ABS rotor - a broken tooth or something? Maybe a bad CV boot causing isuues with grease and what-not? Maybe a sensor that's gone bad in a way that the system isn't recognizing it as bad? I don't know, I'm just spit-balling here.

Syldrin

iTrader: (1)

that is why they don't use it anymore. it isnt the best system. on a side note. i was driving to work today and the light.... went off! i don't know what happened but i'm not going to complain.

SquallLHeart

The old TMPS system did account for turns and whatever wheel spin you got.

However, yes, it does require a certain amount of time for differences to be seen. It's primarily used in cases to detect a SLOW leak in a tire. So yes, if the tire blows out, the TPMS isn't going to see it.
(i doubt it'll take more than a few minutes though, and by then you should already know your tire is blown with the instability)

The old TPMS also only compared the current status of the tires TO ONE ANOTHER... so if you decide to add 10psi to all the tires... then the TPMS will be ok with it... it doesn't see a big change between the tires to one another... because there isn't one.

if you add say, 10psi to only 3 tires... then.. sure! the TPMS will be like, "WTF?!" and then turn on the warning light because of the small difference in the 4th tire.

and YES! if you replaced one tire, the TPMS will complain when it sees the difference.. thus you need to check the tire pressures, and re-initialize the system if necessary.

it's also noted in the owner's manual that the light might turn on and you may need to re-initialize if you replace or rotate tires.