push the button to set the tyre pressure if you have a new tyre put on or whatever. This set's a record of what the rolling radius should be. If you get a flat then in theory the rolling radius of the tyre will be less so the ABS sensor should notice and flash the light up on the dash..
That is how it is
supposed to work . . . . .
doesn't often work though by the sounds of it!
. . . . correct. Its useless.
Just to give a few indications of crap it is (and just to clarify, I allways press the tit everytime I need to adjust my pressures, so about every other month):
Recently changed some very worn 225 boots on the front with some brand new 235s - so a notable change in radius - and not a whimper of a warning. Swapped fronts to rears - again no warning!
A while earlier, I had some Monza IIs replaced under warranty, and on the drive home, noticed the rear end very unstable, got home and noticed the rear tyres were clearly underinflated. Next morning checked the pressures - to my utter disgust, the stealer had ONLY put 22 psi in one rear and 18 psi on the other - so a serious pressure 'loss' - yet the TPMS failed to warn!
To say the DP got a gobfull (for his utterly incompetent 'mechanics') was an understatement!
