Join Date: Dec 2010
Location: The Great Big Box
TPS (or TPMS) are a brilliant convenience for those who use their cars as drivers and don't want to have to worry about all of the safety checks that most don't have the time for. Believe it or not people do pay attention to that light when it comes on, and come to fill their tires up. It's on a very short list of government mandated safety devices that I actually advocate for.
Whoever said it works off of tire RPM is only partially correct. The direct system actually employs a pressure sensor inside of the tire that transmits a live feed to the vehicles computer, based off of the actual pressure inside of the tire.
An indirect pressure sensor uses RPM sensors to detect slight variances in angular velocity from an under-inflated tire, sensors not located inside of the tire. The vast majority of vehicles out there today employ a direct system, the indirect system is fading away.
If the light is still on there may be a few things at play:
1. Your tires are actually under-inflated.
2. Your pressure sensors are not set for the tires pressure (I.E. from bigger tires that run a lower pressure- it takes 3PSI difference to trip the sensor).
3. Faulty pressure sensing system, in which case the light would actually blink.
4. You need to manually reset the tire pressure light VIA button, normally located on the bottom of the dash panel.
All about that unibody life.