patperry2766 wrote:
While I'm not 100% sure, if memory serves, the indicators are activated by the different rotational speeds of the tires based on the diameter of the tires based upon their inflation levels. A under inflated tire will rotate with a different RPM that a properly inflated tire.
There are two different types of TPMS warning systems. Look at about 3:20 of the video and this will explain why the warning indicator wasnt tripped when all 4 tires are inflated/deflated to equal PSI.
http://www.tpmsmadesimple.com/how_tpms_works.php
