TPMS weird statement in Quick Start Manual
 

That makes no sense to me, unless it is saying that the tire pressure should be in the normal range before you press the TPMS "Set Switch". But the way it is worded seems to say that unless you change the pressure, the alarm will not work even if the pressure was correct when you used the "Set Switch."

It doesnt actually measure the tyre pressures, it just detects if 1 or more tyre drops below the pressure when the button is pressed to set a level.

Still don't understand...
 

I seem to remember that it does not actually detect pressure, it just looks for a difference in tire/tyre rotation that indicates low pressure. But the statement in the Quick Start Guide still makes no sense.

The TPMS does not detect the actual pressure. It detects the rotations of the tire through the ABS sensor. With this it can detect if one tire is rotating slower than the others, and it ass-u-mes that the tire that is spinning slower is low on air. Not the most reliable system to detect small air pressure changes, but if it is a big difference it will alert you. I suggest checking every week to every other week manually.