Location 3rd gen tire pressure switch

What exactly are you looking for? The TPMS sensors are part of the valve stems. To set the system you inflate the tires to the proper pressure and press and hold the switch under the steering wheel for three seconds (it will blink and beep, I think). You must have the car in ignition on for at least five minutes after you do this for it to fully activate.

To see the TPMS set switch you just about have to put your head on the floor (drivers side).

 

Adding to the location instructions above, it's almost directly next to (to the right) the OBD port. It's a small button with the TPMS icon above it. If I recall, you put the car in IG-ON (press POWER twice w/o pushing the brake pedal down), then press & hold the TPMS button and I believe the light will flash 3 times. Then you're all set.