Theory Of Operation
WARNING: This page is about a different car, the 2009 Jeep Grand Cherokee. However, it is still accessible from the selected car via links, so may be relevant.
The TPM Transponder, also known as a Tire Pressure Trigger Module, is used to automatically learn the location of each wheel sensor on the vehicle. The module is controlled and activated in sequence by the Wireless Ignition Node (WIN) over a LIN bus. When activated, the module will generate a 125 KHz signal of sufficient field strength to trigger the tire pressure sensor and force a RF transmission from the sensor.