When Monitored:
WARNING: This page is about a different car, the 2012 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.
At ignition on the Occupant Classification Module (OCM) supplies 5 volts to power up the Left Front Passenger Seat Weight Sensor. Every time the sensor is powered up it sends an initialization message containing the sensor serial number to the OCM.