PATS Transceiver
WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
The PATS transceiver reads any key placed in the ignition lock cylinder. When the ignition changes to RUN or START, the BCM activates the PATS transceiver. Once the PATS transceiver activates, it activates the key in the ignition lock cylinder and receives the key data. Once the PATS transceiver receives the key data, it sends the data to the BCM.