Principles Of Operation - PATS
WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. However, it is still accessible from the selected car via links, so may be relevant.
The passive anti-theft system (PATS) is initiated by turning the key to the ON or START position. When a valid PATS key is turned to the ON or Run position the PCM queries the PATS transceiver over circuit 1215 (WH/LG). The transceiver then reads the key code and sends the code to the PCM over circuit 1216 (OG/LB). The PCM then validates the read code against stored authorized keys. If the codes match the PCM then enables the starter using circuit 1419 (LG/YE). If the codes do not match the starter will remain disabled and the vehicle will not start. The PCM will then flash or turn on the anti-theft warning indicator light to indicate the fault.