Passive Anti-Theft System (PATS) Operation

WARNING: This page is about a different car, the 2011 Mercury Milan, 2011 Lincoln MKZ, and 2011 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

The PATS function is controlled by the IPC. With this type of PATS, there are parameters that need to be reset if either the IPC and/or the TCM are replaced. Refer to PASSIVE ANTI-THEFT SYSTEM (PATS) PARAMETER RESET in this service information. When the PATS key is turned to the ON or START position, the IPC initiates the key interrogation sequence by sending a voltage signal to the PATS transceiver. The transceiver then uses its antenna to bounce a signal off the transponder in the PATS key. This process "reads" the PATS key ID code and sends the key ID code back to the IPC, which interprets it and determines if it matches one of the stored key codes. If it does match one of the stored key codes, the IPC sends a message to the TCM to enable the engine and the electric drive. If it does not match one of the stored key codes, or it is only a partial key read or no key read, the IPC sends a message to the TCM to not enable the engine and the electric drive. The anti-theft indicator in the IPC flashes (or glows steadily) and the IPC stores one or more DTCs. All elements of PATS must be functional before the vehicle starts. If any of the components are not working correctly, the vehicle cannot start. If the IPC must be replaced for any reason, the PATS keys must also be programmed into the new IPC. Refer to INTEGRATED KEYHEAD TRANSMITTER (IKT) KEY PROGRAMMING USING DIAGNOSTIC EQUIPMENT in this service information.

PATS disables the vehicle from starting if there is:

a damaged PATS key.
a non-programmed PATS key.
a non-PATS key (key has no electronics).
less than 2 keys programmed.
damaged wiring.
a damaged transceiver.
a damaged IPC.
a damaged TCM.