Passive Anti-Theft System (PATS) Function

WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

The PATS function is controlled by the IC . The PATS uses the IC to carry out all of the PATS functions such as receiving the identification code from the PATS key, issuing a signal to the PCM to control the starter and fuel injectors enable, and initiating the key interrogation sequence when the ignition key is turned to the ON or START position. Because of the interaction between the IC and the PCM, there are parameters that must be set if the IC or the PCM (or both) are replaced. Refer to PASSIVE ANTI-THEFT SYSTEM (PATS) PARAMETER RESET . If the IC must be replaced for any reason (PATS concerns or an IC concern), the PATS keys also must be programmed into the new IC . Refer to INTEGRATED KEYHEAD TRANSMITTER (IKT) KEY PROGRAMMING USING DIAGNOSTIC EQUIPMENT . All elements of PATS must be functional before the vehicle starts. If any of the components are not working correctly, the vehicle does not start.

PATS is active only for a few seconds when the vehicle is starting. It is not a PATS concern if the vehicle stalls after it has been running for a minimum of 3 seconds. PATS does not disable a running vehicle.

PATS can cause a vehicle no start due to either the fuel injectors or the starter not operating (starter relay does not close) or both. Always check for PATS DTCs from the IC and DTCs from the PCM when a no-crank or no-start condition exists. A low state of charge in the vehicle battery can cause the PATS to allow starter operation, but prevent the fuel injectors from operating.

If the anti-theft indicator does not prove out (it may be either flashing or glowing steadily) and one (or both) of the previous conditions (fuel injectors and/or starter inoperative) are present, it may be due to a PATS issue. If the anti-theft indicator proves out, it may not be a PATS issue. If the anti-theft indicator does not illuminate at all, it may be an IC issue. GO to SYMPTOM CHART .

PATS disables the vehicle from starting if there is:

a damaged PATS key.
an unprogrammed PATS key.
a non-encoded key (a conventional key or one that does not have any electronics).
damaged wiring.
a damaged transceiver.
a damaged IC .
a damaged PCM.

PATS is not compatible with aftermarket remote start systems, which allow the vehicle to be started from the exterior of the vehicle. These systems can reduce the security of the vehicle, and can also cause no-start concerns. Remote start systems must be removed from the vehicle before any PATS -related no-start concerns are investigated.