419-01B Passive Anti-Theft System (PATS) - Vehicles Without: Keyless Entry and Push Button Start	2014 Fiesta
Description and Operation	Procedure revision date: 02/22/2013

Passive Anti-Theft System (PATS) - System Operation and Component Description

System Operation

System Diagram

Network Message Chart

IPC Network Input Messages

Broadcast Message	Originating Module	Message Purpose
PATS control command	PCM	The PCM sends the IPC a challenge request for a valid ID.

PCM Network Input Messages

Broadcast Message	Originating Module	Message Purpose
PATS start request target data	IPC	The response from the IPC supplying the PCM challenge ID. If the IPC ID response is incorrect, then PATS prevents the vehicle from starting.

PATS

The PATS is controlled by the IPC . There are two main checks the PATS performs before allowing the vehicle to start. If either of these checks fail, the PATS does not allow the vehicle to start and the anti-theft indicator in the IPC flashes rapidly.

These two checks are to verify that a programmed key is used to turn the ignition to ON or START and the IPC verifying the PCM ID to make sure it matches the PCM ID stored in memory.

The first check is initiated when the ignition switch is turned to the ON or START position. Once the IPC determines the ignition has been turned to ON or START, it generates a challenge message. It sends this challenge message to the PATS transceiver on the transmit circuit. The transceiver in turn reads the key and generates a response message that is sent back to the IPC on the receive circuit. The engine does not start if the message received from the transceiver does not match a key stored in the IPC memory.

Once the IPC determines a programmed key is used to turn the ignition to ON or START, the IPC sends the PCM a challenge message over the HS-CAN . When the PCM receives the challenge message, it generates a response and sends it back to the IPC . The engine does not start if the response from the PCM does not match the response in the IPC memory.

If both the PCM identification and key verification pass, the PATS allows the vehicle to start. The PATS cannot disable or stall a vehicle that has already been activated.

PATS Parameter Identifications (PIDs)

In conjunction with Diagnostic Trouble Codes (DTCs), the PATS Parameter Identifications (PIDs) are a useful tool when diagnosing PATS concerns.

IPC PID Chart

Acronym	Name	Description
M_KEYS_REQD	Minimum number of keys required	Minimum number of programmed keys required. This PID always reads 2.
KEYS_PROGMD	Number of keys stored	Number of keys currently programmed into the IPC .
PATSENABL	Vehicle Enable Status	Indicates if PATS allows the engine to start.
PCM_ID	PCM ID Status Stored	Indicates if there is a PCM ID currently stored into the IPC .
PCM_VFY	PCM Verify OK	Indicates if the PCM ID received by the IPC matches the PCM ID stored in the IPC memory.

Component Description

Integrated Keyhead Transmitter (IKT)

The vehicle comes equipped from the factory with two programmed Integrated Keyhead Transmitters (IKTs). The Integrated Keyhead Transmitter (IKT) incorporates both the PATS and the RKE transmitter functions in a single device. The key programming is a two step procedure. The PATS information is programmed into the IPC and then the RKE transmitter is programmed into the BCM . The IPC accepts the programming of an unlimited number of keys, and the BCM accepts the programming of up to 8 keys

PATS Transceiver

The PATS transceiver reads any key placed in the ignition lock cylinder. When the ignition changes to ON or START, the IPC activates the PATS transceiver. Once the PATS transceiver activates, it activates the key in the ignition and receives the key data. Once the PATS transceiver receives the key data, it sends the data to the IPC .

IPC

When the IPC is replaced, it is necessary to program at least 2 keys and perform the parameter reset procedure.

The IPC requires PMI when replaced.

BCM

When the BCM is replaced, it is necessary to program the RKE transmitter of each key to the BCM .
Refer to: Remote Keyless Entry (RKE) Transmitter Programming (501-14 Handles, Locks, Latches and Entry Systems, General Procedures).

The BCM requires PMI when replaced.