Anti-Theft - Passive: Introduction

The passive anti-theft system (PATS) prevents the vehicle from being driven away by unauthorized persons. This is achieved by having uniquely coded keys (both passive and transponder) and an encoded data exchange between multiple control modules. Unauthorized starting is prevented by inhibiting the engine crank, fuel and ignition systems.

The passive anti-theft system (PATS) is a function of the passive start system. The system uses the following components:

• Smart key(s)
• Three LF antennae
• A RF receiver
• A keyless vehicle module
• A start control module
• The central junction box (CJB)
• The engine control module (ECM)
• The instrument cluster.

The system is automatic and requires no input from the driver. The engine starting process is initiated when the start/stop switch and the brake pedal are pressed simultaneously. The engine management system will only allow the engine crank, fuel and ignition functions when the following conditions are met:

• A hardwired P (park)/N (neutral) signal is received from the transmission control module (TCM)
• A hardwired ignition signal is received from the central junction box (CJB)
• A hardwired crank request signal is received from the central junction box (CJB)
• An encrypted data exchange between the instrument cluster and the engine control module (ECM) is verified.

Before the central junction box (CJB) will send the hardwired ignition signal, it must satisfactorily complete the following:

• Exchange encrypted data with the keyless vehicle module to validate the smart key
• Exchange encrypted data with the instrument cluster to authorize the ignition status.

Additionally, before the central junction box (CJB) will send the hardwired crank request signal it must receive the following signals:

• Brake pressure signal from the anti-lock brake system (ABS) module, which must be greater than a pre-determined threshold
• Hardwired transmission in P signal from the JaguarDrive selector.