Anti-theft system: Immobilization

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Land Rover Discovery, 2003 Land Rover Discovery, 2002 Land Rover Discovery, 2001 Land Rover Discovery, and 2000 Land Rover Discovery. However, it is still accessible from the selected car via links, so may be relevant.

For immobilization, the BCU disables the starter motor relay. When the engine is cranking, the ECM looks for a coded signal from the BCU. If the signal is not received within one second of cranking, the fuel supply to the engine is stopped and the injectors are disabled. This also prevents unburnt fuel from entering the catalyst.

If the BCU is disconnected, the engine starter motor will remain isolated by the starter motor relay and the ECM will remain immobilized. The main wiring for the system is contained within the main harness which is relatively inaccessible, so preventing intruders from disabling the system by cutting the wires for the immobilization system. Once the immobilizer has been activated, destruction of the trigger device or the wiring to it will not disarm the system.

The RF transmitter communicates to the BCU via the RF receiver using a 70 bit code. Pressing the unlock button on the transmitter will re-mobilize the vehicle. The RF transponder is integrated into the metal key assembly, inserting the key into the ignition switch will induce a signal in the exciter coil to re-mobilize the vehicle.