Anti-theft system — passive (Defender 2007+)

Location of elements

Pos.	spare part no	Name
1	-	Dashboard
2	-	engine control module (ECM)
3	-	Starter relay
4	-	Glow plug relay
5	-	Transceiver winding
6	-	Anti-theft module

Review

The 10AS anti-theft system, together with the ECM, controls the operation of the passive anti-theft system. The passive anti-theft system immobilizes the engine by disabling the starter relay and fuel injectors until the correct RFID remote control code is received.

The passive anti-theft system provides 2 levels of protection:

• Engine block only
• Blocking of the engine plus inclusion of protection of perimeter and volume.

For more information, see the chapter: Anti-theft system - active (419-01A Anti-theft system - active, Description and principle of operation).

The anti-theft system module activates the immobilizer 30 seconds after the key is removed from the ignition and the driver's door is opened. If the key is removed from the ignition but the driver's door is closed, the anti-theft system module will activate the immobilizer after 5 minutes.

Transceiver winding

The winding of the transceiver is a coil on the ignition lock cylinder. When the ignition switch is turned to position II, the anti-theft system module supplies DC voltage from the battery and AC voltage to the transceiver coil. This creates a magnetic field around the ignition lock cylinder, which disappears and reappears in accordance with the ripple of power supplied from the anti-theft system module. The pulsation of the magnetic field activates the remote control, which transmits a turn-on signal.

Anti-theft module

The anti-theft system module is located behind the instrument panel; together with the ECM, it controls the operation of the passive anti-theft system. The anti-theft system module receives constant voltage from the battery through the battery electrical junction box (BJB) and ignition voltage through the central fuse box (CJB).

For more information, see the chapter: Battery and wires (414-01 Battery, battery mount and wires, Description and principle of operation).

The activation code is transmitted to the anti-theft system module from the remote control. The activation code is received by the anti-theft module's antenna, which is located vertically below the module. The anti-theft system module determines the authenticity of the code coming from the remote control by comparing it with a sample in the device's memory.

The anti-theft module also controls the following functions:

• active anti-theft system. For more information, see the chapter: Anti-theft system - active (419-01A Anti-theft system - active, Description and principle of operation).
• central locking. For more information, see the chapter: Handles, locks, latches and entry systems (501-14 Handles, locks, latches and entry systems, Description and function).
• interior lighting. For more information, see chapter: Interior lighting (417-02 Interior lighting, Description and principle of operation).
• light alarm. For more information, see the chapter: Outdoor Lighting (417-01 Outdoor lighting, Description and principle of operation).

The engine control unit

The ECM is mounted on the bulkhead of the engine compartment; together with the anti-theft module, it controls the operation of the passive anti-theft system.


For more information, see the chapter: Electronic controls (303-14 Electronic Controls - Diesel Engine ID4 2.4L, Description and Operation).

Control scheme

NOTE: A = rigid connection; D = high speed bus CAN communication protocol (CAN)

Pos.	spare part no	Name
1	-	Battery
2	-	Transceiver winding
3	-	Anti-theft module
4	-	Diagnostic connector
5	-	Dashboard
6	-	ECM
7	-	CJB
8	-	Starter relay
9	-	ignition switch
10	-	BJB
11	-	Glow plug relay

Work principles

The anti-theft system module receives continuous power from the battery via fuse 7 in the BJB. When the key is inserted into the ignition switch and turned to position II (ignition on), the anti-theft system module is also powered by fuse 8 CJB.

Powered by the ignition coil, the anti-theft system module activates the transceiver coil by applying battery voltage from terminal 12 of connector C0057 and AC voltage from terminal 7 of connector C0057.

The alternating voltage supplied by the anti-theft system module causes the magnetic field created and lost by the transceiver winding. The pulsating magnetic field activates the remote control, which transmits the activation code to the anti-theft system module.

The anti-theft system module receives the activation code on its antenna. This code is compared with the value stored in memory. If the code matches, the anti-theft system module sends an enable signal to the instrument panel. The instrument cluster acts as a gateway, converting the signal transmitted by the anti-theft system module into a signal available for processing by the ECM. This signal is then transmitted by the instrument panel to the eCm, which energizes the starter relay and fuel injectors, allowing the engine to start.

Emergency access with a key

If the immobilizer is on and there is no remote control, the engine can be started by performing the emergency key entry procedure. For emergency key access, see the User's Guide.