Central door locking (Body control unit)

Passive coil The passive coil is located around the ignition key barrel. When the BCU detects that the ignition key has been turned to the crank position, the vehicle's immobilisation system is activated and a signal is sent to the passive coil at a frequency of 125 kHz. The magnetic field generated in the coil is induced in the remote transmitter to trigger a remobilisation signal.

BBUS/ alarm sounder/ vehicle horn The BBUS is an audible warning device which operates under the control of the BCU if the anti-theft system is activated or the vehicle battery is disconnected. The unit contains its own internal battery power source which is charged via a feed from the passenger compartment fuse box. The BBUS will not sound if the battery is disconnected while the security system has not been set.

Some markets utilise an alarm sounder which operates independently or in conjunction with the vehicle horn if the anti-theft system is triggered.

Security system status LED The LED flashes when the anti-theft system has been set. There are four different flash rates dependent on mode of operation or other system information.

Central door locking

The doors can be locked by the following methods: l Pressing the lock button on the remote transmitter. l Locking the vehicle from the driver's door with the key. l Pressing the lower half of the central door lock switch. l Pushing the sill button down (will only lock that particular door). l By driving over 7 km/h (4 mph) – ( if the speed related locking function has been enabled).

The BCU will prevent locking if the logical conditions for locking are not satisfied. Conditions which will prevent door locking include: l Driver's door open. l Ignition switch on. l Inertia switch tripped. l Vehicle is already superlocked.

A mislock may occur if the logical conditions are not met.

The doors can be unlocked by the following methods: l Pressing the unlock button on the remote transmitter l Unlocking the vehicle from the driver's door with the key. l Pressing the upper half of the central door locking switch (not operational if the vehicle is superlocked). l Pulling the interior door handles (not operational if the vehicle is superlocked). l Inertia switch being triggered while the ignition is on and the security system is de-activated.

The BCU supplies information via the serial data bus to the IDM to energise the coil of the relays for each of the door lock actuators.

The BCU normally checks the following inputs to determine lock/ unlock requirements: l Unlock request. l Lock request. l Superlock request. l Single point entry request. l Lock passenger and rear doors request.