Discovery 2. Manual - part 328

ALARM SYSTEM AND HORN

DESCRIPTION AND OPERATION 86-4-17

Operation

Standard system functions
All vehicles have the following functions as standard.

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Locking.

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Unlocking.

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Fuel cut off switch unlocking.

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Internal locking.

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Electric fuel flap release.

Locking
The doors are locked by pressing the lock button on the handset or by locking the vehicle from the driver's door with 
the key.

In order to lock the vehicle, the following conditions must be met:

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The driver's door is closed.

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The ignition is off.

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The fuel cut off switch is not tripped.

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The bonnet is closed.

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The vehicle is not super locked.

Depending on system configuration a mislock occurs if these conditions are not met. The doors may lock (depending 
on condition not met) and the system may not fully arm, depending on configuration of the system. If a mislock occurs 
an audible warning is emitted and the vehicle becomes partially armed.

Unlocking
The doors are unlocked by pressing the unlock button on the handset or by unlocking the vehicle from the driver's 
door with the key. This may unlock only the driver's door or it may unlock all doors depending on system configuration.

Fuel cut off switch unlocking

In the event that the vehicle experiences a force strong enough to actuate the switch, all the doors on the vehicle 
immediately unlock.  The following conditions must be met for this to occur:

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The security system is not armed.

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The ignition is on.

This same action causes the fuel pump to shut off and disables the Engine Control Module (ECM). In some markets, 
this action may also cause the direction indicators lights to flash.

ALARM SYSTEM AND HORN

86-4-18 DESCRIPTION AND OPERATION

Internal locking
Internal locking allows the doors to be locked / unlocked from a central position using switches on the instrument 
panel.  The internal unlock switch will not operate if the vehicle is super locked.

Electric fuel flap release

Up to 03 model year shown

The fuel flap is opened by pressing the button on the fascia on vehicles up to 03 model year or on the instrument pack 
binacle on vehicles from 03 model year.  This works only if the anti-theft system is not armed and the ignition is off.  
In some configurations, it may also be necessary to remove the key from the ignition switch.

Configurable system functions
The following alarm system features are configurable using TestBook.

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Perimetric alarm.

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Volumetric alarm.

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Super locking.

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Partial arming.

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Mislock.

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Passive immobilisation.

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Passive remobilisation.

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Emergency key access.

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Single point entry.

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Speed related locking.

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Acclimatisation related locking.

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Visual warnings.

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Audible warning.

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Theft deterrent led.

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Transit mode.

Perimetric alarm
The perimetric alarm is used by the BCU to detect unauthorised opening of a door or hinged panel. Switches 
incorporated into the door latch assemblies and the bonnet determine the state of the panels.

There are two perimetric alarm configurations:

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Alarm not active.

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Alarm active.

Arming: To arm the perimetric alarm, press the lock button on the handset or lock the vehicle using the key in the 
driver's door. Once the alarm has been set, the BCU monitors the state of the doors and the bonnet.

In order to arm the perimetric alarm the following conditions must be met:

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Drivers door closed.

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Key not inserted in ignition switch.

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Fuel cut-off switch not tripped.

ALARM SYSTEM AND HORN

DESCRIPTION AND OPERATION 86-4-19

Disarming: To prevent the alarm from triggering when entering the vehicle, the alarm system must be disarmed with 
the key or the handset.

There are two perimetric alarm disarming configurations:

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Always disarm with key.

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Only disarm with key if locked with key.

The perimetric alarm can be disarmed by unlocking the vehicle with the handset or by using the key in the driver's 
door lock, depending on system configuration.

NOTE: The “only disarm with key if locked with key” configuration prevents the alarm from being disarmed by 
unlocking the vehicle with the handset if the vehicle has been locked by the key. In this situation the Emergency Key 
Access (EKA) code must be entered to disarm the alarm.

In order for the alarm to trigger, the following conditions must be met:

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Perimetric alarm armed.

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Bonnet or door opened.

Once triggered, the alarm will remain triggered for 30 seconds before resetting.

Volumetric alarm
The volumetric alarm is used by the BCU to detect movement within the vehicle. This allows the alarm to be triggered 
if a window is smashed in an attempt to gain access to the vehicle.

There are two volumetric alarm configurations:

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Volumetric alarm not active.

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Volumetric alarm active.

Two sensors, which transmit and receive ultrasonic signals, detect movement within the vehicle. Theses sensors 
detect any change in air movement within the vehicle and then supply the BCU a signal to activate the alarm. Fifteen 
seconds after the vehicle is locked with the handset or the key the volumetric alarm is armed. This delay is 
incorporated into the BCU software to prevent accidental or nuisance triggering of the alarm.

In order to arm the volumetric alarm, the following conditions must be met:

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Driver's door closed.

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Key not inserted in ignition.

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Fuel cut-off switch not tripped.

To prevent the alarm from triggering when entering the vehicle, the alarm system must be disarmed with the key or 
the handset.

There are two volumetric alarm disarming configurations:

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Always disarm with key.

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Only disarm with key if locked with key.

The volumetric alarm can be disarmed by unlocking the driver's door with the key or the handset, depending on 
system configuration.

NOTE: The “only disarm with key if locked with key” configuration prevents the alarm from being disarmed by 
unlocking the vehicle with the handset if the vehicle has been locked by the key. In this situation the EKA code must 
be entered to disarm the alarm.

In order for the alarm to trigger, the following conditions must be met:

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Volumetric alarm armed.

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Volumetric sensors triggered.

Once triggered, the alarm will remain triggered for 30 seconds before resetting.

ALARM SYSTEM AND HORN

86-4-20 DESCRIPTION AND OPERATION

Super locking
Super locking prevents the use of the interior door handles to unlock and open the vehicle doors. This prevents the 
doors from being opened if the window be smashed in an attempt to gain access to the vehicle.

There are four configurations for super locking:

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No super locking.

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Super locking on single handset press only (no key activated super locking).

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Super locking on single handset press or single key turn.

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Super locking on double handset press or double key turn.

To super lock, press the lock button on the handset once or twice within one second depending on system 
configuration.  In some configurations, it is also possible to super lock the vehicle using the key in the driver's door.  
This also may require one or two turns of the key in the lock direction.  If two turns of the key are required to activate 
super locking, the two turns must occur within one second of each other.

In order to super lock the vehicle, the following conditions must be met:

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All door are closed.

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The ignition is off.

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The fuel cut-off switch is not tripped. 

Partial arming
Partial arming allows protection of as much of the vehicle as possible if the alarm is armed with one or more doors or 
the bonnet open.

Partial arming allows the vehicle alarm to be armed even if the following conditions exist. When the bonnet or door is 
closed, the BCU activates the perimetric alarm and the volumetric alarm after 15 seconds have elapsed:

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The bonnet is not closed: If the bonnet is open when the alarm is armed, the BCU activates super locking and 
volumetric sensing. In this condition, the alarm enters a partially armed state. All other functions of the alarm are 
active and the BCU monitors the bonnet for a change of state. If the bonnet closes, the system is completely 
armed.

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The passenger door, a rear door or the tail door is not closed: If a door is open when the alarm is armed, the BCU 
does not activate super locking or volumetric sensing. In this condition the alarm enters a partially armed state. 
All other alarm functions are armed and the BCU monitors the open door. If the door closes volumetric sensing 
and super locking become active.

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Failure of a door latch switch: If a short circuit in the door latch switch occurs, the BCU presumes the door is not 
closed. In this situation the BCU does not activate super locking or volumetric sensing. All other alarm functions 
are armed.

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Damaged wiring harness: If a short circuit in the wiring harness for the door latch switch occurs, the BCU 
presumes the door is not closed and does not activate super locking or volumetric sensing; all other alarm 
functions are armed. If an open circuit in the wiring harness for the door latch switch occurs, the BCU presumes 
the door is closed and arms the alarm as normal.

Mislock
Mislock alerts the driver that a failed attempt has been made to lock the vehicle because of the doors or the bonnet 
not being fully closed.

There are six audible configurations for mislock:

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No audible warning.

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Alarm sounder.

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Vehicle horn.

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Alarm sounder and vehicle horn.

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BBUS.

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Alarm sounder, vehicle horn and BBUS.

When a failed attempt has been made to lock the vehicle, the audible warning device is switched on for 50 ms and 
off for 200 ms. The BCU allows the audible warning device to operate 3 times.