L322 Range Rover System Description and Operation
SECURITY
DESCRIPTION AND OPERATION 86-5-21
Repetition Blocking
To protect the door latch actuators the BCU incorporates a repetition blocking feature. The BCU increments an
internal counter by one each time an actuation occurs and decrements the counter by one every 8 seconds. If the
counter exceeds 15, the BCU blocks further unlocking commands until the counter returns to 15 or less. The block is
ignored if the BCU receives a crash signal or the system goes from superlocked to locked. In addition to the counter
for the side doors, separate counters are maintained for each of the tail doors.
Lockout Protection
The vehicle cannot be locked when either of the front doors is open. The vehicle cannot be superlocked when the
driver's door is open.
Alarm System
The alarm system arms and disarms in conjunction with the superlocking and unlocking of the locking system.
Depending on the configuration of the BCU, the alarm system can be armed and disarmed when the locking system
is activated with the driver's door lock or the remote handset, or only with the remote handset. Visual and audible
confirmation of the alarm system arming and disarming, using the direction indicators and the BBUS, are also
configurable in the BCU.
When the vehicle is superlocked, the BCU sends an arming signal to the tilt sensor, which relays it to the BBUS and
the volumetric sensor. If the BCU does not receive an acknowledgement signal from the tilt sensor and the volumetric
sensor within 1 second, the BCU disables the associated alarm feature for the remainder of the armed cycle.
If the BCU detects two superlocking signals within 10 seconds, it disables volumetric sensing and tilt sensing. This
feature prevents accidental triggering of the alarm system during transportation of the vehicle or if a pet is left in the
vehicle.
Perimetric Sensing
When the alarm system arms, the BCU waits for 3 seconds before it begins monitoring the door status switches and
the bonnet switch for perimetric sensing. If a door or the bonnet have been left open, the BCU indicates this by flashing
the alarm LED for approximately 10 seconds. The input from the open switch is ignored until 3 seconds after it
changes to the closed state.
Volumetric Sensing
The BCU begins volumetric sensing 30 seconds after receipt of the superlock signal, the last door closes or
convenience closing stops, whichever occurs last.
If the alarm has been triggered, the BCU will ignore further volumetric sensor signals for the duration of the alarm.
The BCU resumes volumetric sensing 30 seconds after the alarm has stopped sounding.
Volumetric sensing and tilt sensing are disabled if the BCU receives a tail door open signal from the remote handset.
The BCU resumes volumetric sensing and tilt sensing 30 seconds after the upper tail door closes again.
Emergency Disarming
If the alarm has been triggered and cannot be disarmed with the driver's door lock or the remote handset, it can be
disarmed with the ignition switch as follows:
1 Use the ignition key to unlock the driver's door.
2 Sit in the vehicle and ensure all the doors are closed.
3 While the BBUS is still sounding, put the ignition key in the ignition switch and turn it to position I. The alarm LED
stays on instead of flashing.
4 After 10 minutes, the BBUS stops sounding, the alarm LED goes off, the locking system unlocks and the
immobiliser is made inactive.
Emergency disarming is configurable in the BCU.
