Range Rover P38
86
ELECTRICAL
NEW RANGE ROVER
12
DESCRIPTION AND OPERATION
Ultrasonic Sensor
The ultrasonic sensor is located adjacent to the left
hand ’B/C’ post on the interior headlining and is used
to detect movement within the vehicle when the
volumetric function of the alarm system is active.
Self check
Each time the ignition is switched off, the BeCM
initiates the ultrasonic sensor to perform a self check
procedure to ensure correct operation. When the
ignition is switched off the sensor is activated for a
period of 60 seconds or until the driver’s door has
been opened and closed or the vehicle has been
locked using the key or the remote handset.
During the self check, the sensor expects to detect the
driver leaving the vehicle. If the sensor detects no
movement but a driver’s door open and close
sequence has occurred, the BeCM logs this as a
sensor failure. If five consecutive failures are logged,
the BeCM will log a sensor failure and ’ALARM
FAULT’ will be displayed on the message centre when
an attempt to superlock the vehicle is made or the
ignition key is inserted in the ignition switch.
When a valid self check sequence occurs, the BeCM
will set the log counter back to zero. If no movement is
detected during a self check and a driver’s door open
and close sequence has not occurred, the BeCM will
not count this as a failure or a valid self check.
Nuisance triggering
When a valid superlock request is received and all
windows are closed and set, the BeCM will wait 5
seconds before activating the ultrasonic sensor to
allow the air in the vehicle to settle. After the 5 second
period, the BeCM monitors, via the sensor, for
movement within the vehicle.
If movement is detected in this 10 second period the
alarm will be triggered and superlocking will be
prevented. If no movement is detected, the vehicle will
superlock and volumetric sensing will be active to
monitor the vehicle interior.
Perimetric Alarm
The doors, tail door and bonnet are all monitored by
the BeCM. Microswitches within the door latch
mechanisms, and a plunger type switch for the
bonnet, signal the BeCM if the panel is opened. If the
alarm is armed, the BeCM will trigger the alarm
sounder and visual indications if a panel is opened.
Immobilisation
Refer to ’Engine Management’ earlier in this
description and operation for immobilisation
information.
Passive immobilisation
On petrol and Diesel vehicles from 96MY, a market
programmable passive immobilisation feature was
introduced. The feature automatically immobilises the
vehicle when the ignition is turned off even if the
vehicle is not locked.
When the key is removed from the ignition and the
driver’s door opened, the BeCM will immobilise the
engine after a 30 second period. If the ignition is
turned off or the key is removed from the ignition and
the driver’s door is not opened, the BeCM will
immobilise the ignition after a 10 minute period.
Unlocking the vehicle with the remote handset or
using the EKA procedure, if the key is not inserted in
the ignition within 30 seconds, the BeCM will change
to the immobilised condition. Inserting the key in the
ignition causes the passive coil around the ignition
switch to be energised. The passive coil remains
energised until a valid code from the remote handset
is received or the BeCM goes into sleep mode.
Remote handset
The remote handset locking signals are encoded via a
rolling code algorithm. The BeCM has a capture range
of 100 codes after the previously received value. The
remote handset can be operated up to 100 times, out
of range of the vehicle before synchronisation with the
BeCM is lost. The code sequence is stored in the
BeCM RAM and resynchronisation will be required if
the battery is disconnected for a length of time.