L322 Range Rover System Description and Operation
SECURITY
86-5-10 DESCRIPTION AND OPERATION
BBUS Harness Connector
BBUS Harness Connector C0666 Pin Details
Volumetric Sensor
The volumetric sensor is installed behind openings in the rear interior lamp and monitors for intrusion into the
passenger compartment when the alarm is armed.
The volumetric sensor consists of a microcontroller, two acoustic transmitters and two acoustic receivers. One
transmitter/receiver pair faces forwards and one transmitter/receiver pair faces rearwards to ensure complete
coverage of the passenger compartment. The front transmitter/receiver pair are in a rubber mounting attached to the
microcontroller housing. The rear transmitter/receiver pair are in a remote rubber mounting and connected to the
microcontroller housing by a four wire lead.
The volumetric sensor is powered by a permanent battery feed from the passenger compartment fusebox. The BCU
activates and de-activates the volumetric sensor when it arms and disarms the alarm system. When the volumetric
sensor is active it outputs ultrasonic pulses from the transmitters and checks the echoes picked up by the receivers
for changes to the passenger compartment profile. If it detects a change of profile indicating movement in the
passenger compartment the volumetric sensor reports the alarm to the BCU.
Each time the volumetric sensor is activated it performs a self test. If there are no faults the volumetric sensor sends
an acknowledgement signal to the BCU. If the BCU does not receive the acknowledgement signal it de-activates the
volumetric sensor.
Pin No.
Description
Input/Output
1
Ground
–
2
Arm/Disarm signal
Input
3
Battery power supply
Input
4
Alarm activation
Input
M86 5979
C0666
