Range Rover Body Control Unit: Car/Key Memory Details
BODY CONTROL UNIT
86-3-2
DESCRIPTION AND OPERATION
Description
General
The Body Control Unit (BCU) centralises the control of several body systems, reducing electrical complexity and
increasing overall system reliability. The BCU controls the routines of the following systems:
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Anti-theft alarm system (see Security section)
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Car/Key Memory
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Central door locking and child safety lock (see Security section)
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Door mirror control (see Body section)
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Headlamp wipers and washers (see Wipers and Washers section)
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Interior lighting (see Lighting section)
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Load disconnection
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Sunroof (see Body section)
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Approach Lamps (see Lighting section)
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Window regulators (see Windows section)
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Windshield wipers and washers (see Wipers and Washers section).
The vehicle type, equipment configuration and market specific features are specified to the BCU by means of coding
data via the diagnostics interface.
Load switching circuits for currents < 10 A consist of semiconductor switches within the BCU. The load switching
circuits for the headlamp and windshield wipers are subjected to a greater degree of loading (number of operating
cycles and current loading), so the switching is performed outside the BCU by relays.
Car/Key Memory
The car memory contains vehicle function settings that can be changed to suit market and customer preferences. In
some markets, some of the functions in the car memory are blanked out due to marketing and statutory requirements.
Where available, the settings can be changed using TestBook/T4.
The key memory is based on the car memory, and contains function settings that can be personalised to an individual
driver. Different drivers are recognised indirectly through the remote control transmitter in the key. Up to four different
keys can be recognised by the BCU. The key memory settings can be changed using TestBook/T4.
The BCU broadcasts driver recognition on the P bus and the K bus to the following control modules, which also
contain personalised key memory settings:
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Driver door module, for memorised door mirror settings
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Memory seat ECU, for memorised driver's seat and steering column settings
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Radio, for memorised tone, audio source and station settings.
The driver recognition messages contain the key number, the button pressed on the remote control and whether the
key is valid or not. The key number is contained in the unlock transmission of the remote control keys, so personalised
settings are only recalled after the vehicle has been unlocked with the remote control of one of the key numbers stored
in the key memory. If the vehicle is unlocked with the key in the driver's door lock, the BCU identifies the key as invalid
and control modules with personalised settings recall the last used setting. The BCU outputs the driver recognition
message when it detects:
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An 'unlock' command from a remote control (the signal is sent immediately so that the correct positions for seat,
door mirrors and steering column can be set)
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Any other actuation by remote control (when the remote control 'lock' command is detected, seat motion to a
memorised position is stopped)
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Operation of the central locking system by other than a remote control
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A change of state of the ignition switch
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A driver recognition enquiry from another control module.
The seat and steering column memories are coded with an automatic movement option for the driver's seat, door
mirrors and steering column. The options are:
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No automatic setting
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Automatically setting the positions in response to the remote control 'unlock' command
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Automatically setting the positions in response to the remote control 'unlock' command and opening of the
driver's door.
