Body Control Unit Land Rover Range Rover III

Scheme 1

General

The Body Control Unit (BCU) centralizes the control of several body systems, reducing electrical complexity and increasing overall system reliability. The BCU controls the routines of the following systems

1. Anti-theft alarm system (see «SECURITY»(/land-rover/range-rover/iii-2002-2005/remont/door-locks-anti-theft-systems/#security) )
2. Car/Key Memory
3. Central door locking and child safety lock (see «SECURITY»(/land-rover/range-rover/iii-2002-2005/remont/door-locks-anti-theft-systems/#security) )
4. Door mirror control (see «76.11.10 MIRROR -- EXTERIOR»(ref-208059-S36935253232005120200000) )
5. Headlamp wipers and washers (see «HEADLAMP WIPERS AND WASHERS»(/land-rover/range-rover/iii-2002-2005/remont/sun-rooft-topconvertible-top/#wipers-and-washers-description-operation__headlamp-wipers-and-washers) )
6. Interior lighting (see «LIGHTING»(/land-rover/range-rover/iii-2002-2005/remont/exterior-lights/#lighting-description-operation) )
7. «LOAD DISCONNECTION»(/land-rover/range-rover/iii-2002-2005/remont/memory-modules/#body-control-unit__load-disconnection)
8. Sunroof (see «SUNROOF»(/land-rover/range-rover/iii-2002-2005/remont/sun-rooft-topconvertible-top/#sunroof-description-operation) )
9. Approach Lamps (see «LIGHTING»(/land-rover/range-rover/iii-2002-2005/remont/exterior-lights/#lighting-description-operation) )
10. Window regulators (see «WINDOWS»(/land-rover/range-rover/iii-2002-2005/remont/windows/#windows-description-operation) )
11. Windshield wipers and washers (see «WIPERS AND WASHERS»(/land-rover/range-rover/iii-2002-2005/remont/sun-rooft-topconvertible-top/#wipers-and-washers-description-operation) ).

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.

CarKey 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 T4.

The key memory is based on the car memory, and contains function settings that can be personalized 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 T4.

The BCU broadcasts driver recognition on the P bus and the K bus to the following control modules, which also contain personalized key memory settings

1. Driver door module, for memorized door mirror settings
2. Memory seat ECU, for memorized driver's seat and steering column settings
3. Radio, for memorized 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 personalized 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 personalized settings recall the last used setting. The BCU outputs the driver recognition message when it detects

1. 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)
2. Any other actuation by remote control (when the remote control 'lock' command is detected, seat motion to a memorized position is stopped)
3. Operation of the central locking system by other than a remote control
4. A change of state of the ignition switch
5. 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

1. No automatic setting
2. Automatically setting the positions in response to the remote control 'unlock' command
3. Automatically setting the positions in response to the remote control 'unlock' command and opening of the driver's door.

Automatic movement of the seat can be stopped by pressing the remote control 'lock' button or any of the seat adjustment or memory switches. Automatic movement can be restarted by pressing the remote control 'lock' button again. Pressing the 'unlock' buttons (for selective central locking) and 'unlocking the boot' does not stop automatic seat movement.

Storage of personalized settings is automatically updated for each setting change provided a valid remote control key has been detected (interruption of the automatic recall movement of the driver seat, door mirrors and steering column is not interpreted as a setting change). The last setting for the recognized driver is automatically stored in the key memory area of the corresponding control module. If no valid remote control key has been detected, setting changes are stored in a recall memory for retrieval when an invalid key is detected.

The following table contains the car and key memory functions that can be changed (depending on market) using T4.

KEY MEMORY FUNCTIONS CHART

Load Disconnection

The BCU supplies various electrical loads on the vehicle, such as the glovebox lamp, reading lamps, luggage compartment lamps, etc., that can be switched on and remain on when the vehicle is parked. A central load disconnection feature in the BCU ensures the battery is not discharged in the event these loads are switched on continuously. The trigger time after the ignition is switched off is 16 minutes and is independent of the sleep mode timer.

The BCU also disconnects the following loads while the engine cranks, to maximize the available power from the battery

1. Wipers
2. Washer pump
3. Headlamp cleaning
4. Window regulators
5. Sunroof.

If the one-touch function of a window or sunroof is active before the load disconnection, the function is not continued when engine cranking stops.

Sleep Mode

To conserve power, the entire BCU goes into a 'sleep' mode 16 minutes after signal activity ceases and the ignition is switched off. The typical current consumption of the BCU in sleep mode is 1.25 mA. In the sleep mode the BCU is in a limited operational mode from which it can be awakened by certain relevant wake-up signals. After being awakened, the BCU remains awake for 1 minute if no action is triggered. If an action is triggered, the BCU remains awake for at least 16 minutes.

The BCU wakes up when it receives a signal from any of the following

Scheme 2

Scheme 3

Scheme 4

Scheme 5

1. The K bus
2. Any door status switch (driver, front passenger, LH and RH rear doors)
3. Bonnet status switch
4. Central door locking switch
5. Driver's door lock cylinder lock switch
6. Driver's door lock cylinder unlock switch
7. Interior lamp switch
8. Lower tail gate opening switch
9. Tilt alarm sensor
10. Ultrasonic sensor
11. Upper tail gate opening switch
12. Upper tail gate status switch.

Diagnostics

Diagnostic monitoring is included in the operating software of the BCU and is performed on a continual basis. All of the input and output signals which are relevant for diagnostics can be read out and injected using T4. Detected faults are stored in the non volatile memory (EEPROM) of the BCU.

All faults stored by the BCU are stored chronologically, with a fault counter, in a fault or information area of the memory. Faults which positively point to one or more defective components are stored in the fault area. Faults which do not positively point to a defective component are stored in the information area to provide information during troubleshooting. The BCU ignores faults detected within 32 seconds of power up or when battery voltage is less than 9 V.

A distinction is made between sporadic and static faults. Sporadic faults are those which have occurred at least once, and the cause of the fault message was no longer present at least one time. Static faults are faults which are still active at the time diagnostics are performed.

The BCU can store up to 30 faults at any one time. If further faults are detected following the 30th fault they are ignored. Faults can only be erased using T4.

Up to 16 faults stored by the BCU are also stored in those modules connected to the BCU via the P bus, i.e. the driver and passenger door modules and the sunroof module. Faults stored in the peripheral modules cannot be accessed via the diagnostic socket. The faults in the peripheral modules are used for diagnosing modules after they are removed from the vehicle.

See also:
• SECURITY
• HEADLAMP WIPERS AND WASHERS
• LIGHTING
• SUNROOF
• WINDOWS
• WIPERS AND WASHERS
• LOAD DISCONNECTION