engine LAND ROVER DISCOVERY 2002 Workshop Manual
[x] Cancel search | Manufacturer: LAND ROVER, Model Year: 2002, Model line: DISCOVERY, Model: LAND ROVER DISCOVERY 2002Pages: 1672, PDF Size: 46.1 MB
Page 1488 of 1672
BODY CONTROL UNIT
DESCRIPTION AND OPERATION 86-3-19
Operation
For IDM inputs which are also inputs for BCU functions, the delay before the BCU recognises the change in input
status is less than 250 ms. The BCU uses a debounce algorithm to ignore changes in input having a duration less
than 100 ms with the exception of automatic gearbox W, X, Y, Z inputs, which have a debounce period of 33 ms.
Transit mode
To prevent excessive battery drain during transit to overseas markets, the vehicle is placed in a transit mode.
To exit the transit mode, simultaneously hold down the heated rear window switch and the rear fog lamp switch, turn
the ignition switch from 0 to II and, after a minimum of 2 seconds, release the switches.
Transit mode can be entered using TestBook. When TestBook communicates with the BCU for diagnostics related to
BCU operation, it first checks that the vehicle is not in transit mode.
Anti-theft system
The BCU uses the driver's door key lock and unlock switches to activate and deactivate the security system. The
driver's door lock is also used for entering the EKA.
+ ALARM SYSTEM AND HORN, DESCRIPTION AND OPERATION, Description.
Immobilisation
For immobilisation, the BCU disables the starter motor relay. When the engine is cranking, the ECM looks for a coded
signal from the BCU. If the signal is not received within one second of cranking, the fuel supply to the engine is
stopped and the injectors are disabled. This also prevents unburnt fuel from entering the catalyst.
If the BCU is disconnected, the engine starter motor will remain isolated by the starter motor relay and the ECM will
remain immobilised. The main wiring for the system is contained within the main harness which is relatively
inaccessible, so preventing intruders from disabling the system by cutting the wires for the immobilisation system.
Once the immobiliser has been activated, destruction of the trigger device or the wiring to it will not disarm the system.
The RF transmitter communicates to the BCU via the RF receiver using a 70 bit code. Pressing the unlock button on
the transmitter will re-mobilise the vehicle. The RF transponder is integrated into the metal key assembly, inserting
the key into the ignition switch will induce a signal in the exciter coil to re-mobilise the vehicle.
Anti-theft alarm
The alarm system provides a warning of unauthorised access to the vehicle and includes perimetric and volumetric
monitoring under the control of the BCU.
The perimetric protection system detects opening of all doors, tail door and bonnet and will also detect the operation
of the ignition key switch. The following conditions must be satisfied before the BCU will operate all of the functions
of perimetric protection:
lAll doors and hinged panels are in the closed position.
lIgnition key out of the ignition switch.
lInertia switch is not tripped.
If all conditions are not satisfied the BCU will enter a mislock condition.
The volumetric sensor uses two ultrasonic sensors mounted in the headlining to detect movement within the vehicle.
The alarm will trigger when the sensor signals the BCU for 200 ms or greater. Within a single setting period the alarm
system will allow a maximum of 10 triggers as a result of any combination of sensor inputs. It is possible to lock the
vehicle without enabling the volumetric alarm by using the key. The same conditions needed to satisfy enabling of the
perimetric protection system is also needed to enable volumetric protection.
Page 1493 of 1672
BODY CONTROL UNIT
86-3-24 DESCRIPTION AND OPERATION
Heated screens
The heated screen time-outs and logical operations are controlled by the BCU.
Heated front screen
The BCU provides an output to the heated front screen relay and a 'heated front screen active signal' for the heated
front screen warning lamp. The BCU uses the status of the following inputs to determine the appropriate logical
operations for this feature:
lIgnition state.
lEngine running (link from instrument pack).
lHeated front screen selected (non-latched button pressed).
If the ignition switch is not in position II, or the engine running signal is OFF, the heated front screen will not be active.
The heated front screen operation period and voltage supply is controlled by the BCU. The BCU receives a voltage
supply feed from the engine compartment fuse box and an ignition switched supply through a fuse in the passenger
compartment fuse box. When the heated front screen switch is operated, it completes a path to earth, signalling a
request for heated screen operation to the BCU. The BCU then supplies a feed to the heated front screen switch to
light the switch indicator, and earths the supply from the coil of the heated screen relay to turn the heated front screen
on. The BCU maintains a supply for a predetermined time (5 minutes), then opens the earth path after the time out
period to turn the heated screen off. During the timeout period, if the heated front screen switch is pressed a second
time, the circuit is also interrupted to turn off the supply to the heated front screen.
On vehicles fitted with air conditioning, the heated front screen is also operated by the ATC ECU when DEF (defrost)
is selected. In this case the ATC ECU provides the trigger signal to the BCU to turn the heated front screen circuit on
or, if it is already on, to re-start the time out period.
+ AIR CONDITIONING, DESCRIPTION AND OPERATION, Description.
In the event of a communications link failure occurring while the heated front screen relay is on, the relay and lamp
will remain on until the ignition switch is turned off or the time-out period elapses or the heated front screen switch is
pressed.
Heated rear window
The heated rear window will only function when the engine is running, and is operated by a non-latching switch on the
instrument pack cowl.
The BCU provides a 'heated rear window enable output' and a 'heated rear window active warning lamp signal' based
on the logic status of the following inputs:
lIgnition state.
lEngine running (link from instrument pack).
lHeated rear window selected (non-latched button pressed).
If the ignition switch is not in position II, or the engine running signal is OFF, the heated rear window will not be active.
The heated rear window operation period and voltage supply is controlled by the BCU. The BCU receives a voltage
supply feed from the engine compartment fuse box and an ignition switched supply through a fuse in the passenger
compartment fuse box. When the heated rear window switch is operated, it completes a path to earth, signalling a
request for heated rear window operation to the BCU. The BCU then supplies a feed to the heated rear window switch
to light the switch indicator, and earths the supply from the coil of the heated rear window relay via the IDM to turn the
heated rear window elements on. The BCU maintains a supply for a predetermined time (15 minutes), then opens the
earth path after the time-out period to turn the heated rear window operation off. If the heated rear window switch is
pressed a second time, the circuit is also interrupted to turn off the supply to the heated front screen.
On vehicles fitted with air conditioning, the heated rear window is also operated by the ATC ECU when DEF (defrost)
is selected. In this case the ATC ECU provides the trigger signal to the BCU to turn the heated rear window circuit on
or, if it is already on, to re-start the time out period.
+ AIR CONDITIONING, DESCRIPTION AND OPERATION, Description.
In the event of a communications link failure occurring while the heated rear window enable is on, the relay and lamp
will be de-activated.
Page 1495 of 1672
BODY CONTROL UNIT
86-3-26 DESCRIPTION AND OPERATION
If the ignition switch is in the off or crank position, the rear wipers are not active and the rear wiper enable output is
switched off.
In the event of a communications link failure occurring while the rear intermittent wipe programme is in operation, the
rear wiper enable output is switched off.
Reverse gear wipe
The BCU changes the operation of the rear wiper when the front wiper is active and reverse gear is selected. The rear
wiper operation rate used when the preconditions have been satisfied depend on the prevailing front wiper operating
mode and the position of the rear wiper switch. If the rear wiper is on or the front wiper is operating at an intermittent
rate when reverse gear is selected, the BCU will operate the rear wiper continuously for 4 seconds via the IDM. After
the initial period, the rear wiper will operate at the same rate as the front wiper.
The BCU checks for the following inputs to determine when to provide the rear wiper enable signal if the vehicle is in
reverse gear:
lIgnition state.
lRear wiper switch.
lFront intermittent wiper rate.
lReverse gear selected.
lFront intermittent wiper switch.
lFront wiper switch state.
lFront wash/ wipe in progress flag.
In the event of a communications link failure occurring while the reversing wipe is in operation, the rear wiper enable
output is switched off.
Headlamp wash
The headlamp wash will only operate when the headlamps are on, and then only every third time the front windscreen
wash button is pressed. When the BCU operates the headlamp washers, it activates the washer pump relay for a
period of 500 ms. The BCU supplies an earth path for the coil of the power wash relay located in the engine
compartment fuse box when the washer function is selected.
The BCU checks for the following inputs to determine when to provide power to the headlamp power wash relay:
lIgnition state.
lFront washer pump switch.
lDipped beam.
lMain beam state.
If the ignition switch is in the off position, the headlamp power wash relay is also held off. if the ignition state is crank,
the headlamp power wash relay is switched off and the headlamp power wash counter is reset to 0.
In the event of a communications link failure occurring while the headlamp power wash relay in on , the relay remains
on until the 500 ms timer has completed, then the relay is switched off.
Electric seats
The BCU can be programmed to operate the electric seats according to one of three options:
lOption 1 – no electric seats.
lOption 2 – normal.
lOption 3 – operates with ignition only.
To determine when to provide an output to the passenger and drivers seat enable relay, the BCU checks the condition
of the following inputs:
lIgnition state.
lTransit mode.
lDriver's door open.
Page 1498 of 1672
BODY CONTROL UNIT
DESCRIPTION AND OPERATION 86-3-29
Courtesy headlamps
This feature activates the headlamps for 30 seconds when the lock button on the remote transmitter is held down for
longer than 1 second. The headlamps will extinguish if the BCU receives either a lock or an unlock signal from the
remote transmitter.
The BCU checks the status of the following inputs to determine the correct qualifying conditions for requesting
courtesy headlamps:
lIgnition state.
lRemote locking request.
lRemote unlocking request.
lLazy locking request.
If the ignition is off and a lazy locking request is received, the courtesy headlamps are switched on and an internal
timer is turned on in the BCU which operates for 30 seconds. If the 30 second timer expires or a request for remote
locking or remote unlocking is received, the courtesy headlamps will be turned off.
When main beam is selected, the IDM also provides a signal to the instrument pack to switch on the main beam
warning lamp. An additional signal 'main beam indicator disable' is used to prevent the daylight running lamps
illuminating the main beam indicator when the main beam is in the daylight running lamp state and the main beam
indicator disable signal is on.
Lights on alarm
The lights on alarm in the instrument pack operates when the driver's door is open and the side lamps or headlamps
are on. The system uses inputs from the driver's door switch and the lighting switch to determine the logical conditions
that need to occur for switching on the alarm. The BCU carries out the logic operation and communicates with the
instrument pack using the serial data bus; the instrument pack will be requested to sound the alarm if the logic inputs
indicate that the driver's door is open with the lights still on.
Supply voltage is provided through the lighting switch to the IDM which acts as the signal line to indicate that the lights
are on for the logic circuits in the IDM and BCU. When the driver's door is opened, a second feed is supplied to the
BCU through the driver's door switch to indicate the condition. In this logic condition (lights on and driver's door open)
the BCU signals the instrument pack to operate the audible warning. If the lights are switched off or the driver's door
is closed the logic condition will be changed and the audible warning will be switched off.
Daylight running lamps
The BCU operates the daylight running lamps (where fitted) via the IDM. The daylight running lamps option can be
programmed in one of three states dependent on market/ customer requirements, these are:
lOption 1– no daylight running lamps.
lOption 2 – on with main beam off.
lOption 3 – on with main and dipped beam off and gearbox not in Park.
The BCU will ensure the logical conditions are satisfied for the lamps to operate under the set conditions. The BCU
checks the status of the following inputs to determine the logic action for providing an output to the daylight running
lamp relay:
lMain beam state.
lEngine running (link from instrument pack).
lDipped beam.
lGearbox state.
A voltage supply is fed to the coil of the daylight running lamp relay and the IDM. When the preconditions are satisfied
for daylight running lamp operation, the BCU sends a signal for the IDM to complete the circuit to earth to switch on
the daylight running lamps. The logical inputs are checked to ensure that the engine is running before switching the
relay to turn on the daylight running lamps. The engine running signal has to be present for at least 2 seconds before
the daylight running lamp relay can be switched on.
Page 1501 of 1672
BODY CONTROL UNIT
86-3-32 DESCRIPTION AND OPERATION
Odometer update
The BCU can be programmed for one of two options:
lOption 1 – no odometer error warning.
lOption 2 – odometer error warning.
In order to provide an LCD flash request to the instrument pack via the communications link, the following inputs are
checked:
lIgnition state.
lInstrument pack odometer value (via the communications link).
lBCU odometer value.
The function is only active when the ignition state is on. The maximum allowed value is 999,999 miles (1,608,999
km).If the instrument pack odometer value is greater than the maximum allowed value, the maximum value is
assumed. The BCU odometer value is stored in EEPROM. If 16 identical values of the instrument pack odometer
reading is received consecutively, the instrument pack odometer value is compared with the BCU odometer value. If
the consecutive readings from the instrument pack differ, the BCU odometer value is incremented accordingly. If the
BCU odometer value is less than the instrument pack odometer value by up to 10 km, the BCU odometer value is set
equal to the instrument pack odometer value.
If the odometer warning option is enabled, and the contents of the instrument pack odometer value buffer is identical
to, or greater than BCU odometer value
± 10 km, the BCU sends an LED flash request to the instrument pack.
In the event of a communications link failure, this function will be unable to operate.
Gear position indicator illumination
On automatic gearbox models, two variations of illumination for the gear position indicators on the selector lever can
be programmed into the BCU. In option 1, illumination is provided when the ignition is on. In option 2, illumination is
enabled when the ignition is on and the side lamps are off.
Starter relay
The BCU checks the status of the following inputs and internal BCU conditions to determine whether or not to provide
an output to enable the starter relay:
lAutostart inhibit (vehicles with automatic gearbox only).
lSecurity start inhibit (immobilisation check).
lEngine running (link to instrument pack).
lEEPROM locked (internal check).
lIDM and BCU matched.
When the BCU receives a crank signal from the ignition switch, an earth path is completed to the starter relay coil,
provided that the security system has been de-activated. If the ECM has not received a valid unlock/ remobilise signal,
the starter relay will be disengaged and the engine stopped. The BCU also receives an engine running signal from
the instrument pack, so that if the ignition key is turned to the crank position while the engine is running, the starter
motor relay will not be engaged.
If the logic conditions are correct to allow starter operation, the completion of the earth path from the starter relay coil
to the BCU energises the coil and the relay contacts close to supply battery power to the starter motor.
When the ignition switch is released from the crank position, the power supply feed from the ignition switch to the
starter relay coil is interrupted and the relay contacts open to prevent further battery feed to the starter motor.
If a communications link failure is experienced, the BCU will be prevented from detecting the 'engine running'
condition and the BCU will default to assume that the engine is not running.
Page 1513 of 1672
ALARM SYSTEM AND HORN
86-4-4 DESCRIPTION AND OPERATION
Alarm system block diagram
1Body Control Unit (BCU)
2Remote handset
3Receiver
4Fuel cut off switch
5Ignition switch
6Central door locking switch
7Volumetric sensors
8Bonnet activated alarm switch
9Drivers door key lock/unlock switches
10Door latch switches 11Fuel flap release switch
12Intelligent Driver Module (IDM)
13Battery Backed Up Sounder (BBUS)
14Alarm sounder
15Vehicle horns
16Direction indicators
17Door lock actuators
18Engine Control Module (ECM)
19Starter motor
Page 1521 of 1672
ALARM SYSTEM AND HORN
86-4-12 DESCRIPTION AND OPERATION
Passive remobilisation exciter coil
The passive remobilisation exciter coil consists of a coil around the steering column lock. The coil energises to create
a magnetic field when the ignition is switched to position II.
This coil activates the handset initiating the mobilisation of the vehicle.
Input/Output
The input to the passive remobilisation exciter coil from the BCU is a 12 volts 125 kHz sinewave. The passive
remobilisation exciter coil also receives an ignition controlled power supply via fuse 20 (15 amperes) located in the
engine compartment fuse box. On receiving these signals, a magnetic field is generated which activates the handset
to produce a remobilisation signal. This remobilisation signal is transmitted to the remote receiver and onto the BCU
to allow the engine to start.
Page 1524 of 1672
ALARM SYSTEM AND HORN
DESCRIPTION AND OPERATION 86-4-15
Anti-theft status LED
A Light Emitting Diode (LED) situated in the instrument cluster indicates the condition of the anti-theft system and acts
as a warning to potential thieves that the alarm system is activated.
Input/Output
The LED has a dedicated signal from the BCU to indicate the status of the following:
lAlarm armed: The LED flashes at 10 Hz with a 50:50 duty cycle for 10 seconds, after which the LED flashes 50
ms on, 2 seconds off until the state of the system changes.
lEngine immobilised: If the engine is immobilised and the ignition is on, the LED is illuminated continuously. If the
engine is immobilised and the ignition is off, the LED flashes 50 ms on, 2 seconds off.
lAlarm tampered: If the alarm has been triggered, the LED flashes at 10 Hz with a 50:50 duty cycle.
lHandset battery low indicator: If the handset battery is low, the driver's door is open and the ignition is switched
off, the LED flashes two pulses of 50 ms on, 50 ms off, every 10 seconds.
Page 1525 of 1672
ALARM SYSTEM AND HORN
86-4-16 DESCRIPTION AND OPERATION
Operation
Standard system functions
All vehicles have the following functions as standard.
lLocking.
lUnlocking.
lFuel cut off switch unlocking.
lInternal locking.
lElectric fuel flap release.
Locking
The doors are locked by pressing the lock button on the handset or by locking the vehicle from the driver's door with
the key.
In order to lock the vehicle, the following conditions must be met:
lThe driver's door is closed.
lThe ignition is off.
lThe fuel cut off switch is not tripped.
lThe bonnet is closed.
lThe vehicle is not super locked.
Depending on system configuration a mislock occurs if these conditions are not met. The doors may lock (depending
on condition not met) and the system may not fully arm, depending on configuration of the system. If a mislock occurs
an audible warning is emitted and the vehicle becomes partially armed.
Unlocking
The doors are unlocked by pressing the unlock button on the handset or by unlocking the vehicle from the driver's
door with the key. This may unlock only the driver's door or it may unlock all doors depending on system configuration.
Fuel cut off switch unlocking
In the event that the vehicle experiences a force strong enough to actuate the switch, all the doors on the vehicle
immediately unlock. The following conditions must be met for this to occur:
lThe security system is not armed.
lThe ignition is on.
This same action causes the fuel pump to shut off and disables the Engine Control Module (ECM). In some markets,
this action may also cause the direction indicators lights to flash.
Page 1529 of 1672
ALARM SYSTEM AND HORN
86-4-20 DESCRIPTION AND OPERATION
Mislock
Mislock alerts the driver that a failed attempt has been made to lock the vehicle because of the doors or the bonnet
not being fully closed.
There are six audible configurations for mislock:
lNo audible warning.
lAlarm sounder.
lVehicle horn.
lAlarm sounder and vehicle horn.
lBBUS.
lAlarm sounder, vehicle horn and BBUS.
When a failed attempt has been made to lock the vehicle, the audible warning device is switched on for 50 ms and
off for 200 ms. The BCU allows the audible warning device to operate 3 times.
Passive immobilisation
Passive immobilisation prevents the vehicle from being started unless the authorised key is used to start the vehicle.
There are only two configurations for passive immobilisation:
lpassive immobilisation not active
lpassive immobilisation active
When the ignition is switched off, the vehicle remains mobilised for up to a maximum of 5 minutes. If however the
driver's door is opened, after 2 minutes 30 seconds, the vehicle remains in a mobilised state for a further 30 seconds.
When the timer in the BCU has expired, the vehicle is immobilised.
Once the ignition is switched on, the BCU transmits a coded signal to the ECM. If the coded signal does not
correspond to the programmed code in the ECM, the ECM is inhibited and the BCU inhibits the starting circuit.
In order for passive immobilisation to occur, the following conditions must be met:
lDriver's door closed.
lFuel cut-off switch not tripped.
lKey not inserted in ignition.
Passive remobilisation
Whenever the vehicle is immobilised, passive remobilisation of the engine occurs when the ignition is switched on,
allowing the vehicle to be started.
There are three configurations for passive remobilisation:
lPassive immobilisation not active.
lPassive immobilisation active.
lEKA with super locking on receiving good passive remobilisation exciter coil signal.
The BCU controls the passive remobilisation exciter coil (located around the ignition barrel) to generate a magnetic
field which causes the handset to transmit a remobilisation signal. The BCU receives the signal and allows the vehicle
to be started. If a valid signal from the handset is not received within one minute of the ignition being switched to
position II, the BCU stops the passive coil from generating the magnetic field.