1999 LAND ROVER DEFENDER ECU

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DESCRIPTION AND OPERATION Volumetric Sensor
The volumetric sensor is located behind the RH’B’post on 90/110 station wagon models, on the headlining
between the interior lamp and rear view mirror on 90/110 pick-up models and on the headlining above the RH
door on 130 crewcab models.
The volumetric sensor operates by emitting a signal, which is received back to the sensor as it bounces back from
objects inside the vehicle. Once armed, the sensor will detect a disturbance to the returned waves. This is sensed
by the anti-theft alarm ECU which activates the alarm sounder or BBUS.
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DESCRIPTION AND OPERATION Alarm Sounders
1.Battery Backed Up Sounder (BBUS)
2.Alarm sounder
Two types of alarm sounder are available, dependant on the vehicle market configuration.
A Battery Backed-Up Sounder (BBUS) is used in some markets and located in the LH front wing, behind the
headlamp. This is a tamper proof sounder with its own power supply which allows it to continue operating even if
disconnected from the vehicle power supply. The BBUS is connected to a permanent battery supply via fuse 7 in
the under seat fuse box. Two further connections are made to the anti-theft alarm ECU and a fourth connection is
to an earth header. If the BBUS is disconnected without first being disarmed by the anti-theft alarm ECU, it will
operate for 4.5 minutes.
To disarm the BBUS, when the battery is to be disconnected for instance, the ignition must be turned on to
position II and back to the off position , after which a 17 second delay is initiated to allow the battery or BBUS
connector to be disconnected. If the BBUS sounds, it can be disarmed by unlocking the vehicle with the remote
handset.
Where a BBUS is not specified, a standard vehicle horn is used for the alarm sounder and is located in the LH
front wing, behind the headlamp. The sounder is operated by an alarm relay which is controlled by the anti-theft
alarm ECU. The relay receives a permanent battery supply via fusible link 6 in the under seat fuse box. The relay
coil is connected to the anti-theft alarm ECU which provides an earth for the coil when horn operation is required.
This operates the relay contacts and supplies battery voltage to the sounder, causing it to operate.
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DESCRIPTION AND OPERATION Visual and Audible Warnings
Audible and visual warnings are dependant on market legislation. The hazard warning lamps are controlled by two
outputs from the anti-theft alarm ECU; one for the LH lamps and one for the RH lamps. To illuminate the warning
lamps the output from the ECU is at battery voltage. When the lamps are off, the output is driven to earth.
When the alarm is armed the hazard warning lamps will flash three times to indicate that the system is active.
When the alarm is triggered the sounder will operate in either a pulsed or continuous tone (dependant on market
legislation) and the hazard warning lamps will flash at 0.5 second on/off intervals for 30 seconds. The alarm
system can be triggered for up to three times in any one alarm armed cycle. When the alarm system is disarmed
confirmation will be by one single flash of the hazard warning lamps for 0.3 seconds.
If the hazard warning lamps are active when an alarm trigger is active or the alarm is armed, the visual alarm
active visual warning using the hazard warning lamps will be cancelled.
In addition to the visual and audible warnings, the security LED in the instrument pack also displays alarm system
status information.
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DESCRIPTION AND OPERATION Security LED
The security LED has a number of functions to indicate anti-theft alarm system status. The LED is located in the
speedometer housing in the instrument pack. The LED receives a permanent battery supply via fusible link 6 in
the under seat fuse box. The LED is connected to the anti-theft alarm ECU which earths the connection when LED
operation is required. When the LED is not required to be illuminated, the anti-theft alarm ECU holds the
connection at battery voltage, keeping the LED extinguished.
When the system is armed and the bonnet and all doors are closed, the LED flashes quickly for a 10 second
confirmation period and confirms that perimetric and volumetric systems are armed. After the 10 second
confirmation period the LED flash changes to a slow flash to confirm that the alarm and immobiliser systems are
armed and to act as deterrent to thieves.
The LED also conveys CDL system information and this functionality is described in the Central Door Locking
(CDL) section.
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DESCRIPTION AND OPERATION Remote Handset
The remote handset is a separate unit from the vehicle key and is used to arm and disarm the alarm system. The
handset comprises two buttons; lock and unlock. The handset contains a battery (CR3032) and a printed circuit
board containing the circuitry to generate the RF signals.
NOTE: In selected markets, the vehicle key, when used in the drivers door key barrel switch, will
not disarm the alarm system.
The remote handset RF code consists of two parts. One part is a fixed code that is unique to the handset and the
second part is a rolling code which changes in accordance with a predetermined pattern. The anti-theft alarm ECU
can store the codes of up to four different remote handsets at any one time.
If the remote handset battery falls below a predetermined level, the handset will transmit an additional RF signal
code to the anti-theft alarm ECU when either button is depressed. The security LED will display this as two rapid
flashes every 0.5 seconds to visually display the low handset battery condition. This will continue for the 10
second confirmation period or until the ignition is switched on.
Resynchronisation of Remote Handset
If either the remote handset battery or the vehicle battery is removed or disconnected, the rolling part the handset
code is lost and the handset(s) need to be resynchronised to the anti-theft alarm ECU. The resynchronisation
procedure is as follows:
Disconnect the vehicle battery.
Wait for 30 seconds for residual current to dissipate.
Reconnect the vehicle battery.
Carefully prise the remote handset apart and remove the battery. Avoid unnecessary handling of the battery.
With the battery removed, press either the lock or unlock button several times to remove residual current from
the circuitry.
Check the handset battery with a voltmeter. If the battery voltage is less than 2.7 volts, replace the battery.
Ensure that the battery contact surfaces are clean and replace the battery in the handset clip with the + symbol
uppermost. Put the two halves of the handset case back together.
DO NOT press any buttons.
With the handset within range of the vehicle, press the lock button four times in quick succession. The
anti-theft alarm ECU will respond by locking the vehicle.
Press the unlock button once to complete the resynchronisation procedure.
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DESCRIPTION AND OPERATION IMMOBILISATION SYSTEM - FROM 02MY
Engine immobilisation is available on all 2002MY engine derivatives, although it is not available in selected
markets. On Td5 models, the immobilisation system is controlled directly by the anti-theft alarm ECU. On 300Tdi
models, the immobilisation system is controlled by an engine immobilisation ECU in conjunction with the anti-theft
alarm ECU.
When immobilisation occurs on Td5 models, engine crank is disabled by the anti-theft alarm ECU breaking the
earth path for the starter relay coil and the ECM disables the fuel pump relay and the glow plug relay.
When immobilisation occurs on 300Tdi models, engine crank is disabled by the anti-theft alarm ECU breaking the
earth path for the starter relay coil and the engine immobilisation ECU disables the fuel cut-off solenoid, the starter
motor solenoid and the glow plug relay.
Two types of immobilisation are available; passive and active.
Engine Immobilised Warning Lamp
The engine immobilised warning lamp is located in the instrument pack. The lamp is used by the anti-theft alarm
ECU to show that the engine is immobilised during an attempted engine start.
The warning lamp receives a battery supply from the ignition switch position I (aux) via the passenger
compartment fusebox. The anti-theft alarm ECU controls the warning lamp. When the warning lamp is not
required, the ECU supplies a battery supply to the warning lamp. When warning lamp operation is required, the
ECU provides an earth for the bulb.
If the ignition switch is moved to the crank position, but operation of the starter motor is prohibited and the engine
immobilised warning lamp flashes, then the anti-theft alarm ECU has not received the correct code from the
remote handset and the vehicle will remain immobilised. Ensure that the remote handset is in the proximity of the
transponder coil. If the remote handset is not available or inoperative, the immobilisation system can be disarmed
using the EKA procedure outlined later in this section.
If the ignition switch is turned to the crank position III and the remote handset is not in the proximity of the
transponder coil, engine immobilisation will remain active and the warning lamp will flash to inform the driver.
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DESCRIPTION AND OPERATION Passive Immobilisation
Passive immobilisation occurs when the key is removed from the ignition switch and the drivers door is opened,
after a period of 30 seconds the engine will become immobilised. If the ignition is turned off or the key is removed
from the ignition switch and drivers door is not opened, the engine will become immobilised after 5 minutes.
The passive immobilisation system operates in conjunction with the transponder coil located around the ignition
switch barrel. The transponder coil emits an electro magnetic waveform signal which excites the remote handset
into transmitting a remobilisation signal. When remobilisation is requested, the anti-theft alarm ECU transmits an
appropriate code to the ECM on Td5 models or the engine immobilisation ECU on 300Tdi models.
Active immobilisation
Active immobilisation is only invoked when the vehicle is locked using the remote handset. Active immobilisation
performs the same engine disable functionality as the passive immobilisation previously described, but includes
full CDL and activation of perimetric and volumetric alarm modes.
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DESCRIPTION AND OPERATION Emergency Key Access (EKA)
If the vehicle is in an immobilised condition and the remote handset is not available or inoperable, an EKA
procedure using the vehicle key is available to remobilise the engine systems. The EKA code is supplied with the
vehicle and is shown on the security card supplied with the owners handbook.
NOTE: This feature is only available in markets where full alarm functionality is specified.
The EKA code involves the input of a unique four digit code which is entered using the ignition switch and the
drivers door switch. Note that the alarm sounder will operate as soon as the drivers door is opened and will
continue until the sequence is successfully completed.
To enter the code (2, 3, 4, 5 for example) perform the following steps:
1.Remove the handset from the key ring and position the handset well away from the ignition switch when
entering the code.
2.Open the driver’s door and immediately insert the key in the ignition switch and turn the ignition switch to
position II. Hold this position until the alarm sounds, then switch the ignition off (position 0) and close the
driver’s door.
3.Enter the first digit of the code. Turn the ignition on (to position II) and then off twice. Open and close the
driver’s door to enter the first digit.
4.Enter the second digit. Turn the ignition on and then off, three times. Open and close the driver’s door to
enter the second digit.
5.Enter the third digit. Turn the ignition on and then off, four times. Open and close the driver’s door to enter
the third digit.
6.Enter the fourth digit. Turn the ignition on and then off, five times. Open and close the driver’s door to enter
the fourth digit. If the code has been entered correctly, the alarm LED in the instrument pack will extinguish
and the engine can be started after the last closure of the driver’s door.
If a digit is incorrectly entered, holding the ignition switch in the on position for more than 5 seconds will reset the
sequence. The code must then be re-entered from the beginning.
If the EKA code is correctly entered, the security LED will illuminate for 1 second, the immobilisation will be
disabled and the alarm sounder will cease to operate.
If the EKA code is incorrectly entered, the alarm sounder will sound twice and the correct code must be
re-entered, If the EKA code is incorrectly entered three times the system invokes a 30 minute lockout. This is
signalled by the LED flashing with a long illuminated period followed by a short extinguished period for the lockout
duration.
NOTE: Disabling the alarm and immobilisation system using the EKA procedure is only valid for
one ignition on/off cycle. When the ignition is switched off, the immobilisation system will be
activated after a period of 30 seconds. If the remote handset is still unavailable, the EKA
procedure will have to be repeated each time the vehicle is to be driven.
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