1995 LAND ROVER DISCOVERY open bonnet

ELECTRICAL
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DESCRIPTION AND OPERATION Radio frequency system
The RF system uses four frequencies according to
market. If the coaxial aerial is not fitted system
performance will be impaired. Both ECU and handset
have a colour coded label.
Frequency Colour Territory
ECU/Handset
433.92 MHz Blue/black........................... UK, Ireland........................
224.5 MHz, Yellow/yellow............................ France...................
433.92 MHz Blue/Purple........................... Germany......................
433.92 MHz Blue/blue........................... Europe, not France, Switzerland, Italy, Denmark,..........................
Germany
433.92 MHz White/Blue........................... Switzerland, Denmark.......................
315.0 MHz Green/green............................. Rest of world, Italy, Australia....................
315.0 MHz Orange/Green............................. Gulf, Japan..................
Partially armed mode
If a door, tailgate or bonnet [hood] is left open when
the system is armed, the LED will not light for 10
seconds indicating a mislock condition. Hazard lights
will not flash. If an open door or tailgate is causing the
mislock, the starter motor is disabled. The alarm will
sound if ignition is turned to start position. If an open
bonnet [hood] is causing the mislock the starter motor
is disabled. The alarm will arm the volumetric part of
the system. If the door tailgate or bonnet [hood] is
subsequently closed, after a 5 second delay, the
doors will unlock and immediately lock and the system
will fully arm.
Handset transmitter
The handset LED will give one short flash when
button is pressed momentarily.
If button is held down the LED will light again after 2
seconds for 2 seconds, and extinguish until button is
released and repressed. The handset contains unique
information distinguishing it from other transmitters. It
also contains a set of 'random' rolling codes
programmed into the ECU before leaving the factory.
Each time the handset is pressed a different code is
transmitted to the ECU.
If handset is operated more than four times outside
the vehicle range (6 metres) or power supply is
removed, it will be necessary to re-sychronise handset
and the ECU by pressing the handset three times
within range and within 5 seconds.
NOTE: If both handsets are lost or
damaged when system is armed it will be
necessary to fit a new ECU with two
matching handsets.
Handset batteries
If handset LED flashes continuously when button is
pressed, the batteries need replacing. The hazard
lights will flash one 3 second pulse, instead of three
times upon arming vehicle.
Power up mode
The alarm system always remembers the state it was
left in when power was removed. If the alarm powers
up in an armed state and is subsequently triggered it
will give a warning that it will fully trigger unless
disarmed. This warning consists of short horn pulses
every two seconds for 15 seconds.
New born mode
When the ECU is first produced, it will be in its 'new
born' mode. In this mode it will respond to any remote
of the right frequency. This mode will be cancelled
when the ECU has received ten valid handset signals
without power interruption.
Engine cranking
It is only possible to crank the engine when ignition is
ON and alarm disabled.

86ELECTRICAL
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DESCRIPTION AND OPERATION BUILT IN TEST PROCEDURE
The built in test procedure is accessed as follows:
1.Starting conditions: ignition off, doors unlocked,
bonnet [hood] switch depressed.
2.Carry out instructions 3 to 7 within 8 seconds.
3.Release bonnet [hood] switch.
4.Switch ignition ON.
5.Lock doors.
6.Switch ignition OFF.
7.Switch ignition ON.
If alarm is correctly accessed, horn will sound and
LED will flash. The following checks can be made:
8.Open and close any door or tailgate - LED will
light.
9.Depress bonnet [hood] switch - hazards will
flash.
10.Check engine cranking is disabled. Do not turn
off ignition.
11.Check ultrasonic by operating handset, LED will
emit one 5 second flash, and will flash if interior
is disturbed.
NOTE: If ECU is new born mode any
handset of the right frequency will work. If
not an initialised handset is required see
Handset Initialisation.
12.Turn OFF ignition or press handset to end test
procedure. Horn will sound as before to indicate
end of test mode.

86ELECTRICAL
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DESCRIPTION AND OPERATION DETECTION COMPONENTS
Switches
Perimetric protection for the vehicle is provided by
ECU inputs connected to the following:
Key switches (including starter)
Sill buttons
Bonnet switch
Door switches
Ultrasonic sensor
The ultrasonic sensor is located on the interior light
switch panel and triggers the alarm if movement is
detected.
WARNING INDICATORS
Battery backed-up sounder
The battery backed-up sounder is located in the
engine compartment and provides an audible warning
whenever the alarm is triggered.
NOTE: Disconnecting the vehicle battery
will result in the alarm sounding if the
correct procedure has not been followed.
See Repair, Battery.
Engine immobilisation warning light (EIWL)
The engine immobilisation warning light is located in
the instrument pack and provides a visual indication
that the engine is immobilised.
Anti-theft alarm indicator light
The anti-theft alarm indicator light is located in the
instrument pack and provides a visual indication of the
alarm status.
Inertia switch and central door locking
As a safety feature, the alarm system is designed to
recognise the inertia switch and via the ECU, unlock
the doors in the event of a collision.
NOTE: This feature only applies when the
starter switch is in the on position.ANTI-THEFT ALARM OPERATION (96 MODELS)
Full arming and immobilisation
Locking the vehicle using the handset immobilises the
engine and initializes both volumetric and perimetric
protection, providing:
1.After a lock signal has been received, a period of
15 seconds has elapsed during which no
movement is detected inside the vehicle;
2.No door or bonnet is open.
NOTE: If either of the above conditions are
not satisfied, the alarm will only be
partially armed. This is a mislock condition
which will be made apparent by a delay of 10
seconds before the anti-theft alarm indicator
begins to flash.
Disarming the alarm
NOTE: ALWAYS disarm the alarm using
the handset.
Unlocking with the key will not disarm the alarm or
mobilise the vehicle. If the handset fails to unlock the
vehicle
See Repair, Handset.
Partial arming and immobilisation
The alarm will be partially armed and the engine
immobilised if the vehicle is locked with the handset or
key, if:
1.After a lock signal has been received, a period of
15 seconds has elapsed during which movement
is detected inside the vehicle;
2.A door or bonnet is open.
NOTE: This is a mislock condition which
will be made apparent by a delay of 10
seconds before the anti-theft alarm
indicator begins to flash. Subsequent closure of
the offending aperture will cause the alarm to
attempt full arming as previously described.
Immobilisation
The vehicle will be automatically immobilised
whenever any of the following conditions occur:
1.The vehicle is locked using the handset.
2.The vehicle is locked using the key.
3.Thirty seconds after the starter switch has been
turned off AND the driver's door opened.
4.Five minutes after the starter switch is turned off
or the alarm disarmed.

ELECTRICAL
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DESCRIPTION AND OPERATION ANTI-THEFT ALARM BUILT-IN TEST (96 MODELS)
NOTE: The handset should be detached
from the key to allow perimetric testing of
the alarm system. The system will
automatically switch to volumetric testing if the
handset is in close proximity to the starter switch.
The built-in test procedure can be accessed providing
the following conditions exist:
Alarm disarmed.
Ignition off.
Doors unlocked.
Bonnet[hood] closed.
The test mode can be entered by completing the
following instructions within 5 seconds:
1.Open bonnet.
2.Turn starter switch on.
3.Open driver's door (far enough to activate
switch).
4.Turn starter switch off.
5.Turn starter switch on.
If the test mode has been correctly accessed, the
sounder/horn will operate briefly and the anti-theft
alarm indicator and hazard warning lights will flash.
Perimetric tests
The anti-theft alarm indicator light and the hazard
warning lights will flash when:
1.Door switches are activated;
2.The bonnet is opened;
3.Sill switches are activated;
4.Key switches are activated.
NOTE: Operation of key switches can be
verified by turning the key in the relevent
direction so as not to simultaneously
activate the sill switch. If the key switch changes
state, the change should be detected but the sill
switch will not be activated.
Volumetric tests
Press the unlock button or move the handset close to
the starter switch to disable perimetric testing and
enable volumetric testing. If movement is detected
within the vehicle by the ultrasonic sensor it will be
indicated by flashing the anti-theft alarm indicator and
hazard warning lights.
NOTE: Exit anti-theft alarm built-in test by
turning starter switch to the off position.

ELECTRICAL
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FAULT DIAGNOSIS GENERAL INFORMATION
The electrical fault diagnostic tool on Discovery
vehicles is Testbook. Detailed information of electrical
systems, component locations and circuit diagrams
are covered in the Discovery Electrical
Troubleshooting Manual.
See INTRODUCTION,
Information, Fault Diagnostic Equipment
This section covers checks of the charging and
ignition system.
GENERATOR TESTING
Service repair no - 86.10.01
Charging system check
1.Check battery is in good condition, with an open
circuit voltage of at least 12.6 V. Recharge or
substitute battery to carry out test.
2.Check drive belt condition.
See SECTION 10,
Maintenance, Under Bonnet [Hood]
Maintenance
3.Check battery connections are clean and tight.
4.Check generator connections are clean and
tight.
5.Ensure there is no drain on battery from, for
example, interior, under bonnet [hood] or door
edge lamps.
Generator test
Following instructions refer to use of suitable test
equipment using a carbon pile rheostat.
6.Connect test equipment referring to
manufacturer's instructions.
7.Start engine and run at 3000 rev/min without
accessory load.
8.Rotate carbon pile load control to achieve
greatest output (amps) without allowing voltage
to fall below 12.0 V. A reading in amps, of
generator output, minus 10% to allow for EFI
and Ignition loss, should be obtained.
9.Run engine at 3000 rev/min, switch selector to
regulator test, read voltmeter. A reading of 13.6
to 14.4 V should be obtained.
10.Switch selector to diode/stator test, switch on
headlamps to load generator. Raise engine
speed to 3000 rev/min, read voltmeter, needle
must be within 'OK' range.TESTING IN POSITION
Charging circuit resistance test.
1.Connect a low range voltmeter between
generator terminal marked B+ and positive
terminal of battery.2.Switch on headlamps, start engine. Run engine
at approximately 3000 rev/min. Note voltmeter
reading.
3.Transfer voltmeter connections to frame of
generator and negative terminal of battery, and
again note voltmeter reading.
4.If reading exceeds 0.5 volt on positive side or
0.25 volt on negative side, there is a high
resistance in charging circuit which must be
traced and remedied.