fuse LAND ROVER DISCOVERY 1999 Workshop Manual

INSTRUMENTS
DESCRIPTION AND OPERATION 88-31
Seat belt warning lamp
The seat belt warning lamp within the instrument pack utilises a red LED and a clear legend. The BCU utilises a switch
in each of the front seat belt buckles to determine if a seat belt is not fastened.
When the ignition is switched on, the BCU illuminates the LED for 6 seconds or until the BCU determines that a seat
belt is fastened which extinguished the warning lamp. This provides the driver with a visible reminder that the seat
belts are not fastened.
The instrument pack provides the self-check if the diagnostic connector fails.
The power input for the LED is supplied by the instrument pack via fuse 13. The BCU provides the earth path to
illuminate the seat belt warning lamp.
The seat belt buckle switches complete the earth path in the BCU sensing circuit, the BCU commands the instrument
pack to switch on the seat belt warning lamp.
The BCU earth path to the seat belt buckle is as follows:
l< 1.8 volts = warning lamp off.
l> 7.7 volts = warning lamp off.

INSTRUMENTS
88-32 DESCRIPTION AND OPERATION
Transmission high temperature warning lamp
The transmission high temperature warning lamp within the instrument pack utilises a red LED and a clear legend.
On vehicles fitted with automatic gearboxes, the transmission high temperature warning lamp is utilised to provide the
driver with a visible warning that the automatic gearbox oil has exceeded a normal operating temperature. The
warning lamp will extinguish if the gearbox oil returns back to normal operating temperature.
When the ignition is switched on, the instrument pack illuminates the LED to provide a self-check, providing there is
no fault it will remain illuminated for 3 seconds or until the ignition is switched off.
The power input for the LED is supplied by the instrument pack via fuse 13. The temperature sensor provides the
earth path to illuminate the transmission high temperature warning lamp.
The transmission high temperature warning lamp is controlled according to the voltage present on the temperature
sensor to instrument panel earth path:
l< 1.8 volts = warning lamp on.
l> 7.7 volts = warning lamp off.

INSTRUMENTS
DESCRIPTION AND OPERATION 88-33
Engine oil pressure warning lamp
The engine oil pressure warning lamp within the instrument pack utilises a red LED and a clear legend. The LED
illuminates when the engine oil pressure is below the specified pressure (see table), providing the driver with a visible
warning that the engine oil pressure has fallen below the specified minimum reading.
There is no self-test performed at ignition on for this warning lamp.
The power input for the LED is supplied by the instrument pack via fuse 27. The oil pressure switch located on the
engine provides the earth path to illuminate the warning lamp, it will remain illuminated until the engine is started and
the oil pressure exceeds the appropriate threshold and opens the switch contacts.
Low oil pressure switch operating pressures
The response to the voltage signal at the instrument pack is as follows:
l< 1.8 volts = warning lamp on.
l> 7.7 volts = warning lamp off.
Engine type Switch opening pressure, bar (lbf.in2)
V8 0.22 to 0.59 (3.0 to 8.5)
Diesel 0.25 to 0.42 (3.5 to 6.0)

INSTRUMENTS
88-34 DESCRIPTION AND OPERATION
Alternator charge warning lamp
The alternator charge warning lamp within the instrument pack utilises a red LED and a clear legend. The LED
illuminates when the alternator output voltage is less than 2 volts. When the alternator output is greater than 7.6 volts
the LED is extinguished, providing the driver with a visible warning that the alternator is charging.
When the ignition is switched on, and the LED illuminates, it will remain illuminated until the engine is started and
voltage is above the predetermined parameter, or the ignition is switched off providing there is no fault.
The power input for the LED is supplied by the instrument pack via fuse 27. The alternator provides a signal to
illuminate the warning lamp by means of a hard wired connection to the instrument pack.
The response to the voltage signal at the instrument pack is as follows:
l< 2.0 volts = warning lamp on.
l> 7.6 volts = warning lamp off.

INSTRUMENTS
DESCRIPTION AND OPERATION 88-35
Hill Descent Control (HDC) fault warning lamp
The HDC fault warning lamp within the instrument pack utilises an amber LED and a clear legend. On vehicles fitted
with hill descent control the SLABS ECU illuminates the LED if a fault within the HDC system is detected, providing
the driver with a visible warning.
When the ignition is switched on, the SLABS ECU illuminates the LED to provide a self-check, it will remain illuminated
for 3 seconds or until the ignition is switched off, providing there is no fault.
The power input for the LED is supplied by the instrument pack via fuse 27. The SLABS ECU provides the earth path
to illuminate the HDC fault warning lamp
The voltage on the earth path from the SLABS ECU to the instrument pack has the following functions:
l< 1.8 volts = warning lamp is switched on.
l> 7.7 volts = warning lamp is switched off.

INSTRUMENTS
88-36 DESCRIPTION AND OPERATION
Self Levelling Suspension (SLS) warning lamp
The SLS warning lamp within the instrument pack utilises an amber LED and a clear legend. The SLABS ECU
illuminates the LED continuously if a fault within the SLS is detected, providing the driver with a visible warning.
When the ignition is switched on the SLABS ECU illuminates the LED to provide a self-check, providing there is no
fault it will remain illuminated for 3 seconds or until the ignition is switched off.
On vehicles equipped with coil springs the SLS warning lamp is extinguished after 850 milliseconds if the SLABS ECU
configuration of the vehicle is correct.
The SLS warning lamp flashes at 2 Hz when the remote handset control is used to raise or lower the ride height.
If a new SLABS ECU is installed the SLS warning lamp will remain illuminated until the ECU has been calibrated by
TestBook.
The warning lamp will illuminate continuously when battery voltage is less than 10 volts for greater than 1 second.
When the vehicle is in transportation mode the SLS warning lamp is illuminated continuously with ignition on, and will
flash at 2 Hz frequency as the vehicle rises from bump stop level to transport level on engine start.
The power input for the LED is supplied by the instrument pack via fuse 27. The SLABS ECU provides the earth path
to illuminate the warning lamp.
The voltage on the earth path from the SLABS ECU to the instrument pack has the following functions:
l< 1.8 volts = warning lamp on.
l> 7.7 volts = warning lamp off.

INSTRUMENTS
DESCRIPTION AND OPERATION 88-37
Active Cornering Enhancement (ACE) warning lamp
On vehicles fitted with ACE an LED within the instrument pack is used to alert the driver that the ACE ECU has
detected a fault in the system, providing the driver with a visible warning. The ACE warning lamp utilises an amber
LED and a clear legend.
When the ignition is switched on the ACE ECU illuminates the LED to provide a self-check, providing there is no fault
it will remain illuminated for 3 seconds or until the ignition is switched off.
The power input for the LED is supplied by the instrument pack via fuse 13. The ACE ECU provides the earth path to
illuminate the warning lamp.
The voltage on the earth path from the ACE ECU to the instrument pack has the following functions:
l< 1.8 volts = warning lamp on.
l> 7.7 volts = warning lamp off.

INSTRUMENTS
DESCRIPTION AND OPERATION 88-39
Anti-theft status warning lamp
The anti-theft status warning lamp within the instrument pack utilises a red LED and a clear legend.
The BCU illuminates the LED when the vehicle anti-theft system is active.
This provides a warning to potential thieves that the vehicle is protected by a security system.
When the ignition is switched on, the ECM illuminates the LED to provide a self-check, providing there is no fault it
will remain illuminated until the engine is started or the ignition is switched off.
The power input for the LED is supplied by the instrument pack via fuse 13. The BCU controls the earth path to
illuminate the warning lamp.
The voltage on the earth path from the BCU to the instrument pack will be less than 1 volt when the anti-theft status
is enabled.

INSTRUMENTS
88-40 DESCRIPTION AND OPERATION
Audible warning speaker
The audible warning speaker is integral with the instrument pack and provides an audible warning to alert the driver
of the following situations:
lSeat belt warning lamp.
lKey in/lights on warning.
lSLABS command received warning.
lTransfer box in neutral warning.
lLights on warning.
It has a maximum pressure level of 87 dB at 1 metre (3.3 ft). The audible warning speaker is located on the rear of
the instrument pack.
The power input for the audible warning speaker is supplied by the instrument pack via fuse 27.
The BCU provides the earth paths for the following:
lThe seatbelt warning.
lKey in/lights on warning.
lLights on warning.
The SLABS ECU provides the earth paths for the SLABS commands. The EAT ECU provides the earth path for the
transfer box in neutral warning.
The BCU activates the audible warning speaker to produce audible warnings.
The audible warning speaker can operate with the ignition off.
The seatbelt warning will commence at key on, and in the event of a serial link failure, will terminate after 6 seconds.
The SLABS warnings are sounded only once for each received command.
The lights on warning and transfer box in neutral are sounded continuously until a sound off command is received.
Sound request number Sound functions Priority (1 = lowest, 6 = highest)
0Off 1
1 Seat belt warning 6
2Key-in warning 3
3 SLABS/ HDC warning 4
4 Transfer box in neutral warning 5
5 Lights on warning 2

INSTRUMENTS
88-42 DESCRIPTION AND OPERATION
Interior rear view mirror with compass
(where fitted)
1Cover
2Electrical connector
3Mounting bracket
4Light sensor5Compass LED display
6Compass calibration switch
7Compass printed circuit board
Certain vehicles have an interior rear view mirror that features an automatic photochromatic dimming function and an
electronic compass with LED display.
The compass mirror is a self-contained unit and does not interface with any other vehicle system or electronic control
unit. The mirror is fixed to a metal bracket attached to the windscreen.
A three pin connector provides the electrical connection to the mirror's internal circuit board. Pin-1 of the connector
provides the 12V power supply to the board via the auxiliary relay located in the engine compartment fusebox. When
the ignition switch is turned to the 'II' position, a 12V supply is provided to energise the coil of the auxiliary relay via
fuse 26 in the passenger compartment fusebox. The auxiliary relay's contact supply voltage is provided from the
vehicle battery through fusible links 1 & 7. When the relay's contacts close, a 12V supply is fed to the compass mirror
circuit board via fuse 15 in the passenger compartment fusebox. This is the supply voltage feed for the mirror's internal
compass.
Pin-2 of the electrical connector provides the path to earth.
Pin-3 of the electrical connector is a 12V ignition switched supply voltage (position 'II' of the ignition switch). The
supply voltage is provided to the mirror's circuit board via fuse 25 in the passenger compartment fusebox, and the
reverse lamp switch (normally closed) for vehicles with manual transmission or the starter inhibitor / reverse light
switch (normally closed) for vehicles with automatic transmission. This is the supply voltage feed for the mirror's
photochromatic dimming function.
M88 0297
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