Land Rover Discovery 99my To 03my Electrical Library 3rd Edition Rover Manual

							DESCRIPTION AND OPERATION
4.140DISCOVERY SERIES II
Transfer box in neutral warning lamp (if fitted)
The transfer box in neutral warning lamp is connected on an SK wire from the instrument 
pack pin C0233-16 via header C0293 LHD/ C0292 RHD to pin C0661-1 on the BCU. This 
connection is the serial data bus between the instrument pack and the BCU.
Refer to the Workshop Manual Transfer Box - LT 2305E for detailed Description and 
Operation of the transfer box in neutral warning lamp.
Main beam warning lamp
The main beam warning lamp is connected from the instrument pack pin C0230-3 on a US 
wire to the IDM in the passenger compartment fusebox.
Refer to the head/side and number plate lamps section of this manual for details of 
operation.
Anti theft alarm LED
The anti theft alarm LED is connected from the instrument pack pin C0233-8 on a BS wire 
to pin C0661-20 on the BCU.
Refer to the Workshop Manual Alarm System for Description and Operation of the anti-theft 
system.
Active Cornering Enhancement (ACE) warning lamp
The ACE warning lamp is connected from the instrument pack pin C0233-1 on a BO wire to 
pin C0647-36 on the ACE ECU.
Refer to the Workshop Manual Front Suspension for Description and Operation of the ACE 
system.
Differential lock warning lamp
The differential lock warning lamp is connected from the instrument pack pin C0230-8 on a 
BU wire via header C0761 to the differential lock unit. A feed from fuse 25 is sent by a GY 
wire through a resistor unit on pin C0038-1 and to the differential lock unit on a WN wire from 
pin C0037-2
If an earth path is completed on pin C0230-8 the instrument pack logic circuit monitors this 
as an input and provides power from the ignition supply to illuminate the warning lamp.
The ABS system controls the operation of the centre differential lock, refer to Workshop 
Manual Brakes Description and Operation for further details. 
						

							DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.141
Transmission oil warning lamp
The transmission oil warning lamp is connected from the instrument pack pin C0230-7 on a 
BLG wire to header C0293. BLG wires from header C0293 are connected to the 
transmission oil temperature sensors. The sensors are located in the gearbox oil cooler and 
the rear of the transfer gearbox.
If an earth path is completed on pin C0230-7 the instrument pack logic circuit monitors this 
as an input and provides power from the ignition supply to illuminate the warning lamp.
Fuel warning lamp
The instrument pack internal logic circuits monitors the resistance value of the fuel gauge 
circuit. The warning lamp will be illuminated via an internal supply from the ignition circuit if 
the value stored in the instrument pack memory is reached.
Sport and manual warning lamps (automatic vehicles only)
The sport warning lamp is connected from pin C0230-4 of the instrument pack on a YR wire 
to pin C0193-25 on the Electronic Automatic Transmission (EAT) ECU. The manual warning 
lamp is connected from pin C0230-5 of the instrument pack on a YG wire to the pin C0193-
51 of the EAT ECU.
Both lamps are illuminated by the input from the EAT ECU and are earthed via the 
instrument pack. The EAT ECU sends an input to the lamps to indicate the EAT operating 
mode.
Refer to the Electronic Automatic Transmission (EAT) section of this manual for details of 
operation.
Speedometer - vehicles with ATC
The instrument pack is connected from pin C0230-16 on a KG wire via splice joint A87 and 
header C0290 to pin C0504-3 on the SLABS ECU. The SLABS ECU sends a speed signal 
to the instrument pack via this connection.
Speedometer - vehicles without ATC
The instrument pack is connected from pin C0230-16 on a KG wire via header C0290 to pin 
C0504-3 on the SLABS ECU. The SLABS ECU sends a speed signal to the instrument pack 
via this connection.
Overspeed warning
The overspeed warning lamp is connected from the SLABS ECU as described for the 
speedometer. The instrument pack software monitors the road speed signal supplied to the 
instrument pack on pin C0230-16. The warning lamp is illuminated at speeds of 78 mph 
(125.5 km/h) or above and extinguished at 74 mph (118.5 km/h). 
						

							DESCRIPTION AND OPERATION
4.142DISCOVERY SERIES II
Coolant temperature gauge
The coolant temperature gauge is connected from pin C0233-15 on a GU wire to the ECM 
pin C0636-44 V8/C0658-7 Td5.
Refer to the engine management section in the workshop manual for details of operation.
Tachometer
The tachometer gets an engine speed signal via pin C0230-15 of the instrument pack. Pin 
C0235-15 is connected on a WS wire via header C0291 to pin C0637-17 V8/C0658-19 Td5 
on the ECM.
Refer to the engine management section in the workshop manual for details of operation.
Fuel gauge
The fuel gauge is connected from pin C230-14 of the instrument pack to the fuel tank unit 
on a GB wire. The fuel tank unit sends an earth input on a KB wire to pin C0230-13 on the 
instrument pack. The fuel tank unit sender is of the variable resistance type and the fuel 
gauge displays a value according to the input sent from the fuel tank unit sender. 
						

							DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.143
HORNS
DESCRIPTION
General
Two horns are located in the left and right hand sides of the front panel, forward of the 
radiator. The horns are operated by pushing either of two buttons located on the upper 
spokes of the steering wheel. One horn emits a low tone, the other a high tone. Each horn 
produces a sound of between 93 and 112 db at a distance of 7 m (23ft).
Each horn switch is connected to the horn circuit via a rotary coupler in the steering column. 
The horn circuit is on a permanent feed from the battery and operates independently of the 
ignition circuits.
OPERATION
Horns Supply
Circuit supply
A feed from the battery positive terminal is connected by an R wire to the engine 
compartment fusebox. The feed passes through fuse 16 and is connected to the contacts 
and coil of the horn relay. In this condition the horn relay receives a permanent feed from 
the battery.
Horns Operation
When one of the horn switches is pushed, an earth path is completed from the horn relay 
coil on a PO wire from the engine compartment fusebox, via header C0291 LHD/C0286 
RHD, the rotary coupler and horn switches, to earth via fixings E110.
The completed earth path energises the horn relay coil, closing the relay contacts. The feed 
from fuse 16 passes through the relay contacts to the LH and RH horns on PG wires causing 
the horns to sound.
The LH horn is connected to earth point C0564-1 on a B wire. The RH horn is connected to 
earth header C0018 on a B wire. 
						

							DESCRIPTION AND OPERATION
4.144DISCOVERY SERIES II
CLOCK
DESCRIPTION
General
The digital clock is located on the facia. The clock receives a permanent feed from the 
battery and is illuminated when the ignition switch is in position I or II.
OPERATION
Clock Supply
Circuit supply
A feed from the battery positive terminal is connected by an R wire to the engine 
compartment fusebox, where it passes to fusible links 3 and 8 and to fusible links 1 and 7, 
which are connected in series. The feed from fusible link 7 is connected to the contacts of 
the auxiliary circuits relay located in the engine compartment fusebox.
A permanent feed from fusible link 3 is connected to the passenger compartment fusebox 
by an NR wire, where it passes through fuse 20. From fuse 20 the feed is connected by a P 
wire, through header C0725 to the digital clock.
Ignition switch supply
When the ignition switch is in position I or II, the feed from fusible link 8 flows to the 
passenger compartment fusebox on an NW wire. From the fusebox the feed flows on an N 
wire to the ignition switch.
From the ignition switch the feed continues on an LGW wire to fuse 26 in the passenger 
compartment fusebox. From fuse 26 the feed is connected by an LG wire to the coil of the 
auxiliary circuits relay. The coil of the auxiliary circuits relay is now energised, and is 
connected by a B wire to earth header C0018, via header C0286 LHD/C0288 RHD.
Clock Operation
With the coil of the auxiliary circuits relay energised, the relay contacts close. This allows the 
feed from fusible links 1 and 7 to pass through the relay contacts to the passenger 
compartment fusebox on a WG wire.
The feed then passes through fuse 16 and is connected to the digital clock on an LGP wire. 
This feed provides the illumination when the ignition switch is in position I or II. The digital 
clock is connected, via headers C0725 and C0760 to earth header C0017 LHD/C0018 RHD 
on a B wire.
The permanent feed to the digital clock, via fusible link 3 in the engine compartment fusebox 
and fuse 20 in the passenger compartment fusebox ensure that the time settings are 
retained in the digital clock memory. 
						

							DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.145
CIGAR LIGHTER
DESCRIPTION
General
The cigar lighter is located in the centre console. The socket accepts a standardized plug 
type. The lighter is operated by depressing the centre of the lighter which latches the heated 
element into the holder.
OPERATION
Cigar Lighter Supply
Circuit supply
A feed from the battery positive terminal is connected by a R wire to the engine compartment 
fusebox, where it passes to fusible link 8 and fusible links 1 and 7 which are connected in 
series. The feed from fusible link 7 is connected to the auxiliary circuits relay mounted in the 
engine compartment fusebox.
The feed from fusible link 8 is connected to the passenger compartment fusebox on an NW 
wire and from the fusebox to the ignition switch on an N wire.
Ignition switch supply
When the ignition switch is in position I or II, the feed from fusible link 8 flows through the 
ignition switch) to the passenger compartment fusebox on an LGW wire. The feed continues 
through fuse 26 and is connected by an LG wire to the auxiliary circuits relay. The feed 
passes through the auxiliary relay coil and is connected to earth header C0018, via header 
C0285 LHD/C0288 RHD on a B wire.
The auxiliary circuits relay is energised which closes the relay contacts. This allows the feed 
from fusible link 7 to pass through the relay contacts to the passenger compartment fusebox 
on a WG wire. The feed then passes through fuse 15 and is connected, through header 
C0286 LHD/C0291 RHD to the cigar lighter on an LGW wire. The cigar lighter is connected 
through header C0286 LHD/C0288 RHD to earth header C0018 on a B wire. 
						

							DESCRIPTION AND OPERATION
4.146DISCOVERY SERIES II
Cigar Lighter Operation
With the ignition switch in position I or II the supply circuit is completed as the auxiliary relay 
is closed. Current is available at the cigar lighter.
When the cigar lighter is pushed into its holder, a central contact on the element completes 
the circuit and current flows through the element to earth on a B wire via header C0286 LHD/
C0288 RHD and earth header C0018.
Locking clips in the holder hold the cigar lighter in position in the housing. As the temperature 
of the element rises, heat is transmitted to the locking clips. The heat causes the locking 
clips to expand and release the cigar lighter from the housing at a predetermined 
temperature.
When the cigar lighter is released, the central contact on the element is disconnected, the 
power supply circuit is now broken and the lighter element starts to cool. 
						

							DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.147
ACCESSORY SOCKET
DESCRIPTION
General
The accessory socket is located behind the rear seats in the LH trim panel and is of similar 
construction to the cigar lighter socket. The socket has a maximum power rating of 180 
Watts and accepts a standardised plug type. The location of the accessory socket is 
illuminated when the side lights are switched on.
OPERATION
Accessory Socket Supply
Circuit supply
A feed from the battery positive terminal is connected by an R wire to the engine 
compartment fusebox, where it passes to fusible link 8 and to fusible link 7 via fusible link 1. 
The feed from fusible link 7 is connected to the auxiliary circuits relay mounted in the engine 
compartment fusebox.
The feed from fusible link 8 is connected to the passenger compartment fusebox on an NW 
wire and from the fusebox to the ignition switch on an N wire.
Ignition switch supply
When the ignition switch is in position I or II, the feed from fusible link 8 flows through the 
ignition switch to the passenger compartment fusebox on an LGW wire. The feed continues 
through fuse 26 in the passenger compartment fusebox and is connected by an LG wire to 
the auxiliary circuits relay. The feed passes through the relay coil and is connected to earth 
header C0018 on a B wire, via header C0286 LHD/C0288 RHD.
The auxiliary relay is energised which closes the relay contacts. This allows the feed from 
fusible link 7 to pass through the relay contacts and to the passenger compartment fusebox 
on a WG wire. The feed then passes through fuse 32 and is connected to the accessory 
socket on a PG wire. The accessory socket is connected to earth eyelet connector C0707 
by a B wire. 
						

							DESCRIPTION AND OPERATION
4.148DISCOVERY SERIES II
IN-CAR ENTERTAINMENT (ICE)
DESCRIPTION
General
The base and mid-line systems are contained within the same wiring diagram, the high-line 
system and the combined ICE/navigation system each have separate wiring diagrams. This 
section covers all three wiring diagrams.
Base and Mid-Line In-Car Entertainment Description
Base ICE description
The base in-car entertainment system consists of a head unit, located in the centre of the 
fascia, four 30 Watt speakers located in the doors and a single AM/FM aerial mounted on 
the RH rear side window.
Mid-line ICE description
The mid-line in-car entertainment system consists of a head unit, located in the centre of the 
fascia, four 30 Watt speakers located in the doors, a high range speaker located in each A 
post trim and a single AM/FM aerial mounted on the RH rear side window.
NOTE: A CD autochanger may be located under the RH front seat and is a dealer fit option.
The system can be controlled from the head unit or remote controls located on the LH side 
of the steering wheel.
In-Car Entertainment (ICE) Base and Mid line Supply
Circuit supply
A permanent feed from the battery positive terminal is connected by an R wire to the engine 
compartment fusebox, where it passes through fusible link 3. From fusible link 3 the feed 
passes on an NR to fuse 20 in the passenger compartment fusebox. From fuse 20 the feed 
flows on a P wire via header C0725 to the head unit. This feed supplies power to the internal 
memory and the power switch on the head unit.
A feed for illumination passes through fusible link 13 in the engine compartment fusebox and 
on an NG wire to the lighting switch. From the lighting switch the feed passes on an R wire 
to fuse 33 in the passenger compartment fusebox. The feed from fuse 33 is connected to 
header C0759 by an RO wire. From header C0759 the feed is connected on a RN wire to 
the head unit.
The permanent feed to the engine compartment fusebox also passes in series through 
fusible links 1 and 7. From fusible link 7 the feed is connected to the contacts of the auxiliary 
circuits relay. 
						

							DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.149
Ignition switch supply
When the ignition switch is in position II, the feed from fusible link 8 in the engine 
compartment fusebox flows to the passenger compartment fusebox on a NW wire.
From the passenger compartment fusebox the feed is connected to the ignition switch on an 
N wire. The feed from the ignition switch is connected to fuse 26 in the passenger 
compartment fusebox on an LGW wire.
From fuse 26 the feed is connected on an LG wire to the coil of the auxiliary circuits relay. 
The relay coil is earthed via header C0286 LHD/C0288 RHD to earth header C0018 on a B 
wire.
In-Car Entertainment Base and Mid-Line Operation
When the ignition switch is in position II the coil of the auxiliary relay is energised, with the 
coil energised the contacts of the auxiliary relay close.
The feed from the contacts of the auxiliary relay flows on a WG wire to fuse 16 in the 
passenger compartment fusebox. From fuse 16 a feed on an LGO wire flows to the aerial 
amplifier. The aerial amplifier is locally earthed to the vehicle. Another feed from fuse 16 is 
connected through splice joint A7 on a LGP wire to the head unit.
When the power switch on the head unit is turned on, the internal amplification and power 
supply circuits are energised from the fuse 16 supply. The head unit is earthed on a B wire 
to earth point C0361-1.
RH rear door speaker
The positive output from the head unit is connected on a BG wire to connector interface 
C0436-1/C0803-1. From the interface the positive output continues on a BU wire to the RH 
rear door speaker. The RH rear door speaker negative output is connected on a BG wire to 
connector interface C0436-2/C0803-2. From this interface the negative output is connected 
on a BU wire to the head unit.
RH front door speaker
The positive output from the head unit is connected on a BK wire to the RH front door 
speaker. The RH front door speaker negative output is connected on a BR wire to the head 
unit.
RH high range A post speaker (Mid-line model only)
From connector interface C0459-3/C0744-3 the positive output continues on a BK wire to 
connector interface C0485-14/C0480-14, and from the connector interface on a BK wire to 
the RH high range A post speaker. The RH high range A post speaker negative output is 
connected on a RB wire to connector interface C0485-13/C0480-13, then on a BR wire to 
connector interface C0459-4/C0744-4.