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

							DESCRIPTION AND OPERATION
4.130DISCOVERY SERIES II
Ignition switch supply
With the ignition switch in position I or II, a feed is connected from the ignition switch to the 
passenger compartment fusebox on an LGW wire.
The feed passes through fuse 26 in the passenger compartment fusebox and is connected 
on an LG wire to the coil of the auxiliary circuits relay in the engine compartment fusebox. 
This energises the coil and closes the relay contacts. The coil is earthed on a B wire from 
the engine compartment fusebox to earth header C0018, via header C0286 LHD/C0288 
RHD.
With the ignition switch in position II, a feed is connected from the ignition switch to the 
passenger compartment fusebox on a Y wire. The feed passes through fuse 25 in the 
passenger compartment fusebox, through splices A37, A58 and is connected on a GY wire 
to the reverse lamp switch on vehicles with manual transmission or the automatic 
transmission starter inhibitor/reverse lamp switch on vehicles with automatic transmission.
Interior Lamps Operation
Vanity and rear view mirror
With the ignition switch in position I or II, the feed from fusible link 7 passes through the 
auxiliary circuits relay contacts and is connected on a WG wire to the passenger 
compartment fusebox where it passes through fuse 15. From fuse 15 the feed is connected 
on an LGW wire, via header C0286 LHD/C0291 RHD to the interior mirror.
The power supply from fuse 15 in the passenger compartment fusebox supplies power to 
the interior rear view mirror. The automatic dip function of the mirror can be selected on or 
off on the mirror. The mirror is connected on a B wire to earth header C0706.
When reverse is selected, the feed from fuse 25 in the passenger compartment fusebox 
passes through the reverse switch contacts and is connected, via header C0287 LHD/
C0294 RHD to the interior mirror on a GN wire. This supplies power to the interior mirror and 
changes it from its dipped to normal condition when applicable.
The interior lamps operate independent of the ignition switch position and can be operated 
manually or automatically when a door is opened. 
						

							DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.131
Interior lamps - Manual operation
The feed from fuse 20 in the passenger compartment fusebox is connected to the header 
C0289 LHD/C0294 RHD. From the header the feed is connected on a P wire to header 
C0723. Three feeds on P wires are connected from header C0723 to the front interior lamp, 
the rear interior lamp and the load space lamp.
On Korean vehicles only, two feeds on P wires are connected from header C0723 to the rear 
interior lamp and the loadspace lamp. The front interior lamp/infra-red sensor is also 
connected on a P wire from splice joint A2.
The earth path from the load space lamp is on a PU wire, through headers C0723 and 
C0285 LHD/C0294 RHD to the BCU pin C0663-9.
When the front interior lamp is in the manual (continuous) operation position, the earth path 
from the lamp is on a B wire to earth header C0706.
When the rear interior lamp is in the manual (continuous) operation position, the earth path 
from the lamp is on a B wire to earth header C0707.
Interior lamps - Automatic operation
The feed from fuse 20 in the passenger compartment fusebox is connected to the header 
C0289 LHD/C0294 RHD. From the header the feed is connected on a P wire to the ignition 
switch illumination bulb. The earth connection from the ignition switch illumination is 
connected on a PU wire to the BCU pin C0663-9, via header C0285 LHD/C0294 RHD.
On Korean vehicles only, two feeds on P wires are connected from header C0723 to the rear 
interior lamp and the laod space lamp. The front interior lamp/infra-red sensor is also 
connected on a P wire from splice joint A2.
With the interior lamps set for automatic operation, switches located in the front and rear 
door lock motors, complete an earth path from the BCU. The interior lamps receive a feed 
from fuse 20 in the passenger compartment fusebox, via headers C0289 LHD/C0294 RHD 
and C0723 on P wires.
The earth path for the LH or RH (drivers) door switch is from the BCU pin C0660-17 to the 
LH or RH front door lock motor on a PW wire, via header C0285. The earth is connected on 
a B wire from the LH or RH door switch to earth header C0017 LHD/C0018 RHD. 
						

							DESCRIPTION AND OPERATION
4.132DISCOVERY SERIES II
The earth paths for the LH or RH (passenger) door switch, tail door switch and LH and RH 
rear door switches is from the BCU pin C0660-4 to header C0291 LHD/C0285 RHD on a 
PLG wire.
From the header C0291 LHD/C0285 RHD a PLG wire is connected to connector interface 
C0464-1/C0733-1. From the connector interface the earth continues on a PW wire to the LH 
or RH (passenger) door switch. The earth is connected from the switch on a B wire to earth 
header C0018 LHD/C0017 RHD.
From the header C0291 LHD/C0285 RHD a PLG wire is connected to the tail door switch 
and the LH and RH rear door switches. The earth from the tail door switch is connected on 
a B wire to earth header C0706. The earth from the LH and RH rear door switches are 
connected on B wires to earth header C0552.
When a door is opened the BCU provides earth paths from the interior lamps, the load space 
lamp and the ignition switch illumination through the BCU. The earth path(s) from the 
lamp(s) is on PU wires, through header C0723 and C0285 LHD/C0294 RHD to the BCU pin 
C0663-9. 
						

							DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.133
INTERIOR ILLUMINATION
DESCRIPTION
General
The interior illumination provides background lighting for the instrument pack and control 
switch graphics. The interior illumination operates with the side lamps or headlamps, 
independent of the ignition switch position.
The radio, air temperature control (if fitted) and digital clock displays are illuminated 
permanently. When the side lamps are switched on the displays are dimmed.
The LH and RH rear window switches will not illuminate if the rear window lift isolation switch 
is operated to isolate the rear windows.
On NAS/JAPAN vehicles, an instrument illumination dimmer rheostat is provided to dim the 
instrument pack and switch graphic illuminations. The rotary dimmer control is located on 
the lower left corner of the instrument pack.
OPERATION
Interior Illumination Supply
A feed from the battery positive terminal is connected on an R wire to the engine 
compartment fusebox where it passes through fusible link 13.
The feed from fusible link 13 is connected on an NG wire to the lighting switch.
Interior Illumination Operation
When the lighting switch is moved to the side lamps or headlamps position, the feed passes 
through the switch contacts and is connected to the passenger compartment fusebox on an 
R wire. The feed passes through fuses 11 and 33 in the fusebox.
A feed from fuse 33 is connected on an RO wire to header C0759.
A feed from fuse 11 is connected on an RB wire to header C0288 LHD/C0286 RHD.
From header C0759, RN wires supply power to the interior illumination bulbs, with the 
exception of the glove box switch. The glove box switch is supplied on an RB wire to the 
switch and an R wire from the switch to the glove box lamp. 
						

							DESCRIPTION AND OPERATION
4.134DISCOVERY SERIES II
From header C0286, RB wires pass through headers C0295 and C0724 and supply power 
to the remaining interior illumination bulbs.
All of the bulbs are earthed by B wires, with the exception of the rear window LH and RH 
switches. These switches are connected to the window lift isolation switch on SG wires 
which is then connected to earth on a B wire.
NAS/Japan vehicles only
The instrument illumination dimmer rheostat receives a supply on an RO wire from header 
C0759. The rheostat supplies a reduced power feed on an RN wire to the header C0759. 
The rheostat is earthed on a B wire to earth header C0018, via header C0760. 
						

							DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.135
INSTRUMENTS
DESCRIPTION
General
Indications of vehicle and system status are relayed to the driver by the instruments and 
warning lamps contained within the instrument pack. The warning lamps fitted in the 
instrument pack are dependant on model/market variants and the engine/gearbox fitted.
NOTE: Some of the warning lamps are LED indicators that are powered at low voltages from 
the instrument pack internal circuits.
OPERATION
Instruments Supply
Circuit supply
A feed from the battery positive terminal is connected on an R wire to the engine 
compartment fusebox where it passes through fusible link 8 and fuses 10 and 13.
A permanent feed from fuse 13 is connected to the passenger compartment fusebox on a 
PN wire. The feed is connected from the passenger compartment fusebox to the instrument 
pack on a PO wire.
A feed from fusible link 8 is connected on an NW wire to the passenger compartment 
fusebox and from the fusebox to the ignition switch on an N wire.
Ignition switch supply
With the ignition switch in position II, the feed from fusible link 8 flows through the ignition 
switch to the passenger compartment fusebox on a Y wire, where it passes through fuses 
25, 27, and 35. Fuse 27 is connected on an LG wire to the instrument pack.
Fuse 35 is connected to the instrument pack on a G wire. Fuse 25 is connected to connector 
interface C1837/C1838 on a GY wire. The connector interface supplies a feed to the 
differential lock resistor on a KG wire.
Internal voltage supplies
Some of the warning lamps operate at very low voltages, the reduced voltages are controlled 
by the instrument pack. The instrument pack is earthed from pin C0230-17 and pin C0230-
18 to earth header C0551 on B wires. 
						

							DESCRIPTION AND OPERATION
4.136DISCOVERY SERIES II
Instruments Operation
Handbrake and low brake fluid level warning lamp
The handbrake and low brake fluid level warning lamps are connected to the instrument 
pack from pin C0230-10 on a KO wire to Header C0293 LHD/C0285 RHD. From header 
CO293 LHD/C0285 RHD a KO wire is connected to the handbrake switch, the handbrake 
switch is locally earthed.
A second connection from header C0293 LHD/C0285 RHD is connected to the brake fluid 
level switch on a KO wire. The brake fluid level switch is earthed on a B wire.
If either of the switches closes, an earth circuit via the closed switch contacts is completed 
and the handbrake/low fluid level warning lamp will be illuminated. Power for the warning 
lamp is internally connected to a supply from pin C0230-19. Pin C0239-19 is supplied power 
from the ignition feed from fuse 27 in the passenger compartment fusebox.
Oil pressure warning lamp
The oil pressure warning lamp is connected to the instrument pack from pin C0230-6 on a 
WN wire to the oil pressure warning switch, the oil pressure warning switch is locally earthed.
If the oil pressure switch closes, an earth circuit via the closed switch contacts is completed 
and the oil pressure warning lamp will be illuminated. Power for the warning lamp is 
internally connected to a power supply from pin C0230-19. Pin C0239-19 is supplied power 
from the ignition feed from fuse 27 in the passenger compartment fusebox.
Refer to the Workshop Manual engine for detailed description and operation of the oil 
pressure warning lamp.
Ignition and no charge warning lamp - V8
The ignition and no charge warning lamp in the instrument pack is connected from pin 
C0230-11 to the alternator on an NY wire.
Refer to the starting and charging section of this manual for a detailed description and 
operation of the ignition and no charge warning lamp.
Ignition and no charge warning lamp - Td5
The ignition and no charge warning lamp is connected from pin C0230-11 of the instrument 
pack via header C0294 LHD/C0287 RHD to the alternator on an NY wire.
Refer to the starting and charging section - Td5 of this manual for a detailed description and 
operation of the ignition and no charge warning lamp. 
						

							DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.137
SRS warning lamp
The SRS warning lamp is connected from pin C0233-7 to pin C0256-13 on the SRS DCU 
on a YR wire.
Refer to Supplementary Restraint System (SRS) section of this manual for a description and 
operation of the SRS warning lamp circuit.
Fuel filter water warning lamp (Td5 models only)
A water sensor is installed in the fuel system, the power supply for the sensor is from fuse 
10 in the engine compartment fusebox and the closed contacts of the fuel pump relay on a 
WP wire. The operation of the fuel pump relay coil is controlled by the Engine Control 
Module (ECM). The coil of the fuel pump relay is connected to pin C0658-5 of the ECM on 
a UP wire. The water sensor is grounded on a B wire via splice joint A3 to earth eyelet 
C0810-1.
The water sensor measures the resistance of the liquid between two electrodes. The sensor 
outputs a voltage to the instrument pack pin C0233-11. The instrument pack monitors the 
voltage. When the water in the filter becomes too great, the instrument pack illuminates the 
warning lamp when the voltage reaches a predetermined level.
Engine management warning lamp - V8
The engine management warning lamp is connected from pin C0233-13 on the instrument 
pack to pin C0237-20 on the ECM on an RS wire.
Refer to the Workshop Manual - Engine Management System V8 for Description and 
Operation of the engine management warning lamp.
Engine management warning lamp - Td5
The engine management warning lamp is connected from pin C0233-13 on the instrument 
pack to pin C0658-6 on the ECM on an RS wire.
Refer to the Workshop Manual - Engine Management System Td5 for Description and 
Operation of the engine management warning lamp.
Glow plug warning lamp (Td5 vehicles only)
The glow plug warning lamp is connected from pin C0233-12 on the instrument pack to pin 
C0658-30 of the ECM on an BY wire.
Refer to the Workshop Manual Engine Management System Td5 for Description and 
Operation of the glow plug warning lamp. 
						

							DESCRIPTION AND OPERATION
4.138DISCOVERY SERIES II
Off road warning lamp
The off road warning lamp is connected from pin C0230-9 on the instrument pack to the off 
road mode switch.
Refer to the Self Levelling and Anti-Lock Braking System (SLABS) section in this manual for 
a description of the operation of the off road warning lamp.
SLS warning lamp
The SLS warning lamp is connected from pin C0233-2 on the instrument pack to the SLABS 
ECU pin C0655-8 on a WO wire.
Refer to the Self Levelling and Anti-Lock Braking System (SLABS) section of this manual for 
a description of the operation of the warning lamp circuit.
ABS warning lamp
The ABS warning lamp is connected from pin C0233-3 on the instrument pack to the SLABS 
ECU pin C0504-18 on a WR wire.
Refer to the Self Levelling and Anti-Lock Braking System (SLABS) section of this manual for 
a description of the operation of the warning lamp circuit.
Traction control warning lamp
The traction control warning lamp is connected from pin C0233-4 on the instrument pack to 
the SLABS ECU pin C0504-13 on a WU wire.
Refer to the Self Levelling and Anti-Lock Braking System (SLABS) section of this manual for 
a description of the operation of the warning lamp circuit.
Hill descent control active warning lamp (green)
The HDC active warning lamp is connected from pin C0233-5 on the instrument pack to the 
SLABS ECU pin C0504-16 on a WY wire.
Refer to the Self Levelling and Anti-Lock Braking System (SLABS) section of this manual for 
a description of the operation of the warning lamp circuit.
Hill descent fail warning lamp (amber)
The hill descent fail warning lamp is connected from pin C0233-10 on the instrument pack 
to the SLABS ECU pin C0504-17 on a WK wire.
Refer to the Self Levelling and Anti-Lock Braking System (SLABS) section of this manual for 
a description of the operation of the warning lamp circuit. 
						

							DESCRIPTION AND OPERATION
DISCOVERY SERIES II 4.139
Direction indicator warning lamps
The direction indicator left and right warning lamps are connected from the instrument pack 
pin C0233-16 via header C0293 LHD/ C0292 RHD to pin C0661-1 on the BCU. This 
connection is part of the serial data bus between the instrument pack and the BCU.
The BCU and the Intelligent Driver Module (IDM) control the operation of the direction 
indicators warning lamps.
Refer to the direction indicators and hazard warning lamps section of this manual for details 
of operation.
Trailer warning lamp
The trailer warning lamp is connected from the instrument pack pin C0233-16 via header 
C0293 LHD/ C0292 RHD to pin C0661-1 on the BCU on an SK wire. This connection is part 
of the serial data bus between the instrument pack and the BCU.
The BCU and the Intelligent Driver Module (IDM) control the operation of the trailer warning 
lamp.
Refer to the direction indicators and hazard warning lamps section of this manual for details 
of operation.
Seat belt warning lamp (if fitted)
The seat belt 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. The seat belt switch is connected 
to pin C0662-16 of the BCU on a RW wire. The seat belt switch is earthed on a B wire to 
earth header C0708 LHD/C0552 RHD.
The BCU controls the operation of the seat belt on warning lamp and an audible warning. 
The warning operates for a maximum of 6 seconds, after this time the BCU logic stops the 
warning output to the serial data bus.
The seat belt warning lamp is connected to the ignition supply from fuse 13 in the engine 
compartment fusebox. When the seat belt is fastened the seat belt switch is closed, and an 
earth path is completed from pin C0662-16 of the BCU on a RW wire to the closed contacts 
of the seat belt switch, to earth header C0708 LHD/C0552 RHD on a B wire.
When the earth path is completed the BCU logic circuits cancel the seat belt light on and 
seat belt audible warning signals sent via the serial data bus.