Land Rover Defender Electrical Library 3rd Edition Nas Rover Manual

							CIRCUIT OPERATION
DEFENDER 90 NAS25With the column switch in the dip position, power from the column switch (C36-6) is fed
to fuses 7 and 8 of the passenger compartment fuse box (C580-13) on a blue/red wire.
With the column switch in the main beam position, power from the column switch (C36-
5) is fed to fuses 9 and 10 of the passenger compartment fuse box (C580-17) on a
blue/white wire via a header joint (C289).  A feed is also supplied through the header
joint (C289) to the instrument pack main beam warning light (C233-5) on a blue/white
wire and grounded on a black wire.  
Fuse 7 supplies the RH front dipped headlight (C11-2) on a blue/black wire. Fuse 8
supplies the LH front dipped headlight (C9-2) on a blue/pink wire. Fuse 9 supplies the
RH front main beam headlight (C11-1) on a blue/orange wire. Fuse 10 supplies LH front
main beam headlight (C9-1) on a blue/slate wire.  All lights are grounded on black
wires.  
Headlight flash  
A continuous feed from fusible link 1 through fuse 2 of the engine compartment fuse box
(C574-3) is supplied to the column switch (C36-7) on a purple wire.  When the headlight
flash switch is operated, power flows through the switch (C36-5) to fuse 9 and 10 of the
passenger compartment fuse box (C580-17) on a blue/white wire.  Power is also supplied
from the switch to the instrument pack main beam warning light (C233-5) on a blue/white
wire via a header joint (C289).  All lights are grounded on black wires.  
						

							CIRCUIT OPERATION
26DEFENDER 90 NASEXTERIOR LAMPS - Lights On Alarm   
DESCRIPTION  
If the side lights are switched on when the ignition is in the off position, opening either
the drivers door or passengers door will cause the lights on alarm to sound.  
OPERATION  
Feed from the positive battery terminal is connected to the engine compartment fuse box
(C632-1) by a brown wire.  Current passes through fusible link 1 and fusible link 5 of the
engine compartment fuse box which are connected in series. Fusible link 5 (C570-2) is
connected to  the ignition switch  (C28-1) by a brown wire.  
With the ignition switch in position II, power flows through the ignition switch (C94-1)
to fuse 1 of the passenger compartment fuse box (C580-1) on the white wire.  Fuse 1
(C580-2) supplies the multi-function ECU (C16-2) on the white/green wire.  If the ECU
receives a signal from the ignition switch, the lights on alarm will not sound.  
Fusible link 4 of the engine compartment fuse box (C573-2) is connected to the lighting
switch (C41-1) by the brown wire.  With the lighting switch on, power flows through the
switch (C41-2) to fuse 11 of the passenger compartment fuse box (C581-1) on the red
wire.  Fuse 11 (C581-2) is connected to the dimmer circuit (C285-7) on the red/black
wire and from the dimmer circuit (C285-15) to the lights on sounder, located in the ECU
(C16-4), on the red/white wire.  
Fuse 2 of the engine compartment fuse box (C574-3) supplies the ECU with a permanent
feed on the purple wire.  The ECU is connected to the drivers door switch (C266-1) by
the purple/green wire. The ECU is connected to the passengers door switch (C265-1) by
the purple/white wire. Opening either door closes a door switch, connecting the ECU to
ground.  Provided the ECU is receiving a lights on signal (C16-4) but no ignition signal
(C16-2), the lights on alarm ground is switched to a black wire (C16-6) and the alarm
sounds.  
						

							CIRCUIT OPERATION
DEFENDER 90 NAS27INDICATORS / HAZARD WARNING LIGHTS   
DESCRIPTION  
The indicators are controlled from the steering column switch and operate when the
ignition switch is in position II.  Moving the column switch for a left turn causes the left
hand indicator lights to flash.  Moving the column switch for a right turn causes the right
hand indicators to flash.  
The hazard light switch is located towards the center of the dash panel. Hazard operation
is not dependent on the position of the ignition switch.  When the hazard switch is
depressed, both left hand and right hand indicator lights flash.  
OPERATION  
Feed from the positive battery terminal is connected to the engine compartment fuse box
(C632-1) by the brown wire.  Power flows through fuse 5 of the engine compartment fuse
box (C575-3) and feeds the hazard warning switch (C96-2) on the purple wire. The
battery is also connected to  fusible link 1 and fusible link 5 of the engine compartment
fuse box which are connected in series. Fusible link 5 (C570-2) is connected to  the
ignition switch  (C28-1) by the brown wire.  
Indicators  
With the ignition switch in position II, power flows across the ignition switch (C94-1) to
fuse 17 of the passenger compartment fuse box  (C581-13) on the white wire.  Fuse 17 of
the passenger compartment fuse box (C581-14) is connected to the hazard warning switch
(C96-4) by the green wire.  With the hazard warning switch in the off position, power
flows through the hazard warning switch (C96-1) to the flasher unit (C547-85) on the
light green wire.  The flasher unit (C547-87) is connected to the column switch (C36-3)
by the light green/brown wire and grounded by a black wire.  
Left turn  
Moving the column switch to the left turn position allows power to flow through the
switch (C36-4) to  the trailer connector (C499-4), the LH rear direction indicator light
(C403-2), LH front direction indicator light (C1-1) and instrument pack LH indicator
warning light (C230-10) on green/red wires. The flasher unit (C547-30) is connected to
the instrument pack trailer warning light (C233-1) by the light green purple wire. All
lights are grounded on black wires.  With the circuit complete, the flasher unit
commences opening and closing the circuit, causing the LH indicator lights to flash. The
flasher unit connects power to the instrument pack trailer warning light during the first
flash cycle only, unless a trailer is connected.   
						

							CIRCUIT OPERATION
28DEFENDER 90 NASRight turn  
Moving the column switch to the right turn position allows power to flow through the
switch (C36-2) to  the trailer connector (C499-3), the RH rear direction indicator light
(C402-2), RH front direction indicator light (C2-1) and instrument pack RH indicator
warning light (C230-9) on green/white wires. The flasher unit (C547-30) is connected to
the instrument pack trailer warning light (C233-1) by the light green purple wire. All
lights are grounded on black wires.  With the circuit complete, the flasher unit
commences opening and closing the circuit, causing the RH indicator lights to flash. The
flasher unit connects power to the instrument pack trailer warning light during the first
flash cycle only, unless a trailer is connected.  
Hazards  
The hazard warning switch (C96-2) is supplied with a permanent feed from fuse 5 (C575-
3) of the engine compartment fuse box on the purple wire.  Pressing the switch to the on
position allows power to flow through the switch (C96-1) to the flasher unit (C547-85) on
the light green wire.  The flasher unit (C547-87) is connected to the following via the
hazard warning switch (C96-5);  
· Hazard warning switch tell tale, (C96-7) by brown/red wire. 
· RH front direction indicator light (C2-1) by green/white wire. 
· RH rear direction indicator light (C402-2) by green/white wire. 
· Instrument pack RH indicator warning light (C230-9) by green/white wire. 
· Trailer connector (C499-3) by green/white wire. 
· LH front direction indicator light (C1-1) by green/red wire. 
· LH rear direction indicator light (C403-2) by green/red wire. 
· Instrument pack LH indicator warning light (C230-10) by green/red wire. 
· Trailer connector (C499-4) by green/red wire. All lights are grounded on black
wires.  
With the flasher unit energized, the circuit is repeatedly open and closed, causing all
indicator lights to flash. If no trailer is connected to the vehicle,  the flasher unit supplies
power to the instrument pack trailer warning light on the light green/purple wire, during
the first flash cycle only, causing it to flash once.  
						

							CIRCUIT OPERATION
DEFENDER 90 NAS29INTERIOR LAMPS  
DESCRIPTION  
Two interior lamps are provided, one in the front and one in the rear of the vehicle.  The
front interior light can be switched on manually using its integral switch.  If either front
door is or tail door is opened, both lights are illuminated.  The lights are controlled by the
multi-function ECU.  The ECU contains a time out feature which switches off the interior
lights after a specified time period if either of the doors is left open, thus preventing
unnecessary battery drain.  
OPERATION  
Feed from the positive battery terminal is connected to the engine compartment fuse box
(C632-1) by the brown wire.  Current passes through fusible link 1 and fusible link 5 of
the engine compartment fuse box which are connected in series. Fusible link 5 (C570-2)
is connected to  the ignition switch  (C28-1) by the brown wire.  
With the ignition switch in position II, power flows across the switch (C94-1) to fuse 1
of the passenger compartment fuse box (C580-1) on the white wire.  Fuse 1 is connected
to the ECU (C16-2) by the white/green wire.  
Fuse 1 of the engine compartment fuse box (C574-4) is connected to the rear interior light
(C358-3) by the purple wire.  The rear interior light is grounded through the ECU (C62-1)
on the purple/blue wire.  
Fuse 2 of the engine compartment fuse box (C574-3) provides a permanent feed to the
ECU (C16-1) on the purple wire and feeds the front interior light (C356-1) on the purple
wire.  The front interior light is grounded through the ECU (C62-1) on the purple/blue
wire.  
The ECU (C62-5) is connected to the drivers door switch (C266-1) by the purple/green
wire, the passengers door switch (C265-1) and rear door switch (C615-1) by
purple/white wires.  When any door is opened, the door switch closes and a ground signal
is detected by the ECU.  The ECU switches the route to ground for the interior lights
(C62-1 to C62-6), illuminating the interior lights.  After a time period has elapsed with the
door switch ground route detected, the ECU switches off the ground route for the interior
lights.  
Switching the front interior light switch to the on position provides a route to ground
(C357-1) on the black wire and the bulb illuminates. In this condition, the time out feature
is overridden. 
						

							CIRCUIT OPERATION
30DEFENDER 90 NASINTERIOR ILLUMINATION  
DESCRIPTION  
The automatic gearbox selector is illuminated when the ignition switch is in position II.
When the side lights are switched on, the interior controls and gauges are illuminated so
that they can be easily located during night driving, the gearbox selector illumination is
dimmed to prevent dazzling.  Two levels of illumination, high and low, can be selected
using the dimmer switch.  
OPERATION  
Feed from the positive battery terminal is connected to the engine compartment fuse box
(C632-1) by the brown wire.  Current passes through fusible link 1 and fusible link 5 of
the engine compartment fuse box which are connected in series. Fusible link 5 (C570-2)
is connected to  the ignition switch  (C28-1) by the brown wire.  
With the ignition switch in position II, power flows through the ignition switch (C94-1)
to fuse 17 of the passenger compartment fuse box (C581-13) on the white wire.  Fuse 17
(C581-14) supplies the main relay (C951-87A) on the green wire.  When the relay is not
energized, power flows through the relay (C951-30) to the automatic gearbox selector
indicator light (C245-1) on the red/pink wire.  The gearbox selector indicator light is
grounded on a black wire.  
The lighting switch (C41-1) is supplied from fusible link 4 of the engine compartment
fuse box (C573-2) on the brown wire.  Moving the lighting switch to the sidelight position
allows power to flow through the switch (C41-2) to fuse 11 of the passenger compartment
fuse box (C581-1) on the red wire. Fuse 11 (C581-2) supplies the following components; 
· Dimmer circuit on the red/black wire. With the dimmer switch in the high position,
power flows through the header joint (C285-10) and dimmer switch (C201-3) on the
red/black wire. The dimmer switch (C201-2) is connected to the header joint (C285-
20) by the red/white wire.  With the dimmer switch in the low position, power
flows through the header joint (C285-9) to the in-line resistor (C425-1) on the
red/black wire.  The in-line resistor (C425-2) is connected to the header joint
(C285-19) by the red/white wire.  
· Illumination relay solenoid (C951-86) on the red/black wire.  The solenoid (C951-
85) is grounded on a black wire.  With the lighting relay energized, power from fuse
17 of the passenger compartment fuse box is diverted through the dimmer circuit
before flowing through the gearbox selector indicator light.    
						

							CIRCUIT OPERATION
DEFENDER 90 NASREV: 9/9731Power from the dimmer circuit flows through the following on red/white wires; 
· Left hand heater control illumination (C942-1). 
· Tachometer illumination (C936-1). 
· Speedometer illumination (C932-1). 
· Fuel gauge illumination (C935-1). 
· Right hand heater control illumination (C941-1). 
· Coolant temperature gauge illumination (C943-1). 
· Cigar lighter illumination (C74-1). 
· HRW switch illumination (C947-7). 
· Rear wiper switch illumination (C79-7). 
· Rear washer switch illumination (C73-8). 
· Clock illumination (C948-1). 
· Hazard warning switch illumination (C96-11). 
All illumination lamps are grounded on black wires.  
						

							CIRCUIT OPERATION
32DEFENDER 90 NASREV: 9/97INSTRUMENTS  
DESCRIPTION  
The vehicle relays information to the driver via the instrument pack. The instrument pack
contains lights and analogue gauges.  The color of the light  denotes the severity of the
information, warning lights are red, caution lights are orange, green and blue lights
indicate that a  system is operating.  
The analogue gauges relay information to the driver such as engine speed and engine
temperature.  
OPERATION  
Feed from the positive battery terminal is connected to the engine compartment fuse box
(C632-1) by the brown wire.  Current passes through fusible link 1 and fusible link 5 of
the engine compartment fuse box which are connected in series. Fusible link 5 (C570-2)
is connected to the ignition switch (C28-1) by the brown wire.  
With the ignition switch in position II, power flows through the switch (C94-1) to fuse 1
of the passenger compartment fuse box (C580-1) and to the in-line resistor (C38-1) on
white wires.  The in-line resistor (C37-2) is connected to the ground side of the
instrument pack ignition/no charge warning light (C230-5) by the yellow/brown wire.  
Fuse 1 of the passenger compartment fuse box is connected to the instrument pack (C230-
4) by the white/green wire via a header joint (C287) and feeds the following warning
lights; 
· Seat belt warning light - grounded (C230-1) on the white/black wire via the seat belt
buckle switch (C100-2).  Illuminates with the ignition in position II and seat belt
not fastened. 
· Differential warning light - grounded (C233-8) on the black/blue wire through the
differential lock unit (C306-1). Illuminates with the ignition in position II and
differential lock engaged. 
· Oil pressure warning light - grounded (C230-3) on the white/brown wire via a
header joint (C288) through the oil pressure switch (C187-1). Illuminates with the
ignition in position II and engine oil pressure below minimum.  
						

							CIRCUIT OPERATION
DEFENDER 90 NASREV: 9/9733· Brake/system warning light - grounded (C230-6) on the white/yellow wire, via a
header joint (C285), through the handbrake switch (C91-1) or brake fluid level
switch (C26-1). Illuminates with the ignition in position II and the handbrake
applied or when the brake fluid level drops below minimum. As a bulb check, in the
event of the handbrake not being applied, the lamp will illuminate for 3 seconds
after the ignition is first turned on. This function is served by the Warning Lamp
Check Unit which provides an alternative ground path for the lamp during the timed
period.
· Ignition/no charge warning light - grounded (C230-5) on the yellow/brown wire via
the diode (C116-1) and generator (C185-1) on the brown/yellow wire.  The
ignition/no charge warning light illuminates if the generator produces no output
voltage. See charging and starting.  Fuse 1 of the passenger compartment fuse box
feeds the following: 
· Instrument pack engine immobilization warning light (C233-3) on the white/green
wire.  The light is grounded (C233-10) on the red/slate wire through the engine
immobilization unit (C306-1).  Illuminates with the ignition in position II and
engine immobilized. 
· Instrument pack speedometer (C932-2) on the white/green wire.  The speedometer
is grounded (C932-3) on a black wire and receives a road speed signal (C932-1)
from the speed sensor (C195-3) on the black/red wire. 
· Instrument pack tachometer (C938-1) on the white/green wire.  The tachometer is
grounded (C937-1) on a black wire and receives the engine speed signal  (C937-1)
from the generator (C183-1) on the white/slate wire. 
· Instrument pack fuel gauge (C860-2) on the white/green wire.  The fuel gauge is
grounded (C860-1) on a black wire and receives the fuel level signal (C860-3) from
the fuel tank unit (C113-1) on the green/black wire. 
· Instrument pack coolant temperature gauge (C940-2) on the white/green wire.  The
coolant temperature gauge is grounded (C940-3) on a black wire and receives the
coolant temperature signal (C940-1) from the coolant temperature sensor (C113-1)
on the green/black wire.  
The instrument pack sidelights warning light is illuminated when the lighting switch is in
the sidelights or headlights position.  Fusible link 4 of the engine compartment fuse box
(C573-2) is connected to the lighting switch (C41-1) by the brown wire. 
						

							CIRCUIT OPERATION
34DEFENDER 90 NASREV: 9/97With the lighting switch in the on position, power flows across the switch (C41-2) to fuse
12 of the passenger compartment fuse box (C581-1) on the red wire.  Fuse 12 of the
passenger compartment fuse box supplies the instrument pack sidelights warning light
(C233-3) on the red/orange wire.  The warning light is grounded (C233-2) on a black
wire.
The instrument pack LH indicator warning light operates when the hazard warning switch
is operated or when the column switch is positioned for a left turn with the ignition switch
in position II.  With the hazard switch on, power is supplied from the hazard switch
(C96-6) to the LH indicator warning light (C230-10) via a header joint (C286) on the
green/red wire. The warning light is grounded (C233-2) on a black wire.  With the
ignition switch in position II and the column switch positioned for a left turn,  power is
supplied to the warning light (C230-10) from the column switch (C36-4) via a header
joint (C286) on the green/red wire.  
The instrument pack RH indicator warning light operates when the hazard warning switch
is operated or when the column switch is positioned for a right turn with the ignition
switch in position II.  With the hazard switch on, power is supplied from the hazard
switch (C96-3) to the RH indicator warning light (C230-9) via a header joint (C286) on
the green/white wire. The warning light is grounded (C233-2) on a black wire.  With the
ignition switch in position II and the column switch positioned for a right turn,  power is
supplied to the warning light (C230-9) from the column switch (C36-2) via a header joint
(C286) on the green/white wire.  
The instrument pack trailer warning light flashes once when the hazard warning switch is
operated or when the column switch is positioned for a left or right turn with the ignition
switch in position II.  Power is supplied to the trailer warning light (C233-1) from the
flasher unit (C547-30) on the red/slate wire. The trailer warning light is grounded (C233-
2) on a black wire.  
The instrument pack main beam warning light illuminates when headlight main beam is
selected from the column switch or headlight flash is operated.  With headlight main beam
selected or headlight flash operated, power from the column switch (C36-5) supplies the
main beam warning light (C233-5) on the blue/white wire.  The main beam warning light
is grounded (C233-2) on a black wire.  
The instrument pack heated rear window warning light illuminates when the engine is
running and the HRW switch is depressed momentarily to signal the multi-function ECU
to switch the heating element on (see Heated Rear Window). Power from the HRW relay
(C44-30) is supplied to the HRW warning light (C929-1) on the white/black wire.  The
warning light is grounded (C928-1) on a black wire.