Defender Electric Diagrams. Manual - part 18

CIRCUIT OPERATION

DEFENDER 90 NAS

INDICATORS / 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

DEFENDER 90 NAS

Right 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);

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Hazard warning switch tell tale, (C96-7) by brown/red wire.

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RH front direction indicator light (C2-1) by green/white wire.

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RH rear direction indicator light (C402-2) by green/white wire.

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Instrument pack RH indicator warning light (C230-9) by green/white wire.

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Trailer connector (C499-3) by green/white wire.

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LH front direction indicator light (C1-1) by green/red wire.

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LH rear direction indicator light (C403-2) by green/red wire.

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Instrument pack LH indicator warning light (C230-10) by green/red wire.

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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 NAS

INTERIOR 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 driver's door switch (C266-1) by the purple/green
wire, the passenger's 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

DEFENDER 90 NAS

INTERIOR 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

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;

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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.

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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.

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