Defender Electric Diagrams. Manual - part 16

CIRCUIT OPERATION

DEFENDER 90 NAS

WIPERS AND WASHERS

DESCRIPTION

The front windscreen wipers are controlled from the column switch and operate when the
ignition switch is in position 'II'. The wipers have 2 speed settings, along with 2 flick
wipe speeds and a single wipe facility. An intermittent wipe function and programmed
wash wipe facility is controlled by the multi-function ECU.

Moving the wiper switch down from the off position initiates the intermittent wipe
function. Moving the wiper switch up one position from the off position, operates the
wipers at slow speed. Moving the wiper switch up 2 positions from the off position,
operates the wipers at fast speed. Pushing the wiper switch up from the off position,
against spring pressure, and releasing the switch causes the wipers to perform a single
wipe cycle at slow speed. Pressing the end of the wiper switch initiates the programmed
wash wipe sequence, windscreen washers operate while the switch is pressed and the
wipers continue to operate for a number of cycles after the switch is released.

The rear windscreen wiper and rear wash facilities are controlled from two switches
mounted to the dash panel.

Pressing the wiper switch causes the rear wiper to operate until the switch is turned off.
Pressing the washer switch causes the rear washer to operate until the switch is released,
the rear wiper also performs a number of cycles.

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 (C580-1), fuse 17 and fuse
18 (C581-13) of the passenger compartment fuse box on white wires. Fuse 17 supplies
the rear wash/wiper circuit, fuse 1 and fuse 18 supply the front wash/wiper circuit.

Front wipers and washers

Fuse 2 of the engine compartment fuse box (C574-3) provides a permanent 12 volt feed
to the ECU (C16-1) on the purple wire. Fuse 1 of the passenger compartment fuse box
(C580-2) supplies the ECU (C16-2) with a 12 volt feed on the white/green wire when the
ignition switch is in position 'II'.

CIRCUIT OPERATION

DEFENDER 90 NAS

Slow and fast speeds

Fuse 18 of the passenger compartment fuse box (C581-16) is connected to the wash/wipe
switch (C278-6) via a header joint (C289) by the green wire. Moving the switch to the
slow speed position allows power to flow across the switch (C278-1) to the wiper motor
(C30-3) on the blue/light green wire. The wiper motor is grounded (C30-1) on the black
wire and the wipers operate at slow speed. Moving the wiper switch to the fast position
allows power to flow through the switch (C278-5) to the wiper motor (C30-5) on the
red/light green wire. The wiper motor is grounded (C30-1) on the black wire and the
wipers operate at fast speed.

Park circuit

Positioning the wiper switch to the off position cuts power to the wiper motor on the
blue/light green or red/light green wire. The park circuit operates to return the wipers to
their park position. The park switch (C30-4), integral to the wiper motor unit, receives a
12 volt supply from fuse 18 of the passenger compartment fuse box (C581-16) via a
header joint (C289) on the green wire. The park switch is closed with the wipers in any
position other than their park position. With the park switch closed, power flows through
the switch (C30-2) to the front wiper relay (C39-5) on the brown/light green wire. The
front wiper relay (C39-2) is connected to the wiper switch (C278-4) by the yellow/light
green wire. Power flows through the wiper switch (C278-1) to the wiper motor (C30-3)
on the blue/light green wire. The wiper motor is grounded on the black wire. The wipers
operate until their park position is reached and the park switch opens, cutting power
supply to the wiper motor.

Intermittent wiper function

Moving the wiper switch to the intermittent wipe position allows power to flow across the
switch (C278-3) to the ECU (C62-9) on the light green/green wire. With a 12 volt signal
applied to the ECU from the wiper switch, the ECU switches the route to ground (C62-
22) for the front wiper relay winding (C39-4) on and off approximately every 6 seconds,
on the brown/slate wire. The front wiper relay (C39-8) and winding (C39-6) are powered
from fuse 18 of the passenger compartment fuse box (C581-16) via a header joint (C289)
on green wires.

With the front wiper relay energized, power flows across the relay (C39-2) to the wiper
switch (C278-4) on the yellow/light green wire. Power flows through the wiper switch
(C278-1) to the wiper motor (C30-3) on the blue/light green wire. The wiper motor is
grounded (C30-1) on the black wire and operates at slow speed. After approximately 1
second, the ECU de-energizes the front wiper relay and the wipers continue operating

CIRCUIT OPERATION

DEFENDER 90 NAS

through the park circuit until their park position is reached. Approximately 5 seconds
later, the ECU energizes the front wiper relay for 1 second. The process repeats until
power to the ECU from the wiper switch is broken by positioning the wiper switch to the
off position or slow speed wipe position.

Programmed wash/wipe function

Depressing the end of the wiper switch operates the programmed wash/wipe function.
The washer switch (C278-6) is supplied from fuse 18 of the passenger compartment fuse
box (C581-16), via a header joint (C289), on the green wire. When the switch is closed,
power flows through the switch (C278-2) to the windscreen washer pump (C8-2) and
ECU (C62-13), via a header joint (C288), on light green/black wires. The washer pump
(C8-1) is grounded on the black wire and operates until the washer switch is released.
With a 12 volt supply applied to the ECU from the washer switch, the ECU energizes the
front wiper relay by grounding the relay winding (C39-4) on the brown/slate wire. With
the front wiper relay energized, power flows across the relay (C39-2) to the wiper switch
(C278-4) on the yellow/light green wire. Power flows through the wiper switch (C278-1)
to the wiper motor (C30-3) on the blue/light green wire. The wiper motor is grounded
(C30-1) on the black wire and operates at slow speed. When power to the ECU (C62-13)
is cut, by releasing the washer switch, the ECU continues to energize the front wiper
relay for a time to allow approximately 2 further cycles of the front wipers. After the
front wiper relay has been de-energized, the park circuit returns the wipers to their park
position.

Rear wiper

Fuse 17 of the passenger compartment fuse box (C581-14) feeds the rear wiper switch
(C79-5) on the green wire. Closing the rear wiper switch allows power to flow through
the switch (C79-2) to the ECU (C62-15) on the red/light green wire. With a 12 volt feed
from the switch to the ECU, the ECU (C62-23) switches the route to ground from the rear
wiper relay winding (C124-86) on the brown/purple wire. The rear wiper relay (C124-
87) and winding (C124-85) are supplied from fuse 17 of the passenger compartment
fuse box (C581-14) on green wires. With the rear wiper relay energized, power flows
through the relay (C124-30) to the rear wiper motor (C835-1) on the brown/light green
wire. The rear wiper motor is grounded (C388-1) on the black wire. When power from
the rear wiper switch to the ECU is cut, the rear wipe park circuit operates to return the
wiper to the park position. When the rear wiper is in any position other than the park
position, the park switch (C835-2), integral to the motor, receives a 12 volt supply from
fuse 17 of the passenger compartment fuse box on the green wire. Power flows through
the park switch and wiper motor to ground on the black wire. When the wiper reaches its
park position, the park switch opens and power to the wiper motor is cut.

CIRCUIT OPERATION

DEFENDER 90 NAS

Rear wash

The rear wash switch (C73-5) is supplied from fuse 17 of the passenger compartment fuse
box (C581-14) on the green wire. Depressing the wash switch allows power to flow
through the switch (C73-2) to the rear washer pump (C21-2) and ECU (C62-16) on
black/light green wires. The washer pump (C21-1) is grounded on the black wire and
operates until the switch is released. When the ECU receives a 12 volt signal from the
washer switch, the ECU energizes the rear wiper relay by grounding the relay winding
(C124-86) on the brown/purple wire. The rear wiper relay (C124-87) and winding
(C124-85) are supplied from fuse 17 of the passenger compartment fuse box (C581-14)
on green wires. With the rear wiper relay energized, power flows through the relay
(C124-30) to the rear wiper motor (C835-1) on the brown/light green wire. The rear
wiper motor is grounded (C388-1) on the black wire. Releasing the rear washer switch
cuts the power supply to the ECU, however the ECU continues to provide a route to
ground for the rear wiper relay for a time to allow the rear wiper to complete
approximately 3 further wipe cycles. When the ECU de-energizes the rear wiper relay,
the rear wiper park circuit operates to return the rear wiper to the park position.

Content .. 14 15 16 17 ..