Range Rover. Manual - part 309

ELECTRICAL

DESCRIPTION AND OPERATION

Hazard Warning Lamps

The hazard warning lamps are operated from a
latching pushbutton switch located on the fascia and
can be activated at all times irrespective of the ignition
switch state. The switch has a tell-tale lamp to inform
the driver that the hazard warning lamps are
operational. The direction indicator warning lamps in
the instrument pack both flash together and the
instrument pack emits an audible ’tick’ in time with the
pulsed operation of the lamps. In the event of the
inertia switch being tripped, the BeCM will
automatically activate the hazard warning lamps.

Fog, Brake and Reversing Lamps

The fog, brake and reverse lamps are controlled by
switches which, when operated, complete an earth
path to the BeCM. The BeCM interprets the earth path
completion as a request for fog, brake or reverse lamp
operation and provides power outputs to the
applicable circuits to operate the lamps as requested.

The BeCM outputs are driven by Field Effect
Transistors (FET). The FET’s detect the continuity of
the applicable circuit. In the event of a bulb failure,
with the exception of the high mounted brake lamp,
the break in continuity is sensed by the BeCM which
generates the applicable ’BULB FAILURE’ message
in the message centre specifying the bulb or circuit
which has failed.

Fog Lamps

Front fog lamps

The front fog lamps are operated from a non-latching
switch on the fascia. The switch has a tell-tale lamp to
indicate that front fog lamps are active. When the
switch is operated it completes a momentary earth
path to the BeCM. The BeCM interprets the earth as a
request for front fog lamp operation and provides
power outputs to the LH and RH front fog lamps. If the
ignition is off or the side lamps or headlamps are off,
the request will not be granted and the tell-tale lamp
will not be illuminated.

With the ignition in position II and the side lamps or
headlamps are switched on, the BeCM will grant the
request and provide power to the fog lamps and the
tell-tale lamp. A second operation of the switch will
signal the BeCM to terminate fog lamp operation.

Also if the ignition or the side lamps or headlamps are
switched off, the output to the fog lamps is removed.
The fog lamps will be inactive when the ignition and
the side lamps or headlamps are next switched on.

On NAS vehicles, the front fog lamps will only operate
with the ignition in position II and headlamps switched
on. They will not operate with only the side lamps on.

Rear fog lamps

The rear fog lamps are operated from a non-latching
switch on the fascia. The switch has a tell-tale lamp to
indicate that the rear fog lamps are active. The rear
fog lamps operate in the same way as described for
the front fog lamps, with the exception that the rear
fog lamps will not operate unless the front fog lamps
are on. Switching off the front fog lamps will also
extinguish the rear fog lamps.

Brake Lamps

The brake lamps are operated from a plunger type
microswitch which is activated by the brake pedal.
The switch is a self adjusting microswitch with two
interlinked contacts, one normally open and the
normally closed.

When the brake pedal is depressed, the normally
open contacts close, supplying a 12 V signal to the
BeCM, cruise control ECU and the ABS ECU.
Simultaneously, the normally closed contacts open,
interrupting a 12 V supply to the ABS ECU.

The BeCM interprets the 12 V supply from the switch
as a request for brake lamp operation and provides
power outputs to the brake lamp circuits. When the
brake pedal is released the 12 V supply to the BeCM
is terminated and the BeCM deactivates the power
output to the brake lamp circuits.

Reversing Lamps

Manual transmission

The reverse lamps are operated by a plunger type
microswitch which is activated by a mechanical
linkage within the gearbox. When reverse gear is
selected with the ignition in position II, the microswitch
plunger is depressed completing an earth path to the
BeCM.

ELECTRICAL

NEW RANGE ROVER

DESCRIPTION AND OPERATION

The BeCM interprets the earth path as a request for
reverse lamp operation and provides power outputs to
the LH and RH reverse lamp circuits. When reverse
gear is deselected, the earth path to the BeCM is
terminated and the BeCM deactivates the power
output to the reverse lamp circuits.

Automatic transmission

The reverse lamps are operated by a signal generated
from the gearbox selector position switch located on
the side of the gearbox. The BeCM determines the
gear position from three microswitches (X, Y, Z) in the
selector position switch.

When the BeCM sees the correct output from the
position switch and the ignition is in position II, it
activates the power outputs to the reverse lamp
circuits. When reverse gear is deselected, the signal
from the position switch changes and the BeCM
deactivates the power output to the reverse lamp
circuits.

See AUTOMATIC GEARBOX, Description

and operation.

Trailer Lamps

The BeCM is programmed to accomodate additional
lighting loads when a trailer is being towed. The trailer
lamps have the same functionality as described
previously for rear fog lamps, reversing lamps,
parking/side lamps, direction indicators and hazard
warning lamps.

If the trailer lamps are of too high a Wattage, the
BeCM may interpret the loads as a short circuit to
ground and deactivate the power outputs to the trailer
and vehicle lighting circuits.

Wash Wipe System

Washer Fluid Level

The washer fluid reservoir has three motors for front,
rear and headlamp washer operation. The reservoir is
located in the right hand side of the engine
compartment below the battery. Each motor is
operated by the BeCM.

A level switch, operated by a float, is located in the
washer fluid reservoir. When the washer fluid is at a
sufficient level, the switch is closed and an earth path
to the BeCM is complete. When the washer fluid falls
to a level to open the switch, the BeCM monitors the
switch condition.

If the switch is open for longer than 5 seconds, the
BeCM generates a ’LOW SCREEN WASH’ message
in the message centre and disables the headlamp
wash/wipe function to preserve fluid. The message is
removed when the BecM senses that the switch is
closed and the ignition is off.

Front Wipers

Two front wipers are operated by a linkage assembly
and an electric motor located under the plenum grill
below the windscreen. The linkage and motor are
handed for left and right hand drive vehicles.

The front wiper motor has two speeds of operation;
slow and fast. The dc motor contains two permanent
magnets, three brushes and a park switch. The park
switch signals the BeCM that the wipers are in the
park position. When the wiper motor operates the park
switch closes, creating an earth path to the BeCM.
When the wipers reach the park position the park
switch opens, breaking the earth path to the BeCM.
The BeCM will then stop the wipers at this position if
requested.

If the park switch fails, the BeCM cannot monitor the
wiper position on the screen. To protect the motor
from damage, the BeCM will allow wiper operation but
will stop the wiper motor at a random position when
the wiper switch is moved to the off position.

The BeCM controls all front wiper functions, with the
wiper motor being supplied power via relays 1 and 8
in the engine compartment fusebox. The front wipers
and washers will only operate with the ignition in
position I or II. If the ignition is moved to position 0
(off) when the wipers are operating, the wipers will
continue to operate until they reach the park position.

To maximise battery voltage during engine cranking,
most BeCM controlled functions are inhibited. During
cranking, the BeCM will suspend wiper operation until
cranking has finished and then reinstate wiper
operation.

ELECTRICAL

DESCRIPTION AND OPERATION

All front wiper functions are controlled from a stalk
switch located on the right hand side of the steering
column. The front wiper functions, with the exception
of the programmed wash wipe function, are operated
by a combination of three switches. The following
table details the switch combinations for each
function.

Function

Switch

Flick wipe

Closed

Open

Off

Open

Intermittent

Open

Closed

Open

Slow

Open

Closed

Fast

Open

Closed

Flick wipe

The flick wipe function is operated by pushing the
stalk vertically upwards and releasing to perform one
cycle of the front wipers. Holding the stalk in this
position will operate the wipers for as long as the
switch is held.

When the three switches are in a combination for flick
wipe operation, the BeCM output to relay 1 is earthed,
energising the relay coil. With the relay energised, a
feed from fuse 25 in the engine compartment fusebox
is supplied, via the contacts of relay 8, to the slow
speed brushes in the wiper motor. When the wiper
motor moves from the park position, the contacts of
the park switch open.

When the switch is released, the BeCM continues to
energise the coil of relay 1 to allow the wipers to move
to the park position. When the motor reaches the park
position, the park switch closes completing an earth
path to the BeCM. The BeCM senses the completed
earth path and removes the earth for the relay 1 coil,
replacing it with a 12 V output. The relay 1 coil is
de-energised and the relay contacts open, removing
the feed to the motor and stopping the wipers.

Intermittent wipe

The intermittent function is operated by pushing the
switch one position vertically downwards to the first
position. The intermittent delay can be adjusted by
rotating the thumb wheel on the top of the stalk to the
left or right to reduce or increase the delay period.

When the three switches are in a combination for
intermittent operation, the BeCM output to relay 1 is
earthed, energising the relay coil. With the relay
energised, a feed from fuse 25 in the engine
compartment fusebox is supplied, via the contacts of
relay 8, to the slow speed brushes in the wiper motor.
When the wiper motor moves from the park position,
the contacts of the park switch open.

When the wiper motor reaches the park position, the
park switch closes completing an earth path to the
BeCM. The BeCM senses the completed earth path
and removes the earth for the relay 1 coil, replacing it
with a 12 V output. The relay 1 coil is de-energised
and the relay contacts open, removing the feed to the
motor and stopping the wipers.

The BeCM then initiates a delay by passing a voltage
to the delay potentiometer and measuring the
resistance through the potentiometer. The resistances
sensed by the BeCM and the associated delays are
listed in the following table.

Delay (Seconds)

Resistance (Ohms)

1.9K

4.7K

9.2K

17.4K

53K

When the delay has elapsed, the BeCM will operate
the wipers for one more cycle and then reinstate the
delay period. This will continue until the intermittent
function is deselected.

ELECTRICAL

NEW RANGE ROVER

DESCRIPTION AND OPERATION

When the intermittent function is switched off, if the
wipers are midway through a cycle, the BeCM
continues to energise the coil of relay 1 to allow the
wipers to move to the park position. When the motor
reaches the park position, the park switch closes
completing an earth path to the BeCM. The BeCM
senses the completed earth path and removes the
earth for the relay 1 coil, replacing it with a 12 V
output. The relay 1 coil is de-energised and the relay
contacts open, removing the feed to the motor and
stopping the wipers. If the wipers are not operating
when the intermittent function is deselected, then no
further wiper operation will take place.

Slow speed

The slow wipe function is operated by pushing the
stalk two positions vertically downwards.

When the three switches are in a combination for slow
wipe operation, the BeCM output to relay 1 is earthed,
energising the relay coil. With the relay energised, a
feed from fuse 25 in the engine compartment fusebox
is supplied, via the contacts of relay 8, to the slow
speed brushes in the wiper motor. When the wiper
motor moves from the park position, the contacts of
the park switch open.

When the switch moved to the off position, the BeCM
continues to energise the coil of relay 1 to allow the
wipers to move to the park position. When the motor
reaches the park position, the park switch closes
completing an earth path to the BeCM. The BeCM
senses the completed earth path and removes the
earth for the relay 1 coil, replacing it with a 12 V
output. The relay 1 coil is de-energised and the relay
contacts open, removing the feed to the motor and
stopping the wipers.

Fast speed

The fast wipe function is operated by pushing the stalk
three positions vertically downwards.

When the three switches are in a combination for fast
wipe operation, the BeCM output to relays 1 and 8 are
earthed, energising the relay coils. With the relay
energised, a feed from fuse 25 in the engine
compartment fusebox is supplied, via the contacts of
relay 8, to the fast speed brushes in the wiper motor.
When the wiper motor moves from the park position,
the contacts of the park switch open.

When the switch moved to the off position, the BeCM
continues to energise the coils of relays 1 and 8 to
allow the wipers to move to the park position. When
the motor reaches the park position, the park switch
closes completing an earth path to the BeCM. The
BeCM senses the completed earth path and removes
the earths for the coils of relays 1 and 8, replacing
them with a 12 V output. The relay 1 coil is
de-energised and the relay contacts open, removing
the feed to the motor and stopping the wipers.

Programmed wash/wipe

Programmed wash/wipe is selected by pressing the
lower button on the end of the wiper stalk. The washer
will continue to operate for as long as the button is
pressed.

When the switch is pressed an earth path is
completed to the BeCM. The BeCM interprets the
earth path as a request for programmed wash/wipe
and provides a 12 V output to the windscreen washer
pump. The output is supplied for 1.5 seconds or for as
long as the switch is held.

The BeCM changes the output to relay 1 to an earth
0.5 seconds after the switch is pressed, energising the
relay coil. With the relay energised, a feed from fuse
25 in the engine compartment fusebox is supplied, via
the contacts of relay 8, to the slow speed brushes in
the wiper motor. When the wiper motor moves from
the park position, the contacts of the park switch
open.

The BeCM operates the wipers for three complete
cycles and then continues to energise the coil of relay
1 to allow the wipers to move to the park position.
When the motor reaches the park position, the park
switch closes completing an earth path to the BeCM.

The BeCM senses the completed earth path and
removes the earth for the relay 1 coil, replacing it with
a 12 V output. The relay 1 coil is de-energised and the
relay contacts open, removing the feed to the motor
and stopping the wipers.

If the BeCM receives a washer fluid low signal in the
form of a completed earth path through the fluid level
sensor, programmed wash/wipe is restricted to only
operate the washer pump and the wipers for as long
as the switch is held.

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