Range Rover P38
86
ELECTRICAL
NEW RANGE ROVER
20
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.
