Range Rover P38
86
ELECTRICAL
NEW RANGE ROVER
18
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.