Range Rover P38
86
ELECTRICAL
NEW RANGE ROVER
22
DESCRIPTION AND OPERATION
If no front wiper function is selected, the BeCM then
initiates a delay by passing a voltage to the delay
potentiometer and measuring the resistance through
the potentiometer. The delay is twice that of the front
intermittent delay. The resistances sensed by the
BeCM and the associated delays are listed in the
following table.
Delay (Seconds)
Resistance (Ohms)
4
1.9K
8
4.7K
16
9.2K
32
17.4K
64
53K
The BeCM will provide a 12 V output to the motor until
the park switch opens. The BeCM initiates the delay
by passing a voltage to the delay potentiometer and
measuring the resistance through the potentiometer.
The resistance is sensed by the BeCM which initiates
the appropriate delay period before supplying the
output to the motor for the next wiper operation.
If the front wiper is selected in the intermittent mode,
the BeCM will provide a 12 V output to the rear wiper
motor at the same time as it provides the earth path
for relay 1 to operate the front wipers. This
synchronises the front and rear wiper cycles at the
same time. The rear wiper operates on every alternate
operation of the front wipers until the front or rear
wiper functions are deselected.
If the front wipers are operating in the slow or fast
mode, the rear wiper will operate intermittently as
detailed above.
Reverse gear wipe
If reverse gear is selected with a front wiper function
active, the BeCM will operate the rear wiper as
detailed in the following table.
Front Wiper
Rear Wiper
Intermittent
Intermittent
Slow
Continuous
Fast
Continuous
The BeCM controls the reverse wipe operation when
an input from a gearbox reverse switch is sensed. The
intermittent operation is as detailed previously. When
reverse gear is deselected, the BeCM operates the
rear wiper motor until one full cycle is complete.
Programmed wash/wipe
Programmed wash/wipe is selected by pressing the
upper button on the end of the wiper stalk. The
washer will continue to operate for as long as the
switch 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 rear screen washer
pump. The output is supplied for 1.5 seconds or for as
long as the switch is held.
The BeCM provides a 12 V output to the rear wiper
motor 0.5 seconds after the pump starts. The BeCM
operates the wiper motor for three complete cycles
until it senses that the park switch is open and
removes the 12 V output to the motor, stopping the
wiper in the park position.
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 and the wiper for as long as the
switch is held.
Power Seats
The power seats are only available on the driver and
passenger front seats. The seats can be operated
when either front door is open and/or the ignition is in
position I or II. The power seats are each operated by
axis and lumbar control switches located on the side
of each seat trim panel.
The seat heater function is controlled by switches on
the HEVAC ECU control panel. Each switch when
pressed, completes an earth path which is sensed by
the BeCM as a seat heater request and activates the
appropriate seat heater. The seat heaters only
operate with the ignition in position II and the engine
running.
