Headlamp Wipers and Washers: Operation and Description
WIPERS AND WASHERS
84-20
DESCRIPTION AND OPERATION
Wiper Motor Blocking Protection
The wiper park signal is also used by the BCU for blocking protection of the front wiper motor. This feature protects
the motor in the event of the wiper operation being obstructed.
If the BCU does not receive the wiper park signal for a period of 16 seconds, when the wiper motor is active, the BCU
removes the power supply to the motor. The motor is disabled for a period of 3 minutes or until the ignition is switched
off and on again. Even after the 3 minute period has elapsed, the BCU will not automatically switch the motor on, to
prevent the risk of injury. The wiper switch must be moved off and then on to reactivate the wiper motor. The blocking
protection is active in all wiper switch positions and can only be reset by turning the ignition off.
Rear Wipers
The rear wiper has the following functionality:
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Intermittent operation
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Adjustable intermittent wipe period
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Continuous reverse wipe function.
Wiper Operation
The rear wiper is operated by the wiper column control switch. Pushing the switch forward to the first latching position
switches on the rear wiper. Moving the switch forward again to the non-latching position operates the rear wash/wipe
function.
When the rear wiper is selected on, the wiper is operated in an intermittent mode, performing one complete wipe cycle
at regular intervals. When reverse gear is engaged the rear wiper control module receives a reverse signal from the
LCM. If the rear wiper is on, the control module operates the rear wiper continuously. The continuous wipe will
continue until, reverse gear is disengaged or the rear wiper is switched off.
When rear wash/wipe is selected, the control module powers the washer pump for as long as the switch is held. When
the switch is released, the control module initiates five complete wipe cycles. The first three wipe cycles are each
accompanied by a 0.5 second operation of the rear washer pump. The final two cycles are to clear the tail door window
and do not have a washer pump operation. If intermittent remains selected, the rear wiper continues in intermittent
mode.
Intermittent Adjustment
The intermittent interval time of the rear wiper can be adjusted by the driver to wipe at between 1 and 30 second
delays. Adjustment is performed by switching the rear wiper on for a short time and then off again. The next switching
on of the rear wiper determines the delay period. The time lapse between the off and the next on signal is sensed by
the control module which sets this period as the requested time interval between wipes. If the next on signal is more
than 30 seconds after the off signal, the control module sets the time interval to the maximum 30 seconds.
Rear Wiper Motor Blocking Protection
The rear wiper control module contains similar logic to the BCU to protect the rear wiper motor in the event of the
wiper operation being obstructed.
Headlamp Wipers and Washers
The headlamp wipers and washers are only active when the headlamps are switched on and the ignition is on. The
wipers and washers are controlled by the BCU which limits their operation to preserve washer fluid in the reservoir.
With the ignition and lights on, headlamp wash/wipe is activated on the first operation of the wiper column control
switch in the wash/wipe position. The BCU then suspends headlamp wash/wipe activation for the next four operations
of the wash/wipe switch, with the headlamp wipers and washer activated on the fifth operation of the switch.
The BCU monitors the operation of the wash/wipe switch and maintains a counter to restrict headlamp wiper and
washer operation to every fifth operation of the wash/wipe switch. The BCU also maintains a timer which prevents a
second operation of the headlamp wipers and washers within a 3 minute period. The counter and timer are reset when
the ignition is switched off.
When headlamp wash/wipe is active, the BCU energises the washer pump twice per cycle. The headlamp washer
pump is powered for a 0.5 second period, 300 ms before the wiper motor starts. The BCU then initiates a 2 second
delay before powering the headlamp washer pump for a second 0.5 second period.