Rear screen wiper (Electrical)

REAR SCREEN WIPER

The rear screen wiper is controlled from a latching push button switch located on the right hand side of the instrument pack. A second non-latching switch, also on the right hand side of the instrument pack, operates the rear screen wash/wipe facility.

The CCU controls all functions of the rear screen wiper. The wiper will not operate if; the tail door window is lowered or not calibrated or, on 3 door models, if the roof is removed. The wiper motor drives a geared wheel which has three tracks on one face. The tracks communicate with three contacts and provide signal information to the CCU.

When the wiper is operating, one of the tracks signals the CCU of this condition. When the wiper reaches its ’out wipe’ position, the second of the tracks completes a circuit which signals the CCU of this position. When the wiper reaches its off-screen position, the third track signals the CCU, which removes the power supply from the reverse relay.

The off-screen park is operated by the CCU reversing the motor rotational direction. This, in turn, activates a cam within the motor linkage, lengthening the stroke of the wiper and parking the wiper off-screen.

The CCU operates the wiper motor via a forward and a reverse relay. The forward relay is energised when the wiper is operating in programmed, intermittent and slow mode. The reverse relay is energised to reverse the rotational direction of the motor to activate the off-screen park function.

The CCU operates the rear screen wiper in four different modes; off-screen parked, intermittent, programmed and slow.

Off-Screen Parked

When the rear screen wiper is not selected, no power is supplied to the wiper relays and the wiper is parked off-screen.

Intermittent

With the ignition on, the rear window wiper switch selected on, the tail door window closed and, on 3 door models, the roof is on, the wiper operates intermittently with a fixed delay of five seconds between wipes.

Programmed

If the ignition is on, the tail door window is closed, on 3 door models the roof is on and the rear screen wash/wipe is selected, the CCU operates the wiper in programmed mode, washing and wiping the rear screen until the wash/wipe switch is released.When the switch is released, the washer stops and the CCU continues to energise the forward relay for a further six seconds before parking off-screen.

Slow

If the ignition is on, the tail door window is closed, the front screen wipers are on, on 3 door models the roof is on and reverse gear is engaged, the CCU operates the wiper in slow mode, wiping the rear screen until reverse gear is disengaged or the front wipers are turned off.

Intermittent, Programmed, Slow operation to Off-Screen Parked

The off-screen park function operates as follows: The CCU energizes the forward relay until the rear screen wiper out wipe sense is detected. The forward relay is then de-energised and the reverse relay is energised. The reverse relay operates the motor in the opposite direction, which lengthens the stroke of the wiper arm. When the wiper arm reaches the off-screen position, the CCU senses a signal from the applicable contact in the wiper motor and de-energizes the reverse relay.