Wipers and washers (Rear wipe): Description and operation

Rear wipe

Rear wipe operation will only activate when the following conditions are met: l Ignition switch is in position II. l Rear wipe switch is operated.

Operating the rear wiper switch provides an earth input to the BCU. The BCU tells the IDM to activate the rear wiper relay, which provides battery voltage to the wiper motor through the normally closed contacts of the park switch.

Rear wash

Rear wash will only operate when the following conditions are met: l Ignition switch is in position II. l Rear wash switch operated.

Operating the rear washer switch for longer than 0.4 second allows the rear washer pump motor and rear wipers to run as long as the switch is held. The wipers run for 4 seconds after the rear washer switch is released. Flicking the rear washer switch energises the rear washer pump motor for 0.4 second.

The rear washer operation has a higher priority than the intermittent wipe operation. If the intermittent wipe is active when a rear washer operation is initiated, the wash cycle executes and the intermittent wipe is re-instated at the end of the washer operation.

Wiper park switch

The park switch allows the wipers to come to rest in the park position when the wipe switch is turned off in mid-wipe.

The park switch consists of a positive and a negative contact. These two contacts are described as closed at park and closed when operating. When the wipers first start, the park switch is in the closed at park position. A relay controls battery voltage to the motor. Battery voltage passes through this relay contact to move the wiper motor from the park position.

When the motor moves, the park switch moves to the closed when operating position. Battery voltage to this relay contact is direct from fuse 19. Battery voltage passes through this contact to keep the wiper motor running. The wiper motor operates for one complete revolution until the park switch moves to the closed at park position again.

Switching off the wipers removes battery voltage from the closed at park contact. When the wipers reach the closed at park switch an earth is applied and the motor stops abruptly.

Headlamp power wash

Headlamp power wash activates when the following conditions are met: l Ignition switch in position II. l Headlamps switched on. l Front wash switch operated. l BCU counter allows headlamp power wash.

Operating the front washer switch with the headlamps switched on energises the IDM, supplying a voltage to the headlamp powerwash relay, which operates the headlamp powerwash pump and increments a counter within the BCU. This counter prevents the headlamp powerwash pump from operating every time the front washer switch is activated. Headlamp powerwash is only operational every third front wash cycle, providing the headlamps are on. The counter resets when the ignition switch is turned off.

When the BCU permits headlamp power wash operation, the pump motor operates only for 0.5 second.