Wipers and washers (Body control unit)

Wipers and washers

Front and rear wash/ wipe operations are controlled by the BCU via the IDM.

Front wipers and washers When front intermittent wipe is selected using the wiper switch on the column stalk, the BCU signals the IDM to operate the wiper motor. The IDM then supplies a voltage to the normal speed winding of the wiper motor for a period of no longer than 500 ms. The timed feed ensures the wiper motor operates, but does not complete more than a single wipe of the screen. The BCU checks the position of the delay switch to determine the delay period which should be utilised for the intermittent wipe operation. The delay period of the front intermittent wipe is maintained until the wiper switch is moved to the off, normal or fast speed position, or the delay period is changed.

When front intermittent wipe is selected, a delay period of 500 ms will be incurred before the wipers operate. This delay prevents the occurrence of a wipe action when the wiper switch is changed to the off position from the normal or fast modes of operation.

To enable the front intermittent wipe facility, the BCU checks the state of the following inputs: l Ignition state. l Front intermittent wiper switch. l Front intermittent wiper rate.

If the ignition switch is in the off or crank position, the front wipers are not active and the front wiper enable output is switched off.

If the option to initiate a wipe action in addition to a front screen wash action has been configured in the BCU, the wipers will operate 400 ms after the washer pump becomes active. If the washer switch is released within 400 ms, the wipers will not be activated. If a washer switch is pressed for longer than 400 ms, the BCU will operate the wipers after an initial delay of 400 ms, and will continue to operate for as long as the washer switch is depressed plus an additional 4 seconds.

The front wash/ wipe programme can be configured to operate in one of two ways: l Option 1 – normal. l Option 2 – no wipe.

The BCU checks for the following inputs: l Ignition state. l Front washer pump switch.

The BCU can provide the following wash / wipe outputs depending on the logic states prevailing: l Front wiper enable. l Front wash/ wipe in progress flag.

In the event of a communications link failure occurring while the front wash/ wipe programme is in operation, the front wiper enable output is switched off.

Rear wipers and washers The rear wiper is initially operated for a period of 4 seconds when the rear wiper switch is pressed, to complete two full cycles. After this, the rear wiper will operate every other time the front wiper completes a wipe operation. During the wipe operation, the front and rear wipers are synchronised, and changes to the delay period during intermittent wipe will change the delay period for both front and rear wipers.

Operation of the rear washer switch causes the washer motor to operate for as long as the switch is operated. The wiper also operates while the switch is depressed and for a further 4 seconds after the switch is released.

The BCU checks for the following inputs to determine when to provide the rear wiper enable signal: l Ignition state. l Rear wiper switch. l Front intermittent wiper rate. l Front intermittent wiper switch.