The windscreen wipers are driven by means of an electric motor with a step-down gear mechanism. The wiper electronics (wiper module) is integrated directly in the wiper motor. The wiper switch is connected to the steering column switch centre. The system enables windscreen wiping in two different speed stages as well as flick wipe and intermittent operation.
As special equipment, a rain sensor for automatic control of the wiper can be fitted.
The wiper module contains the electronics for control of the wiper motor and for reception and evaluation of the bus data of the data bus K-CAN SYSTEM. The wiper motor is firmly linked to the wiper motor.
The wiper motor is designed as a 2-brush motor with an integrated step-down gear mechanism. On reaching the reversal positions, the wiper arms are returned by reversing the polarity of the motor.
The reversal positions are registered by electronic Hall sensors integrated in the wiper motor. It is necessary to adjust the upper reversal position when carrying out repairs on the wiper mechanism (see service functions).
The steering column switch centre registers the signals of the switches and sensors installed in the steering wheel. It also controls all the components located on the steering wheel and the steering column. Information is received and sent via the data bus BYTEFLIGHT.
The wiper switch is connected to the steering column switch centre.
The wiper stages intermittent wipe, stage 1 and stage 2 are selected with this switch. The washer pump is activated by pulling back the wiper switch.
There is also a button on the wiper switch that can be used to activate wiping operation via rain sensor (special equipment). Operating the switch switches off all wiper stages.
The intermittent periods can be varied by means of the four-stage rotary switch (knurled wheel) on the wiper switch. If a rain sensor is fitted (optional extra), the sensitivity of the sensor can be varied with the knurled wheel.
The switch positions of the wiper switch are transferred from the steering column switch centre via the data buses BYTEFLIGHT and K-CAN SYSTEM to the wiper module.
The rain/driving light sensor is attached to the windscreen. It registers the rain intensity to control the wiper intervals and the surrounding brightness to control unit the automatic lighting function.
The rain sensor detects wetness on the windscreen using an optical process. Here, a light diode in the control unit emits infrared light which is reflected by the windscreen glass. The reflected light is registered and measured by a receiver diode. If there is water on the windscreen, the light reflection changes and less light reaches the receiver diode.
The rain sensor sends the request for wiper activation via the data bus K-CAN SYSTEM to the wiper module. If intermittent operation is switched on, a wiping cycle is activated or the wiper speed is increased.
The sensitivity of the rain sensor can be varied by means of the rotary switch (knurled wheel) on the wiper/washer switch.
The central gateway module links the data buses
Switching on: The wiper switch has two switch position in the upward direction. If the switch is moved upwards to the first pressure point, intermittent operation or wiper stage 1 (if rain sensor is fitted) is activated. Moving the switch upwards once again increases the wiper stage (from intermittent to stage 1 or from stage 1 to stage 2).
If the wiper switch is moved beyond the first pressure point to the end stop, wiper stage 2 is switched on immediately.
If the wiper is in intermittent operation, the knurled wheel in the wiper switch can be used to reduce or increase the intermittent period.
Downshifting the wiper stages:each setting is selected at one stage at a time by pressing down the switch. With the wiper switched off, a flick wipe is run.
Axial operation:the wiper switch can be additionally operated in axial direction. Operating the wiper switch in axial direction switches off all wiper stages and activates the rain sensor (if fitted). As acknowledgement for the driver, a green LED lights up in the wiper switch.
Rain sensor mode:if the wiper is in the rain sensor mode, a flick wipe can be carried out by pressing the wiper switch downwards. If the wiper switch is pressed upwards, wiper stage 1 or 2 are switched on and the rain sensor mode is disabled. The green LED in the wiper switch goes out.
The sensitivity of the rain sensor can be increased or decreased by means of the knurled wheel on the wiper/washer switch. If the sensitivity is increased (turn knurled wheel upwards), one wiping cycle is carried out immediately.
For safety reasons, the rain sensor is switched off when terminal R is switched off.
The lower return position of the windscreen wiper depends on the set wiper stage. With wiper stage 1 or 2 switched on, it is higher than for intermittent wipe.
When the wiper is switched off, the wiper blades are stored in the rest position.
In order to increase the service life of the wiper blades, there are two different rest positions in which the wiper blades are directed either upwards or downwards.
The rest position is changed after 4 days. The wiper module detects the time limit, as it compares the time and date information supplied by the instrument cluster via the data buses with the time information stored in the wiper module.
As the instrument cluster only transfers the time and date as of terminal R On, the rest position is changes after the following conditions:
There is no automatic change of the rest position when the vehicle is parked.
Snow mode
If there is snow on the windscreen, ”wedges of snow” are formed in the upper and lower areas of the windscreen; this can lead to blocking of the wiper. In order to prevent jamming deactivation, the wiper range is reduced within the permitted limits.
In this snow mode, the wiper control attempts continuously to enlarge the wiper range.
Emergency operation
If the wiper module detects an increased load in wiper stage 2 in the mid wiper range, there is a reduction of the wiper speed to stage 1.
Jamming protection
If the wiper control is unable to wipe free the legally prescribed windscreen area due to sluggishness or jamming, the jamming protection is triggered.
When jamming is detected, the wiper is first switched off for 1 second. Then, 3 attempts at reactivation are made. If there is still a jam, the wiper arms are halted in the lowest possible position and come to a standstill there.
For reasons of safety (risk of injury), once the jamming protection has been triggered there is no automatic reactivation. Activation only takes place when the wiper is switched on by means of the wiper switch.
When the jamming protection is active, the washer pump and the pump for the headlight cleaning are locked.
The wiper blades can be changed in the fold-out position.
The fold-out position is reached as follows:
The wiper only moves to the park position when a wiper stage is activated after terminal R has been switched on.
In order to simplify assembly and setting of the wiper arms, the wiper motor can be moved to the lower rest position using the service function assembly position.
The service function is selected via the BMW diagnosis system at ”Service functions” - ”Body” - ”Wiper” - ”Assembly position”.
In the service function, the wiper is activated briefly and moves upwards approx. 30 cm. The wiper then moves into the lower rest position.