Front Wiper System

92 Front wiper system

The front wiper system features two wiping speeds and an interval setting. They are controlled by means three positions of the right-hand steering column stalk. The individual wiping intervals are set via a potentiometer in the steering column stalk.

A rain sensor integrated in the foot of the interior mirror is available as an option. When it rains, the wiping speed is automatically and continuously selected to suit the conditions. In vehicles with rain sensor, the sensitivity of the rain sensor is adjusted via the potentiometer in the steering column stalk. Having the wiper controlled via the vehicle electrical system control unit means that additional information is available for automatic regulation of the wiping speed and for error diagnosis. For example, the control unit can tell from data transmitted by the sun-position sensor in the automatic climate control system that it is night and can then regulate the wiper mode more sensitively if the rain sensor is activated. The wiping speed for the wipe/wash function is also variably controlled. The wiper function is automatically set to level 2 at speeds above 110 km/h to provide the driver with a clear view as quickly as possible.

Operation of the wiper motor
The front wiper system is supplied with the necessary voltage from the vehicle electrical system control unit, via a short circuit-proof output module and a reverse voltage protection and change-over relay. The wiper/washing functions of the stalk control are read in in the steering column module and converted here into CAN signals which are subsequently evaluated in the vehicle electrical system control unit. Power supply to the wiper motor is interrupted immediately when "ignition off" state applies. When the ignition is switched on again, the wiper is moved into its end position, provided that the wiper functions (intermittent, wiper 1, wiper 2) are off.

The wiper motor is permanently connected to ground and is supplied with positive potential in its respective switching positions. After deactivation of the respective switching positions and in intermittent mode the wiper motor continues to be supplied with positive potential until it reaches its home position. A load-switched ground signal is sent to the level 1 terminal immediately after cut-off of the positive potential. The wiper motor thus operates as a generator in short-circuit operating mode and is decelerated.

Home position is scanned by a disk cam integrated in the wiper motor.

If home position is not detected within the time tEND as a result of a malfunction, the control system will switch to direct operating mode. Operation of the wiper can then only be continued in positions 1 and 2, whereby the wiper is shut down by means of the wiper switch without returning to its home position.

Technical data on the wiper motor