Wiper Switch: Description and Operation
Wiper/Washer System
Description
Wiper switch
All wipe/wash functions can be switched on with the wiper switch as of terminal R (ignition lock in position 1).
The wiper switch can be switched to intermittent wipe, stage 1 and stage 2. These settings are coded by means of two lines leading to the general module. They are each switched to ground
On vehicles equipped with the special option automatic interval control (AIC), in the "intermittent" switch position, the intermittent wipe function is controlled by a rain sensor (refer to functional description for automatic interval control).
Intermittent mode
A knurled wheel with a potentiometer is integrated in the wiper switch. This makes it possible to set four different intervals. These times are also controlled according to road speed. The faster the vehicle is driven, the shorter the interval.
On vehicles equipped with automatic interval control (AIC), the sensitivity of the rain sensor can be influenced with the thumbwheel.
Wiper motor
The wiper motor is configured for two different wiper speeds. The load is switched via two external relays.
The end position (park position) of the wiper motor is recognized by means of a reset contact integrated in the motor. This contact switches ground to the general module when the motor has reached its end position.
The reset contact is also used for monitoring the wiper motor. If the contact signal is not received for 16 seconds with the wiper motor switched on (e.g. dry running), the wiper motor is switched off in order to protect it from overloading.
The wiper is not switched on again before it has been switched off and a lock-out time of 3 minutes has elapsed.
The wiper speed is set at the wiper switch. If automatic interval control is not installed, the wiper speed will be additionally controlled according to the road speed. The following settings apply:
When stage 2 is switched on, stage 1 cuts in at > 205 km/h to prevent the wiper arm from lifting.
On vehicles with the optional extra automatic interval control (AIC), the windshield wipers are not controlled according to road speed.
Headlight washer
The drive for the headlight washer pump is actuated via an external relay.
The headlight wash function is triggered every fifth time wash or intensive wash is activated when the headlight or parking lights are switched on. The headlights are sprayed twice.
The headlight wash function is blocked for 3 minutes at the end of a wash cycle.
Switching off terminal R resets the repeat lock-out and the counter for wash operations. When terminal R is switched on again with the lights on, the headlight wash function can be activated immediately.
Rear Window Wiper
The rear window can be cleaned and wiped with the rear wiper/washer system. The system is controlled by a separate control module that forms one module together with the wiper motor.
Operation
Rear window wiper
Terminal R must be switched on to enable the "rear window wipe" function. The rear window wiper is switched on by pressing forward the wipe/wash switch to the first switch stage (in forward direction). The rear window wiper then runs at a fixed wipe interval.
An electronic switch (Hall sensor) is integrated in the rear window wiper for the purpose of detecting the park position
Rear window wash function
The "rear window wash" function is activated by momentarily pressing the wiper switch or by pressing it beyond the "rear window wipe" position.
Following activation, a wash program is triggered that consists of three wash cycles and two wipe cycles. Renewed activation is possible during the last wipe cycle. The wash pump is activated by the control module for the rear window wiper.
Programmable wipe intervals
The interval time of the rear window wiper can be programed as follows:
- Ignition lock in position 1 or 2 (terminal R ON)
- Press wiper switch forward to the first switch position, the rear window wiper is activated.
- Pull back wiper switch to "rear window wiper OFF" position before the wipe cycle is completed.
- Wait for the required interval time to elapse and switch on the rear window wiper. The time between switch OFF and switch ON is stored as the interval time.
The wiper switch must not be set in the "rear window wash" position when programming the interval time.
A maximum interval time of 30 seconds can be programed.
Special functions
Reverse
If reverse gear is engaged with the rear window wiper switched on, the wiper switches from intermittent mode to continuous wipe mode.
Jamming protection
A jamming protection facility is integrated in the control module in order to avoid overloading of the wiper motor in the event of the wiper jamming. A jamming situation is detected by the Hall sensor integrated in the wiper motor and by an internal short-circuit detection facility in the electronic components. The wiper is switched off if jamming is detected.