Wiper and Washer Systems: Description and Operation

Windscreen Wipers

Windscreen wipers
The windscreen wipers are driven by an electric motor with a reduction gear.

Brief component description
The following components are described for the wiper:
- Wash/wipe switch
- Steering column switch centre (SZL)
- Junction Box Electronics (JBE)
- Rain/light sensor (RLS)
- Auxiliary instrument
- Front wiper motor
- Rear wiper motor
- Windscreen washer pump
- Washer jets
- Headlight cleaning system

Wash/wipe switch
The wash/wipe switch is operated by briefly moving the lever. The wiper switch does not lock into place. Wiping of the rear window is switched on using the wash/wipe switch, by turning the cap on the wash/wipe switch.

Steering column switch centre (SZL)
The SZL forms the interface between the wash/wipe switch and the junction box electronics (JBE). The signals from the SZL are transmitted to the JBE via the PT-CAN.

Junction Box Electronics (JBE)
The JBE processes the signals from SZL and the driving speed. The JBE controls the load connection for the wiper motors. The load connection from the front wiper motor is created using two external relays. These external relays are located on the fuse and relay carriers within the engine compartment. The JBE controls the windscreen washer pump and the headlight cleaning system electronically. The washer fluid level switch transmits its information to the JBE.

Rain/light sensor (RLS)
In vehicles with the rain/light sensor (RLS) optional equipment, the RLS performs automatic interval control. The RLS is housed in the mirror base, on the windscreen. The wiper operation is therefore dependent on the intensity of the rainfall. The RLS transmits a request (for example to initiate wiping) to JBE, via the local interconnect network bus. The JBE provides the voltage supply for the RLS. If a vehicle is not equipped with RLS, the wiper operation interval is a preset value.

Auxiliary instrument
The auxiliary instrument receives information about the ambient temperature from the outside temperature sensor. The auxiliary instrument transmits the information to JBE, via the K-CAN.

Front wiper motor
The wiper motor is a rotary motor without an electronic component. The wiper motor is designed for two different wiper stages. The wiper motor is activated by means of two external relays. The end position (rest position) of the wiper motor is detected by a reset contact installed inside the wiper motor. The reset contact shifts ground to JBE as soon as the wiper motor has reached the end position (rest position). The reset contact is also used for monitoring the wiper motor.

Rear wiper motor
The rear wiper motor is identical to the front wiper motor in terms of design. The rear wiper motor is controlled electronically by means of an integrated relay in the JBE.

Windscreen washer pump
The windscreen washer pump is secured to the washer fluid reservoir. The windscreen washer pump is activated by the junction box electronics.

Washer jets
The washer jets are heated electrically. This prevents the washer jets freezing in cold weather. The washer jet heating system consists of heating resistors. The washer jets are controlled electronically by the JBE if the ambient temperate is below 3 °C.

Headlight cleaning system
The headlight cleaning system is offered as optional equipment. The JBE performs the activation of the washer pump for the headlight cleaning system. The headlight cleaning system only functions when the driving light is switched on. The headlight cleaning system is activated every fifth time the windscreen washer is operated. Switch-off of terminal R causes the repeat interlock and the counter for the number of washing procedure activations to be reset.












System functions
The following system functions are described for the wiper:
- Wipe functions
- Wash functions
- Headlight cleaning system
- Safety functions

Wipe functions
The wiper functions can be operated from terminal R. The following wiper functions are possible:
- Flick wipe
- Intermittent wipe
- Wiper stage 1
- Wiper stage 2
- Automatic wiping

Wash functions
The windscreen-washer functions are available as soon as Terminal R status is ON. To operate the windscreen washer, the wiper switch is pulled backwards (opposite direction of travel). To wash the rear window, the wiper switch must be pushed in the direction of travel.

Headlight cleaning system
When the low-beam headlights are switched on, the headlights are washed every fifth time the windscreen washer is operated.

Safety functions
When the wiper motor is switched on, the wiper motor is automatically switched off if the signal from the reset contact is not detected for approx 16 seconds. This is to protect against overloading. It is then only possible to switch on the wiper motor again after:
- approx. three minutes
- Terminal R OFF followed by Terminal R ON

We can assume no liability for printing errors or inaccuracies in this document and reserve the right to introduce technical modifications at any time.