Windshield washing and wet arm heating

In the case of windshield washing, water is sprayed onto the windshield glass and then wiped away by the wiper.

The washer jets are integrated directly in the wiper arm so that also at high vehicle speeds the windshield glass is provided with sufficient water.

To ensure that the wash system also functions reliably at low outside temperatures, a heating wire is integrated in the water hose in the wiper arms (wet arm heating).

Brief description of components

Wiper module

The wiper module contains the electronics for controlling the wiper, the washer pump and the wet arm heating. It is connected to the K-CAN SYSTEM data bus. The wiper module is securely connected to the wiper motor.

Steering column switch center (SZL)

The steering column switch center 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 center.

Wiper switch

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.

The switch positions of the wiper switch are transferred from the steering column switch center via the data buses BYTEFLIGHT and K-CAN SYSTEM to the wiper module.

Washer pump

The washer pump pumps the water from the washer reservoir to the washer nozzles in the wiper arms. It is activated directly by the wiper module.

Wet arm heating

The wet arm heating consists of a heating wire integrated in the washer hose in the wiper arm. The heating wire is supplied with current by the wiper module.

Central Gateway Module (ZGM)

The central gateway module links the data buses

Main functions

Windshield washer

Operating the wiper switch in the position ”windshield wash” causes the wiper module to activate the washer pump and spray water through the washer nozzles in the wiper arms onto the windshield. Depending on the country, two different washing programs can be coded in the wiper module:

If the switch was operated for longer than one second, when it is released 3 more wiper cycles are carried out and the windshield is wiped dry (after-wipe program).

If the switch was operated for less than a second, there is no wiping dry.

Time monitoring

A higher level time monitor protects the washer pump against thermal overload.

If the washer reservoir is full, the washer pump is switched off after a maximum of 2 minutes by the time monitor.

If the level switch in the washer reservoir detects that the washer reservoir is almost empty, the washer pump is switched off after 15 seconds.

Wet arm heating

Depending on the outside temperature and battery voltage, as of terminal R On the wet arm heating is activated by the wiper module. When the wet arm heating is active, current flows through the heating wires in the water hose of the wiper arm. The heating wires warm up and thus warm the water in the water hose.

The heating wires are supplied with current by means of a pulse-width-modulated signal (PWM signal). This enables control of the heat output.

Service functions

Cleaning the washer jets

The function ”Clean washer jets” is used to clean as well as check the washer nozzles. Following repair work, the function can be used to check the spray angle.

The cleaning function is triggered as follows: