Functional description, see BMW SI Technology:
TIS -> Document -> SI Technology:
The windshield wipers, the windshield washing pump and the pump for the headlight washer system are controlled by the Junction Box Electronics (JBE).
The wiper switch is connected to the steering column switch cluster (SZL). The switch states are sent across F-CAN to the DSC and from the DSC across PT-CAN to the JBE.
In the automatic mode, the rain/driving light sensor (RLS) registers the rain intensity. It sends the data on the LIN bus to the Roof Function Center (FZD). The FZD then sends the rain intensity on the K-CAN to the JBE.
To prevent the washer nozzles of the washer system from freezing, there is a washer nozzle heating. The JBE controls this heater depending on the outside temperature.
The JBE receives the outside temperature from the instrument cluster across the K-CAN.
The washer nozzle heating is activated together with the heater for the door mirrors.