Rain Sensor: Description and Operation

Rain sensor

Rain sensor




The rain sensor module (RSM) (7/149) senses water on the windshield. The rain sensor (RSM) assesses the information based on volume of water on the windscreen and the prevailing exterior light conditions. This information is transmitted via the central electronic module (CEM) (4/56) on to the wiper motor module (WMM) (6/1) via serial communication. The wiper motor module (WMM) in turn ensures that the windscreen wipers are set to the correct speed.
The rain sensor module (RSM) senses if the windscreen is dirty or covered with traffic film and automatically compensates accordingly. The rain sensor module (RSM) also senses heavier splashes on the windscreen. The windscreen wipers then operate at top speed.
The rain sensor module (RSM) communicates with the central electronic module (CEM) via serial communication. Power is supplied via the relay for extended feed. The relay is checked by the central electronic module (CEM) and is activated when the ignition is in position I or II. The rain sensor module (RSM) is powered for 3 seconds after the ignition has been switched off.
The steering wheel module (SWM) (3/130) transmits the signal via the LIN communication to the central electronic module (CEM) indicating the position of the windshield wiper stalk and the status of the rain sensor switch. If the rain sensor switch is activated on the wiper stalk, the central electronic module (CEM) transmits the information to the rain sensor module (RSM) which is activated.
The rain sensor module (RSM) transmits information to the wiper motor module (WMM) via the central electronic module (CEM). The sensitivity can be adjusted using the collar on the wiper stalk.
If a fault occurs in the rain sensor module (RSM), the central electronic module (CEM) transmits an error message to the wiper motor module (WMM). If there is a fault message when the rain sensor module (RSM) is active, the wiper motor module (WMM) selects top speed for the windshield wipers until the rain sensor (RSM) is deactivated. If the fault recurs, wiping will only be activated when the wiper stalk is next moved to the single sweep or slow speed position.