Rain Sensor Module (RSM)

The rain sensor module (RSM) (7/149) determines whether there is water on the windshield. The sensor assesses the volume of water on the windshield and the prevailing exterior light conditions. This information is then sent, via the upper electronic module (4/70), to other control modules in the car on the controller area network (CAN). These control modules in turn ensure that the windshield wipers are set to the correct speed. The rain sensor senses if the windshield is dirty or covered with traffic film and automatically compensates accordingly. The rain sensor also senses heavier splashes on the windshield. The windshield wipers are then operated at top speed.

The rain sensor module (RSM) communicate with the upper electronic module (UEM) using serial communication. Power is supplied from the upper electronic module (UEM) via the power supply signal EXT. X, when the ignition key is in positions I or II. The rain sensor is active for 10 minutes after the ignition has been switched off.

The steering wheel module (SWM) (3/254) transmits a signal about the position of the windshield wiper stalk via LIN-communication to the central electronic module (CEM) (4/56). The central electronic module (CEM) sends this information onwards on the controller area network (CAN) to the upper electronic module (UEM). If the stalk is moved to the intermittent wiping/rain sensor position, the upper electronic module (UEM) transmits this data to the rain sensor module (RSM) which is then activated.

The rain sensor module (RSM) sends information via the upper electronic module (UEM) to the central electronic module (CEM) which then deploys the wiper motor. The sensitivity can be adjusted using the collar on the wiper stalk.

If a fault occurs in the rain sensor module (RSM), the upper electronic module (UEM) transmits an error message to the central electronic module (CEM). If there is a fault message when the rain sensor is active, the central electronic module (CEM) selects top speed for the windshield wipers until the windshield wiper stalk is moved from the intermittent/rain sensor position. If the fault recurs, intermittent wiping will be activated when the wiper stalk is next moved to the intermittent/rain sensor position, although only at a fixed interval.