Rain Sensor Description and Operation

Description

The rain sensor wiper system is a wiper system that, in addition to the normal wiper functions of OFF, MIST, manual low speed, manual high speed and WASH, provides automatic control of AUTO intermittent, AUTO low and AUTO high speeds. When the ignition switch is in the ON position, the rain sensor (A) is activated.

System Features

Basic principle: A light beam emitted by a diode is totally reflected from the outside of the windshield and then received by a photodiode. If there is water on the outside of the windshield, the beam is optically separated, and the amount of remaining beam is measured by the photodiode. When there is no water on the windshield, the light is fully reflected, so the degree of beam loss indicates how wet the glass surface is.

The rain sensor consists of two light-emitting diodes, two photodiodes, an optical fiber and a contact pad.

Wiper ECU Operation Control: the rain sensor transmits a signal, and the rain sensor detects rain water to send a command to the wiper ECU. The wiper ECU controls the wiper motor according to the signal. Contact influence: The rain sensor may malfunction due to the following conditions.

• Contamination of the measuring surface.
• Air bubbles between the windshield and the contact surface of the coupling pad.
• Movement of the coupling pad due to vibration.
• Damaged wiper blade.

Operating condition: If the engine is started with the wiper switch in the AUTO position, the rain sensor activates after one wiper cycle to inform the driver that the system is in AUTO mode.

If the rain sensor does not operate or is faulty, the driver must turn on the wipers manually.