RAIN SENSOR
id091900001000
Purpose
• The rain sensor detects the amount of rainfall and calculates the wiper operation speed required to perform automatic wiper operation (auto wiper system) depending on the amount of rainfall, and outputs a windshield wiper control signal to the BCM (Body Control Module).
Function
Rainfall detection function
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• The LED in the rain sensor emits infrared light which is reflected off the windshield via the lens and then received by the photodiode in the rain sensor. If the rate of reflected infrared light is reduced, it is determined that rain is contacting the windshield, and the intensity of the rainfall is calculated from the amount of reflection rate reduction. The calculated amount of rainfall is used for operating the wiper at the optimal speed.
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Caution
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• In the windshield is in the following conditions, the rain sensor cannot detect the rainfall amount correctly, which could cause the windshield wiper to operate incorrectly.
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― A sticker or label is attached to the rain sensor in the windshield.
― Dirt is adhering to the windshield in the rain sensor installation area.
Initial setting function
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• When the ignition is switched ON, the rain sensor detects and records the transparency of the windshield surface, which varies depending on wear and accumulation of dust. As a result, the rain sensor determines the optimal speed (LO/HI) for the windshield wipers and sends the windshield wiper operation signal to the BCM.
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• Initial setting is performed everytime the ignition is switched on.
Sensitivity adjustment function
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• While the auto wiper is operating, sensitivity of the rain sensor can be adjusted by operating the sensitivity adjustment volume on the wiper and washer switch which changes the volume signal input to the BCM.
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― Adjust the sensitivity of the rain sensor between 1 (low sensitivity) to 6 (high sensitivity) by operating the sensitivity adjustment volume according to the rain condition.
On-board diagnostic function
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• If a rain sensor malfunction or communication error between the rain sensor and BCM is detected with the ignition switched on, the sensor sends an error signal to the BCM. The BCM detects DTCs based on the error signal from the rain sensor.
Construction
• The rain sensor is installed to the bracket in the upper center part of the windshield.
• The rain sensor is integrated with the auto light sensor.
• The rain sensor consists of the lens, LED, photodiode, and CPU, and sends/receives signals between the BCM using serial communication.
Operation
Operation with no rainfall contacting windshield
1. Infrared light is emitted from the LED in the rain sensor towards the windshield.
2. The emitted infrared light reflect off the windshield.
3. The infrared light reflected off the windshield is received by the photodiode in the rain sensor.
4. When the photodiode receives the light, the microcomputer in the rain sensor calculates the rainfall amount from the reflection rate, and sends a windshield wiper control signal to the body control module (BCM).
Operation with rainfall contacting windshield
1. Infrared light is emitted from the LED in the rain sensor towards the windshield.
2. Emitted infrared light goes through the windshield and penetrate rainfall on the windshield.
3. The infrared light which cannot penetrate is reflected off the windshield and is received by the photodiode in the rain sensor.
4. When the photodiode receives the light, the microcomputer in the rain sensor calculates the rainfall amount from the reflection rate, converts this to an electric signal, and sends a windshield wiper control signal to the BCM.
Fail-safe
• If there is a malfunction in the rain sensor or communication error between rain sensor and BCM, and if the BCM detects a signal error ten times in a series, the operation before the malfunction was detected is continued.
• If the rain sensor detects rainfall and then detects no change in the detected amount after the wipers have been operated approx. two times, the windshield is determined to be dirty and windshield wiper operation is stopped.
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― If the windshield is dirty, set the wiper and washer switch to LO or HI position to operate the windshield wiper. Or, remove the dirt from the windshield, then operate the auto wiper.
• If the temperature sensor in the rain sensor detects approx. 14 degrees F (-10 degrees C) or less when the ignition is switched ON, the windshield wipers do not operate even though it may be snowing.
