Mazda RX-8 2009 Service Highlights page 237

RAIN SENSOR FUNCTION
Rainfall detection function
! The LED in the rain sensor emits infrared light which is reflected off the windshield via the lens sensor 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.
Sensitivity Adjustment Function
! By changing the sensitivity adjustment volume, installed on the wiper and washer switch, the sensitivity of the
rain sensor can be freely adjusted.
Initial Setting Function
! When the ignition switch is turned to the ON position after replacing the rain sensor with a new one, the initial
setting is stored after verifying the windshield condition.
! The initial setting of the rain sensor can be performed using the specified procedure.
— Refer to the Workshop Manual for the initial setting procedure.
On-board Diagnostic Function
! If there is any malfunction in the rain sensor, the rain sensor notifies the auto light/wiper control module of the
malfunction and a DTC from the auto light/wiper control module is detected.
! If there is a communication error between the rain sensor and auto light/wiper control module, the rain sensor
notifies the auto light/wiper control module of the error and a DTC from the auto light/wiper control module is
detected.
Fail-Safe Function
! If the rain sensor detects rainfall and then detects no change in the detected amount after the wipers have been
operated two times, the windshield is determined to be dirty and windshield wiper operation is stopped.
— If the windshield is dirty, turn the wiper and washer switch to the 1 or 2 position to operate the windshield
wipers. Or, remove dirt from the windshield before operating the auto wiper.
! When the temperature sensor inside the rain sensor detects approx. -10 $C {50 $F}or less when the vehicle
speed is 0 km/h, the windshield wipers do not operate.
End Of Sie
RAIN SENSOR CONSTRUCTION/OPERATION
Warning
! If vehicle servicing such as car washing is performed with the ignition switch turned to the ON
position, and the wiper and washer switch is in the AUTO position, the windshield wipers may
operate automatically. Always turn the ignition switch, and the wiper and washer switch off before
performing servicing such as the car washing; otherwise a pinched hand or fingers could result in
injury or a wiper system malfunction.
Caution
! In the following cases, the rain sensor cannot detect the rainfall amount correctly which could
cause a windshield wiper malfunction:
— A sticker or label is adhered to the windshield above the rain sensor.
— The windshield is dirty above the rain sensor.
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WIPER/WASHER SYSTEM
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