Rain Sensor: Testing and Inspection

Inspection

1. Wiper blade
Check the wear of wiper blade. If it is excessively worn, wipe out clean to sense the rain amount accurately.
2. Coupler
Check the coupler surface on the windshield glass for any excessive bubble. Presence of bubble within the sensing range prevents the accurate sensing. Check the coupler for its correct installation. Especially, check the sensing points of the coupler whether it is located within the opening area of ceramic coating area. If the sensing area around the ceramic coating area is blocked, infrared light of the sensor cannot penetrate to result in the failure of accurate sensing.
3. Glass
Check the windshield glass surface beyond the sensing range for the excessive wear, scratch or crack. Though, sensor covers the wear to a certain level, sensor fails to sense accurately if it exceeds a certain level. This is confirmed by the self-diagnosis of sensor.
4. Exterior cover
Check the exterior cover of rain sensor. Check the cover locking for loosening whether it causes impact on the sensor. In addition, check glass or inside rear view mirror for any interference.
5. Spring clip
Check the spring clip after removal of exterior cover if the rain sensor is disconnected from the coupler.
6. Connector
(1) Check the terminal inside the connector and wiring for compression, and check the terminal whether it is inserted and locked correctly.
(2) In addition, check the wiring connector and rain sensor connector for assembly and confirm to prevent poor connection.
7. Relay
Check the low-speed relay and high-speed relay for normal operation. Since wiper motor cannot operate when melted, wiper blade does not respond in auto mode.
8. Circuit
Check the circuits. Especially check the variable resistance of the wiper switch. Turn the variable resistance knob step by step from slow to fast to check this out. It is normal if it wipes once at every click. (This is so called single wipe.) In addition, check the wiper motor parking signal whether it operates correctly. If parking signal is not inputted, it may cause more wiping than normal, and wiping is not smooth due to the inaccurate shift timing.


Self-diagnosis

1. Rain sensor has 3 types of self-diagnosis test mode as follows.
(1) FAULT 1 self diagnosis
When the error is detected in inside, software or hardware, error is always expressed in terms of rain sensor. This signal detects the problem of sensor module.
(2) FAULT 2 self diagnosis
If the rain sensor servo operating point is above the predetermined one by the software, it means FAULT A. This phenomenon occurs if the windshield glass is damaged where coupler is installed, or sensor is removed from the coupler.
(3) FAULT 3 self diagnosis
Rain sensor shows that input signal is not detected from rain sensor to BCM at least for 0.5 second. Wiper does not operate without input signal. It cannot be known by the INT volume sensitivity adjustment.

NOTE:
In the auto mode, wiper continues to operate in the same mode even if sensor detects the input signal, but it stops operation when turned off.

2. Types of failures when INT volume sensitivity is adjusted.
Following is the self-diagnosis by the sensitivity adjustment and wiper motion.
(1) Wiper switch sets the INT volume sensitivity to 1st level in IGN ON and AUTO position.
(2) Shift the sensitivity from 1 to 2 in this condition.
(3) If wiper operates once, then it is in FAULT 2 self-diagnosis. In service shop, check the windshield glass for the damage and rain sensor for its installation.
(4) Shift the sensitivity from 2 to 3 after checking the above mentioned 3).
(5) If the wiper operates once, then it is in FAULT 1 self diagnosis, and the rain sensor should be replaced with new one.