B1905 Rain Sensor Fault 1: General Description

FAM controls the low/high wiper relay according to rain sensor signal when the wiper auto switch is turned to ON under IG ON.

NOTE: The rain sensor is mounted on the interior side of the front windshield glass behind the rearview mirror. If driver turns the wiper switch to AUTO, this signal is inputted to FAM by LIN communication.
FAM transmits 5 steps of signals (Slow ↔ Fast) from the wiper auto switch to the rain sensor.
At the slowest step among the INT switch, the rain sensor becomes the most insensitive status.
At the fastest step among the INT switch, the rain sensor becomes the most sensitive status to measure the amount of rain.
So, the sensitivity of the rain sensor depends on the steps of the INT switch.
The rain sensor transmits the desired speed of a wiper by duty signal to FAM.

Fig 1: Rain Sensor And FAM Schematic Diagram

Courtesy of HYUNDAI MOTOR CO.

[FAM output signal (FAM → Rain sensor)]

FAM transmits sensitivity step signal from INT switch to the rain sensor by pulse signal.

Fig 2: FAM Output Signal (FAM → Rain Sensor)

Courtesy of HYUNDAI MOTOR CO.

[FAM input signal (Rain sensor → FAM)]

The Rain sensor transmits moisture status and the desired wiper speed to FAM by pulse signal.

Fig 3: FAM Input Signal (Rain Sensor → FAM)

Courtesy of HYUNDAI MOTOR CO.

* The Rain sensor has various outputs according to each modes as below. (Duty cycle changes)

Rain sensor output signal (Rain sensor → FAM)

RAIN SENSOR OUTPUT SIGNAL REFERENCE

NO	MODE	Duty Cycle
1	OFF	9.5% +/-3%
2	Error 1 detection	23.8% +/-3%
3	Error 2 detection	38.0% +/-3%
4	Error 3 detection	52.4% +/-3%
5	Rain detection	66.7% +/-3%
6	Low speed demand	81.0% +/-3%
7	Fast speed demand	95.2% +/-3%
Every signal cycle is 15 mSec.