Rain / Driving Light / Solar Sensor (RLSS)

Rain / Driving Light / Solar Sensor
The rain / driving light / solar sensor groups the following sensors and components into one control module:
- Rain sensor: consisting of 3 individual sensors arranged in a semicircle around the driving light sensor, picking up the precipitation quantity on the windscreen.
- Driving light sensor: consisting of 2 photo diodes that pick up the brightness of the ambient light and of the frontal light. On the E70, the front light sensor regulates the brightness of the Head Up Display.
- Solar sensor: consisting of 2 photo diodes that measure the intensity of the sunlight for the driver's and passenger's side.
- Electronic module: for evaluation of the sensor signals.
Requirements for faultless operation of the rain sensor are:
- No smear on the windscreen
- Sensor area free of soiling (salt, insects)
- Wiper blades OK
- Windscreen in the area of the rain sensor without faults (stone impact)
- Optical element bonded free of bubbles with the windshield glass

Brief description of components
The rain/light solar sensor is inserted from the inside of the windscreen in the wiper range of the windscreen wiper. The rain/light solar sensor is fixed in the bracket by a steel-plate spring. The holder is firmly bonded to the windscreen. There is a gel pad between the rain/light solar sensor and the windscreen. The gel pad is fitted on the optical element (new component). It provides the optical connection to the windscreen and prevents dirt from entering.

NB: after installation of a new rain/light solar sensor, the gel pad can no longer be removed without damage, rather it is destroyed.

Index:

This installation location ensures that the windscreen surface in the area of the sensor remains free of dirt and ice. To prevent the sensor surface from fogging over, the sensor is heated.
The rain driving light / solar sensor is supplied with voltage from the roof function centre. The signals of the rain / driving light / solar sensor are transferred through the data buses.

Rain sensor
The rain sensor is an optical sensor. It consists of an optical element. An electronic module is also integrated. Alongside the electronic evaluation unit, 3 optical transmitter and receiver diodes are integrated in the electronic module.
Driving light sensor
The driving light sensor is also an optical sensor. It consists of 2 photo diodes and the corresponding electronic evaluation unit. One photo diode is aligned forwards and it picks up the light that strikes the front (frontal light). The second diode is aligned upwards and it picks up the light striking from above (ambient light).
Solar sensor
The solar sensor consists of two photo diodes. These diodes are fitted on the right and left on the sensor field of the rain / driving light / solar sensor.
Electronic module
The electronic module evaluates the individual sensor signals and communicates with the roof function centre.

System Functions
The following system functions are described for the rain / driving light / solar sensor:
- Detection of precipitation
- Detection for driving lights
- Detection of the sunlight intensity

Detection of precipitation
Operating button on the wiper switch activates the rain sensor. When the rain sensor is active, the function LED on the wiper switch lights up in green.

First of all, one wipe cycle is run as visual feedback of the switching on. Then, the 3 transmit diodes emit infrared light that is routed via the optical element to the windscreen. If the windscreen is completely dry and clean, the infrared light is fully reflected to the 3 receiver diodes.

If there is water or dirt in the area of the optical element on the windscreen, the infrared light is refracted. This means that only part of the infrared light is reflected to the receiver diodes. The amount of reflected light is thus the measurement of the intensity of the precipitation in the area of the optical element. The electronic evaluation unit uses the missing amount of light to detect the degree of wetness on the windscreen. It sends a signal across the data bus. On the basis of this signal, it is assessed in the junction box electronics whether a wipe cycle is necessary.

The sensitivity of the rain sensor can be varied in 4 stages by means of a knurled wheel on the wiper/washer switch. Each operation of the knurled wheel towards �Increase sensitivity� (i.e. turning the knurled wheel upwards) runs a wipe cycle.

With the vehicle stationary and failure of the rain / driving light / solar sensor, the windscreen wiper is switched into a fixed intermittent operation mode. On switching off terminal R, the rain sensor is switched off for safety reasons.

Detection for driving lights
The change in lighting conditions in front of the vehicle and in the environment of the vehicle is picked up by the light-sensitive sensors. The lighting condition is processed by the electronic evaluation unit and sent across the data bus to the footwell module. Depending on the brightness, with the Automatic Light Control active, the low-beam headlight is switched on and off.

Detection of the sunlight intensity
The solar sensors measure the intensity of the sunlight separately for the driver's and passenger's side. The sensor data is processed in the electronic evaluation unit and sent across the data bus to the IHKA control module. The IHKA control module evaluates these sensor signals.

Notes for Service department
The following information is provided for service of the rain / driving light / solar sensor:

General information
A dry and undamaged windscreen surface is necessary for installation of the rain / driving light / solar sensor. Furthermore, the sensor must be bonded to the windscreen without bubbles.
For fault-free operation of the rain/light solar sensor, there may be no streaks on the windscreen. Moreover, the wiper blades must be OK.

Diagnosis instructions
Initialization of the rain sensor
In order to ensure perfect function of the optical measurement procedure for the detection of precipitation, the rain sensor must be adapted to the windscreen.
Requirement for faultless initialization is that the windscreen glass is dry, clean and free of defects in the area of the rain sensor.
The initialization is performed using the service function �Initialize rain sensor� in the BMW diagnosis system. In this service function, the adaptation values in the rain sensor are deleted.
A re-initialization of the rain sensor is required:
- After replacing the windshield
- After installation of a rain / driving light / solar sensor
Coding the rain/light solar sensor
Coding of the rain / driving light / solar sensor is required:
- After replacing the windshield
- After replacement of a rain/light solar sensor
At each new start, the junction box electronics (JBE) check whether the coding data stored in the rain/light solar sensor match the target coding data stored in the junction box electronics.
In the event of deviations, the junction box electronics run automatic coding in accordance with the target coding data.
The automatic driving lights control provides a coding possibility to change the sensitivity settings (Japanese version: changed sensitivity settings).

Restrictions due to factors inherent in the system
Rain sensor:
Soiling of the sensor surface can lead to unwanted triggering, up to and including continuous wiping. If the soiling continues over a longer period, the system reacts with a reduction in sensitivity.
Soiling can be caused by salt residues, insects or water smears. The windscreen should therefore be cleaned from time to time using the wipe-wash function.
As the window wiper cleans the sensor surface, the wiper must not be worn. A worn wiper would diminish the measured values of the sensor by smearing as the values are no longer able to change.
The formation of bubbles on the bonding surface of the optical element impairs the rain function

Light sensor:
Due to the high surrounding brightness, fog cannot be detected by the light sensor.
The light sensor is sensitive to light in the infrared range. The infrared proportion is high if there is dense cloud cover. With lighter cloud cover or blue sky - above all in winter - the sensor receives considerably fewer infrared light proportions. This means the light sensor switches the light on earlier or leaves it on for longer.
In well illuminated tunnel entrances, startup can be delayed. The high level of illumination means that the measured values are above the switch-on threshold.
The formation of bubbles on the bonding surface of the optical element impairs the lighting function.

No liability can be accepted for printing or other faults. Subject to changes of a technical nature.