9000 Hatchback L4-2290cc 2.3L DOHC Turbo EFI (1994)
Solar Sensor: Description and Operation
Sun Load Sensor (Solar Sensor)
It registers solar intensity but also height and azimuth through the windscreen. Solar height is measured between 0° (horizontally) and 90°
(vertically). The azimuth reading covers 360°, where 0° is directly forwards, 90° directly to the right etc.
The solar sensor transmits a series of pulses back to the ACC control module. These series of pulses are then processed in the control module's
microprocessor.
The solar sensor consists of five solar cells which are soldered to a circuit board which is in turn encased in a plastic box filled with silicone. In
earlier models, the microprocessor was also encased with the sensor. The electronics are now located in the ACC control module.
The sensor is enclosed in a cover of non-scratch plastic. The top side of this cover also functions as a filter and only transmits infrared radiation.
The signal which corresponds to the intensity of solar radiation ranges between 0-1390 W/m squared.
The fact that the solar sensor primarily measures heat radiation means that it cannot be tested using a fluorescent tube. Sunlight or an incandescent
lamp must be used.
If there is no data from the solar sensor, a default value of 0 is used.
