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Solar sensor

Solar sensor





The solar sensor is situated on the top of the dashboard and contains 5 infrared-sensitive elements: left, right, front, rear and top. It is supplied with B+ pulses from pin 16 and is grounded from pin 36. Voltage from the 5 sensor elements is sent consecutively to pin 17 on the ACC unit.

For the control module to be able to detect which sensor element is reporting, the transmission is preceded by the pulse pattern 5 V – 0 V – 5 V. The control module synchronizes the solar sensor pulse transmission by sending short ground pulses at 25 Hz from pin 16.

With the voltage from the 5 sensor elements, the control module calculates the solar intensity, azimuth and height.

The values are used to calculate the current temperature at head height for the front seat passenger and driver. The following are also used as default values:


• outside temperature

• time since engine last ran

• time since start

• mixed-air temperatures

• fan speed


The calculated temperatures are compared to those the driver and passengers have set on the ACC unit display. The set temperature is adjusted with respect to the outside temperature so that the perceived temperature corresponds with the set temperature.

As soon as a difference occurs, the mixed-air temperature must be increased or decreased. The control module turns the air-mixing flap in question until the required mixed-air temperature is achieved.

Adjustment

Using the diagnostics tool, the ACC unit can be adjusted to include a larger or smaller proportion of the solar sensor value when calculating the cabin temperature.

Diagnostics

In the event of an open circuit or short circuit, diagnostic trouble code B1340 is set and 03 is displayed instead of right-hand temperature when calibrating. The latest valid value is used as a default value. When the ignition is turned on, 0 W/m 2 is used.