Display lighting: Notes
WARNING: This page is about a different car, the 2006 Saab 9-5. However, it is still accessible from the selected car via links, so may be relevant.
The SID control module calculates an appropriate value for the information display illumination using the rheostat value and the value of the cabin light intensity which comes from the light sensor.
When it is dark, the lighting is controlled by the rheostat value and when the light in the cabin increases it is controlled by the value of the light intensity in the cabin. This ensures that the odometer display will be easy to read in all lighting conditions.
The SID control module sends the calculated value to the bus as a Display lighting value, unit %.
The main instrument unit control module uses the value to control the information display illumination.