Instrument and display lighting: Notes

So that the main instrument unit gauges, lamps and displays will be easy to read in both daylight and at night, as well as to achieve optimum bulb life, the main instrument unit's control module regulates the lighting intensity of the display according to the brightness in the cabin and the rheostat setting selected by the driver.

The rheostat is connected to the SID where the light sensor is also mounted.

The SID continuously sends information about the following light values on the bus:

Fig 1: Instrument And Display Lighting Communication Diagram

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Fig 2: Instrument And Display Lighting Circuit Diagram

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Rheostat value, unit %.
Rheostat value Night Panel (this value is not used by the main instrument unit).
Light intensity in the cabin, unit Lux.
Display lighting, unit %.