Cabin light intensity: Notes

Fig 1: Identifying Cabin Light Intensity Communication Flow Line

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Fig 2: Cabin Light Intensity - Circuit Diagram

Courtesy of SAAB-SCANIA OF AMERICA, INC.

When the light intensity in the cabin exceeds a certain level, the SID sends out RHEOSTAT VALUE 0% on the bus.

To increase bulb life, the main instrument unit's control module then turns off the following instrument lighting:

• Speedometer
• Tachometer
• Coolant temperature gauge
• Fuel gauge
• Selector lever indicator (automatic transmission)

For better visibility, the brightness of the indicator and warning lamps is set to two different levels. Low brightness at night and high brightness during the day.

The SID transmits the cabin light intensity (in lux), and at a certain value, the main instrument unit control module changes the light intensity of the following lamps:

Common to all these lamps is that they are supplied with +15 current from the main instrument unit and grounded through its control module.

• Fuel level warning lamp
• INFO DISPL lamp
• Central warning lamp
• Rear fog light
• LH direction indicators
• RH direction indicators
• CRUISE
• SPORT
• WINTER
• Selector lever indicator (segment)

The brightness of the following lamps is changed between day and night in a similar way but they are all supplied with current from the component in question and grounded through the main instrument unit.

• Main beam
• Lights on