Instrument and Display Lighting

The brightness of certain lamps in the main instrument display panel is controlled by the Saab Information Display (SID) unit via pins 3 and 4.

There are three different brightness levels:
- Rheostat level
- Cabin light level
- Display lighting level

Rheostat
The rheostat is connected to the SID unit which sends the rheostat value to pins 3 and 4 of the main instrument display panel.

The rheostat also controls the following instrument lighting when it is dark:
- Speedometer
- Tachometer
- Coolant temperature gauge
- Fuel gauge
- Turbo pressure gauge







Cabin light level
The light sensor is mounted in the SID unit which sends a light intensity signal to pins 3 and 4 of the main instrument display panel.

When light intensity exceeds a certain level, the following instrument lighting will be extinguished:
- Speedometer
- Tachometer
- Coolant temperature gauge
- Fuel gauge
- Turbo pressure gauge

Similarly, the brightness of the following indicator and warning lamps changes when the light intensity in the cabin drops below a certain level.

Low intensity in the dark and high intensity in daylight.

All these lamps are grounded in the main instrument display panel.
- LH direction indicators repeater
- RH direction indicators repeater
- Main beam
- Lights on
- Rear fog light
- CRUISE

The brightness of the following lamps also changes in daylight and in the dark but they all receive current (+15 circuit) from the main instrument display panel and are grounded in the main instrument display panel's control module:
- Fuel warning lamp
- INFO DISPL lamp
- Central warning lamp







Display lighting
The SID unit calculates a suitable display lighting intensity on the basis of the rheostat value and the light intensity in the cabin, which is obtained from the light sensor.

When it is dark, display lighting is controlled by the rheostat setting and as it gets lighter it is controlled by the light intensity in the cabin.

This ensures that the displays will be easy to read in all conditions of light

The following lamps are controlled by the intensity of the display lighting in the main instrument display panel:
- Trip meter
- Odometer