SAAB WIS ONLINE

Lighting for buttons and controls

Lighting for buttons and controls

The intensity of the lighting for buttons and controls can be adjusted with a potentiometer on the dashboard to the left of the steering wheel. DICE obtains information from SID (Saab Information Display) via the bus (RHEOSTAT VALUE) about the desired light intensity. To calculate the correct rheostat value, SID uses a proportional value between an integral resistor and the rheostat. SID sends the rheostat value (0-100%) out on the bus. The value depends on the potentiometer setting and the cabin light sensor value.

If DICE receives no rheostat information via the bus when the ignition is switched on, the rheostat value is set to 71%.

If the rheostat value suddenly disappears during normal functioning, DICE freezes the current value until information is again available on the instrument bus.

If the Night Panel function is activated, DICE uses the NIGHT PANEL bus information instead of the RHEOSTAT VALUE. The lighting for buttons and controls switches to Night Panel, i.e. the light intensity is reduced by a fixed value.

The rheostat value 0% (off) is sent when:


• The main lighting switch is in the OFF position

• The interior light exceeds a certain level.




The potentiometer (16) is connected to SID (541) on pins 11 and 4. SID outputs information to the bus via pins 9 and 16. The bus is connected to DICE by pins 5 and 14.

Power +30 voltage is supplied to DICE pin 24 via fuse 4. DICE powers the lighting for buttons and controls from pin 49 with a pulse width modulated voltage (approx. 100 Hz) from pin 49 to the buttons and controls (10, 25, 88, 252D, 252P, 148F, 161, 537, 267a, 375, 503, 282, 254 and 386).

Diagnosis

The output has an overload protection that shuts the output off if the load is too high. This activates DTC B1735.

DTCs are not generated if the voltage is below 11V or during diagnostic communication.

Note

In the event of a break in the rheostat circuit, diagnostic trouble code B1736 is generated