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Lighting for buttons and controls

Lighting for buttons and controls

The intensity of the button and control lighting can be varied with a rheostat on the dashboard to the left of the steering column. DICE receives information from SID (Saab Information Display) via the bus (RHEOSTAT READING) as to the desired value of the lighting rheostat. To calculate the correct rheostat value, SID uses a proportional value between a built-in resistor and the rheostat. SID sends the rheostat value (0-100%) to the bus. The value depends on the setting of the rheostat and the value of the cabin light sensor.

If DICE does not receive rheostat data via the bus when the ignition is switched on, the rheostat reading is set to 71%.

If the rheostat reading suddenly disappears during normal functioning, DICE uses the last reading taken until it once again receives updated information via the bus.

If the Night Panel mode is activated, DICE uses the NIGHT PANEL bus information instead of the RHEOSTAT READING. The button-and-control lighting assumes its Night Panel level, meaning that its intensity is reduced by a fixed amount.



Rheostat reading 0% (extinguished) is sent if:


• The main light switch is in the OFF position.

• The interior light exceeds a certain level.


The rheostat (16) is connected to SID (541) on pins 21 and 8. The information is sent to the bus from SID pins 24 and 12. The bus is connected to DICE pins 5 and 14.

DICE is powered to pin 24 with +30 via fuse 8. From pin 49 DICE powers the button-and-control lighting with a pulse-width-modulated voltage (about 100 Hz) from pin 49 to buttons and controls (10, 25, 375, 252D, 252P, 148F, 148R, 267a, 506, 91, 282, 88, 503, 504, 449, 615D, 615P, 386, 514A).

Diagnosis

The output is provided with overload protection which shuts it off in the vent of an excessive load. When this occurs, diagnostic trouble code B1735 will be generated.

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

Note

DTC B1736 will be generated if there is a break in the rheostat circuit, see .