9-3 (9440) L4-2.0L Turbo (2.0 HOT) (2003)
Remote Switch: Description and Operation
Switch unit, steering wheel (633)
Location
Switch unit, steering wheel (633)
Main use
Operating audio and telephone systems, changing gear up and down on automatic transmission cars.
Type
For the audio and telephone functions, the switch has 8 contacts that act on 8 series-connected resistors with varying values. Pressing the button will
ground the associated contact. There is an additional resistor for diagnosing these functions. For changing gear up and down, there are 2 contacts and
3 resistors, one each for changing up and down and one for diagnosis. Depending on the switch being pressed, the aggregate resistance will change
and thereby the voltage. The buttons have integrated LEDs so that the symbols are visible in the dark.
Activation
The steering column control module supplies 5V to the switch for audio and telephone on pin 1 and for Sentronic on pin 4 with ground on pin 2. Pin 3
is supplied with 12 volts for the LEDs, which are also grounded via pin 2. Depending on the switch pressed, the aggregate resistance will change and
thereby also the voltage.
Wiring diagram, power supply