9-3 (9440) L4-2.0L Turbo (2.0 HOT) (2003)
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The switch is a unit consisting of a three-position knob for the headlamps, two spring-back buttons for front and rear fog lights, and LEDs to light the
symbols and knob. The switch also contains four diagnostic resistors. When the knob is all the way to the right (lights off), the switch's contacts open and
only two of the internal diagnostic resistors (1.8 kohm each) are linked between each connection and ground. If the knob is turned one click to the left
(parking lights), pin 2 is grounded. Another click to the left (headlamps) grounds pin 1. If the front fog light button is pressed, pin 4 is grounded, while
pin 5 is grounded if the rear fog light button is pressed. If no button is pressed and the knob is in its OFF position, only the four internal diagnostic
resistors (1.8 kohm each) will be linked between each connection and ground.
On cars without xenon lamps, there are three additional knob positions to the left of the headlamp position. These are used for headlamp levelling. They
are resistive multiplexing, which leads to an additional number of resistors in this variant. Five resistors are internally coupled between +15 and ground.
The switch knob straight up in the headlamp position gives normal beam length. High voltage is taken out in this position between the fourth and fifth
resistor calculated from ground. Each step the beam length is to be moved closer to the car, voltage is taken out closer to ground, thereby sinking.
Connection
The light switch is directly grounded to the body. The two pins of the lighting knob, the pin for front fog lights and the pin for rear fog light, are fed 10.2.
V separately via a 1.2 kohm resistor integrated in BCM (headlamp position has 1.5 kohm). Voltage between each pin and ground is 0 V when the circuit
is closed to ground and approx. 6 V when it is open (headlamp position 5.5 V). If the control module detects 10.2 V, it will be regarded as a break. The
LEDs are grounded internally and are supplied with PWM from BCM. Headlamp levelling requires one pin for +15 and one for the output to the two
headlamp levelling motors.
Pin No. 1 - 8
