Rear fog lights switch (161)
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Rear fog lights switch (161)
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Light switch unit (684), automatic headlamp levelling (AHL)
Used to activate the rear fog light. BCM sends button status on the bus.
The light switch has a button with return spring for the rear fog light. When the button is depressed, pin 5 is grounded. The button has an internal diagnostic resistor. When the button is not depressed, only the internal resistor (1.8 kΩ) is connected between the connection and ground. The light switch also has LEDs to illuminate the symbols and knob.
The light switch is directly grounded to the body. The rear fog light pin is fed separately via a resistor integrated in BCM. Voltage between the pin and ground will be 0 V when the circuit is closed to ground and approx. 6 V when it is open. If the control module reads 10.2 V, it will interpret it as a break. The LEDs are grounded internally and are supplied PWM from BCM.
Pin No.
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Signal type
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Description
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4
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Lighting
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From BCM. + supply with PWM to LEDs
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2
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Rear fog light
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To BCM. Grounded when the button is depressed
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1
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Ground
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Ground in the body
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