900 SE Convertible V6-2498cc 2.5L DOHC (1995)
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When the engine hood is closed, the voltage between the switch and ground should be 12 V.
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When the hood is opened, the switch is grounded. The voltage between the switch and ground is thus 0 V. The alarm is set off.
Glass Breakage Sensor
The sensor is sensitive to sound (microphone) and senses if any of the windows is broken. It is integrated in the interior lighting lamp in the roof
(Cabriolet: beside the rear-view mirror) and connected to the control module via pin 7 (signal) and pin 5 (ground). The separate ground input for the
sensor has a filtering effect in order to avoid potential differences between the control module main ground and the sensor ground input.
When the theft alarm is armed and a window is broken, the sensor sends and analogue signal to the control module to set off the alarm. There is also a
button beside the sensor for manual disconnection of the glass breakage sensor. When the disconnection button is pressed disconnection happens through
the control module sensing a change in the signal level.
