Lanos S Hatchback L4-1.6L DOHC D-TEC MFI (1999)
Sensing and Diagnostic Module (SDM): Description and Operation
The SDM:
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Has no user-serviceable parts.
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Is on the floor ahead of the front console assembly.
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Continuously monitors the system components.
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Records any faults which are discovered.
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Illuminates a warning lamp that alerts the driver to any faults.
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Allows the fault codes to be retrieved with a scan tool.
The SDM controls the deployment of the airbag system through the use of the:
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Arming sensor.
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Capacitor.
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Crash sensor or accelerometer.
Arming Sensor
The arming sensor is a safety device made up of a dual-contact, electro-mechanical switch that:
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Acts independently of the electronic components.
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Keeps the tiring circuits for the airbags unarmed under normal driving conditions.
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Allows the airbags to deploy under the required conditions.
Capacitor
The capacitor provides reserve power.
Crash Sensor
The crash sensor, or accelerometer, electronically represents the acceleration or deacceleration of the vehicle during a frontal impact. In this electronic
representation, the electrical signal is proportional to the acceleration or deceleration of the vehicle.
