Leganza SX L4-2.2L DOHC D-TEC MFI (1999)
Sensing and Diagnostic Module (SDM): Description and Operation
CAUTION: During service procedures, be careful when handling the sensing and diagnostic module (SDM). Never shake or jar the SDM. Never apply
power to the supplemental inflatable restraints (SIR) system when the SDM is not rigidly attached to the vehicle. All SDM mounting bolts must be fully
tightened. The arrow on the SDM must point toward the front of the vehicle. Failure to follow these precautions could cause deployment and result in
personal injury.
The SDM is located on the floor beneath the floor console assembly. The SDM performs the following functions:
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Monitors the SIR system electrical components and sets a diagnostic trouble code (DTC) when a malfunction is detected.
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Records any faults that are discovered.
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Displays SIR DTCs and system status information when connected to a scan tool.
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Illuminates the AIRBAG indicator to alert the driver to any faults.
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Provides a reserve power source to deploy the airbags if an accident has disabled the normal power source.
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Monitors vehicle velocity changes to detect frontal impacts which are severe enough to warrant deployment.
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Causes current to flow through the airbag modules to cause deployment if the SDM detects a frontal impact of sufficient force.
The SDM contains no user-serviceable parts.
