Air Bag Control Module: Description and Operation

Sensing and Diagnostic Module (SDM)

WARNING: During the service procedures, be careful when handling the SDM. Never shake or jar the SDM. Never apply power to SIR when the SDM is not rigidly attached to the vehicle. All SDM mounting bolts and grounding nuts must be fully tightened. 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:
^ Monitors the supplemental inflatable restraints(SIR) electrical components and sets a diagnostic trouble code(DTC) when malfunction is detected.
^ Records any faults that are discovered.
^ Displays SIR diagnostic trouble codes and system status information when connected to a scan tool.
^ Illuminates the airbag indicator to alert the driver to any fault.
^ Provides a reserve power source to deploy the airbags and pretensioners if an accident has disabled the normal power source.
^ Monitors vehicle velocity changes to detect frontal impacts, which are severe enough to warrant deployment.
^ Causes current to flow through the airbag modules and pretensioner to cause deployment if a frontal impact of sufficient force is detected. The SDM contains no user-serviceable parts.