DeVille DHS V8-4.6L VIN Y (2000)
Inflatable Restraint Sensing and Diagnostic Module: Description and Operation
General Information
IMPORTANT: In order to prevent accidental deployment, shorting bars close in order to short the terminals when the connectors are separated.
Frontal SIR System Description
The frontal SIR system consists of the following components:
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An inflatable restraint Sensing and Diagnostic Module (SDM).
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An inflatable restraint steering wheel module (steering wheel air bag).
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An Inflatable restraint steering wheel module coil.
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An inflatable restraint IP Module (IP air bag). An driver seat belt pretensioner
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An passenger seat belt pretensioner
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An AIR BAG Warning Lamp in the Instrument Panel Cluster (IPC).
The inflatable restraint sensing and diagnostic module (SDM), inflatable restraint steering wheel module coil, inflatable restraint steering wheel module,
inflatable restraint IP module, driver seat belt pretensioner, passenger seat belt pretensioner, and the connecting wires make up the frontal deployment
loops. The function of the frontal deployment loops is to supply current through the frontal inflator modules, deploying the frontal inflator modules
simultaneously. Deployment occurs when the SDM detects vehicle velocity changes severe enough to warrant deployment.
The SDM contains a sensing device (accelerometer) that converts vehicle velocity changes to an electrical signal. The SDM compares this electrical
signal to a value stored in memory. When the generated signal exceeds the stored value, the SDM performs additional signal processing and compares
the generates signals to values stored in memory. When two of the generated signals exceed the stored values, the SDM will cause current to flow
through the frontal inflator modules deploying the frontal inflator modules.
Inflatable Restraint Sensing and Diagnostic Module
The inflatable restraint Sensing and Diagnostic Module (SDM) performs the following functions in the SIR system:
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Energy Reserve - The SDM maintains 23 Volt Loop Reserve (23VLR) energy supplies to provide deployment energy. Ignition voltage can
provide deployment energy if the 23 Volt Loop Reserves malfunction.
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Frontal Crash Detection - The SDM monitors vehicle velocity changes to detect frontal crashes that are severe enough to warrant deployment.
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Frontal Air Bag Deployment - During a frontal crash of sufficient force, the SDM will cause enough current to flow through the frontal inflator
modules to deploy the frontal air bags.
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Frontal Crash Recording - The SDM records information regarding the SIR system status during a frontal crash.
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Side Impact Crash Detection - The SDM communicates with both inflatable restraint Side Impact Sensors (SIS) and monitors the vehicle side
accelerations/decelerations to determine if during a side crash event side air bag protection are needed for Driver and/or Passenger.
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Side Air Bag Deployment - During a side impact crash of sufficient force, the SDM will cause enough current to flow through the side inflator
modules to deploy the side air bags.
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Side Impact Crash Recording - The SDM records information regarding the SIR system status during a side impact crash.
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Rear Side Impact Crash Detection - The SDM communicates with both inflatable restraint side impact sensors (SIS) and monitors the vehicle side
accelerations/decelerations to determine it during a side crash event side air bag protection are needed for Driver and/or Passenger.
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Rear Side Air Bag Deployment - During a side impact crash of sufficient force, the SDM will cause enough current to flow through the side
inflator modules to deploy the side air bags.
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Rear Side Impact Crash Recording - The SDM records information regarding the SIR system status during a side impact crash.
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Malfunction Detection - The SDM performs diagnostic monitoring of the SIR system electrical components. Upon detection of a circuit
malfunction, the SDM will set a Diagnostic Trouble Code (DTC).
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Malfunction Diagnosis-The SDM displays SIR Diagnostic Trouble Codes (DTC) and system status information through the use of a scan tool.
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Driver Notification - The SDM warns the vehicle driver of SIR system malfunctions by controlling the AIR BAG warning indicator.
The SDM sends a message over the class 2 serial data line requesting to turn on the AIR BAG warning indicator.
The SDM connects to the SIR wiring harness using a 34-way connector.
The SDM receives power whenever the ignition is ON.
Rear Side Impact Air Bag System Description (Option AW9)
The rear side impact air bag system is made up of some components that are use in the side impact air bag system. The rear side impact air bag system
consists of the following components:
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Two Inflatable Restraint Side Impact Sensors (SIS) (one in each lower center pillar).
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Two inflatable restraint rear side impact inflator modules (one rear side air bag in back of rear seat).
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An inflatable restraint Sensing and Diagnostic Module (SDM).
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An AIR BAG Warning Lamp in the Instrument Panel Cluster (IPC).
The inflatable restraint side impact sensor (SIS), inflatable restraint rear side impact inflator modules (Rear Side Air Bags), inflatable restraint Sensing
and Diagnostic Module (SDM), and the connecting wires make up the rear side impact inflatable restraint system. The SDM contains a sensing device
(accelerometer) that converts vehicle velocity changes to an electrical signal. The SIS is treated as a discriminating sensor and is a input to the SDM. If
the SIS determines that the side air bags should be deployed, the SIS tells the SDM to deploy the front and rear side air bags. The SDM will then check
to see if there is enough vehicle acceleration to warrant a deployment. If so, the SDM will send current to the front and rear side air bags. Deployment
occurs when the SDM receive vehicle velocity changes through the SIS that are severe enough to warrant deployment.
