CTS V6-3.2L VIN N (2003)
Inflatable Restraint Sensing And Diagnostic Module: Description and Operation
INFLATABLE RESTRAINT SENSING AND DIAGNOSTIC MODULE (SDM)
The Sensing And Diagnostic Module SDM is a microprocessor and the control center for the SIR system. The SDM contains internal sensors along
with several external sensors, if equipped, mounted at strategic locations on the vehicle. In the event of a collision, the SDM compares the signals
from the internal and external sensors to a value stored in memory. When the generated signals exceed the stored value, the SDM will cause current to
flow through the appropriate deployment loops to deploy the air bags. The SDM records the SIR system status when a deployment occurs and turns
the AIR BAG indicator located in the IPC ON. The SDM performs continuous diagnostic monitoring of the SIR system electrical components and
circuitry when the ignition is turned ON. If the SDM detects a malfunction, a DTC will be stored and the SDM will command the AIR BAG indicator
ON, notifying the driver that a malfunction exist. In the event that ignition positive voltage is lost during a collision, the SDM maintains a 23-volt loop
reserve (23 VLR) for deployment of the air bags. It is important when disabling the SIR system for servicing or rescue operations to allow the 23 VLR
to dissipate, which could take up to 1 minute.
