Canyon 2WD L5-3.5L VIN 6 (2004)
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
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 a stored value, the SDM will cause current to flow through the
appropriate deployment loops to deploy the air bags or pretensioners. 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.
