Malibu V6-3.1L VIN J (2002)
Impact Sensor: Description and Operation
INFLATABLE RESTRAINT SENSING AND DIAGNOSTIC MODULE (SDM)
The SDM is a microprocessor and the control center for the SIR system. In the event of a collision, the SDM performs calculations using the signals
received from the internal sensors and compares the results of the calculations to values stored in memory. When these calculations 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 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. In the event that Ignition 1 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 to note, when disabling the SIR system for servicing or rescue operations to allow the 23 VLR to dissipate, which could
take up to one minute.
