Air Bag Terminology

AIR BAG - An inflatable cloth cushion designed to deploy in certain frontal crashes. It supplements the protection offered by the seat belt by distributing the impact load more evenly over the occupant's head and torso.

B+ - Battery voltage, the voltage available at the battery at the time of the indicated measurement. With the key "On" and the engine not running, the system voltage will likely be between 12 and 12.5 volts. At idle the voltage may be 14 to 16 volts. The voltage could be as low as 10 volts during engine cranking.

BULB CHECK - The seven flashes of the Air Bag Telltale whenever the ignition switch transitions from "Off" to "Run or Start." If no SIR malfunctions are detected the air bag telltale will remian "Off" during normal vehicle operation.

COIL ASSEMBLY - An assembly of current-carrying coils (two for SIR) in the driver deployment loop that allows the rotation of the steering wheel while maintaining the continuous contact of the driver deployment loop to the driver inflator module.

CONTINUOUS MONITORING - Tests performed by the SDM on the SIR system every 100 milliseconds while "Ignition 1" voltage is present at the SDM.

CURRENT CODES - Current DTCs are malfunctions that are presently being detected.

CURRENT SOURCE DIAGNOSTICS - Tests performed by the SDM after ignition 36 VLR, and deployment loop voltages are all measured within their respective normal voltage ranges. This test checks for proper resistance of the deployment loops and for proper operation of the driver and passenger current sources.

DATA LINK CONNECTOR (DLC) - Connector which is connected by wires to multiple on-board computers allowing communication with an off-board computer such as a scan tool.

DEPLOY - To inflate the air bag.

DEPLOYMENT LOOP - The circuits which supplies current to the inflator module to deploy the air bag.

DIAGNOSTIC TROUBLE CODE (DTC) - An alpha numerical designator used by the SDM to indicate specific SIR system malfunctions.

DRIVER INFLATOR MODULE - An assembly located in the steering wheel hub consisting of an inflatable bag, an inflator and an initiator.

EEPROM - Electrically erasable programmable read only memory. Memory which retains its contents when power is removed from the SDM.

HIGHER PRIORITY FAULT - Each diagnostic fault code is assigned a priority based on the detectability with other codes present. The priority corresponds to the detectability of the malfunction only, and does not relate to the criticality of the malfunction with respect to deployment or non-deployment under any given condition.

HISTORY CODES - History DTCs are malfunctions detected since last clearing of the SDM memory. History DTCs are stored in the SDM's memory, most history DTCs can be cleared using the Scan tool. Some history DTCs are latched and cannot be cleared.

IGNITION CYCLE - The voltage at the SDM "Ignition 1" input, with ignition switch "On," is greater than nine volts for at least ten seconds before turning ignition switch "Off."

IGNITION 1 - A battery positive (B+) circuit which is only powered with the ignition switch in the RUN or START position.

INITIATOR - The electrical component inside the inflator module which, with sufficient current flow, starts the chemical reaction that inflates the air bag.

NORMAL OPERATING VOLTAGE RANGE - The voltage measured between the SDM "Ignition 1" terminal and ground is between 9 and 16 volts.

PASSENGER INFLATOR MODULE - An assembly located in the left side of the instrument panel consisting of an inflatable bag, an inflator and an initiator.

PORTABLE SCAN TOOL - An off-board computer used to read diagnostic information from on-board computers via data link connector.

SDM - Sensing and diagnostic module which provides reserve energy to the deployment loops, deploys the air bag when required and performs diagnostic monitoring of all system components.

SERIAL DATA - Information representing the status of the queried system.

SIR - Supplemental Inflatable Restraint.

SIR WIRING HARNESS - The wires and connectors that electrically connect the components in the SIR system.

TURN-ON-TESTS - Tests which the SDM performs on the SIR system once during each ignition cycle immediately after Ignition 1 voltage is applied to the SDM and before "Continuous Monitoring."

VLR DELAY (volt loop reserve) - Charging of the VLR power supply is inhibited briefly during "TURN-ON." This allows detection of certain malfunctions related to "Ignition 1" voltage which cannot be tested with approximately 23 volts present.