Air Bag Terminology

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

ASYNCHRONOUS - Performed in a non-periodic fashion, i.e. no defined time or interval.

B+ - Battery voltage, the voltage available at the battery at the time of the indicated measurement. With the key to RUN 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 TEST - The instrument panel cluster will flash the AIR BAG warning lamp seven times when the ignition switch is turned from OFF to RUN. The inflatable restraint sensing and diagnostic module then commands the instrument panel cluster to turn the warning lamp OFF through serial data communication. This indicates that there are no malfunctions in the SIR system.

CONTINUOUS MONITORING TESTS - Tests performed by the inflatable restraint sensing and diagnostic module on the SIR system every 100 milliseconds while Ignition 1 voltage is in the normal operating voltage range at the inflatable restraint sensing and diagnostic module.

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

DATUM LINE - A base line parallel to the plane of the underbody or frame from which all vertical measurements originate.

DEPLOY - To inflate the air bag.

DEPLOYMENT LOOP CONTINUITY - Test is performed by the inflatable restraint sensing and diagnostic module after Ignition 1 and 23 VLR are measured within their respective normal voltage ranges. This test checks voltage differences between Driver Side High/Low and Passenger Side High/Low circuits.

DEPLOYMENT LOOPS - The circuits which supply current to the inflator modules to deploy the air bags.

DIAGNOSTIC TROUBLE CODE (DTC) - An alpha-numerical designator used by the inflatable restraint sensing and diagnostic module to indicate specific SIR system malfunctions.

DRIVE CURRENT SINK - An output of the inflatable restraint sensing and diagnostic module which supplies a low resistance path to ground for the inflatable restraint steering wheel module circuit.

DRIVER CURRENT SOURCE - An output of the inflatable restraint sensing and diagnostic module which supplies current into the inflatable restraint steering wheel module circuit.

EEPROM - Electrically Erasable Programmable Read Only Memory Memory which retains its contents when power is removed from the inflatable restraint sensing and diagnostic module.

HIGHER PRIORITY FAULT - Each diagnostic trouble code is assigned a priority based on the detectability with other DTCs 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.

IGNITION CYCLE - The voltage at the inflatable restraint sensing and diagnostic module Ignition 1 input, with ignition switch to RUN, is greater than 8.2 volts for at least ten seconds before turning ignition switch OFF.

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

INFLATABLE RESTRAINT I/P MODULE - An assembly located in the right side of the lip consisting of an inflatable bag, an inflator and an initiator.

INFLATABLE RESTRAINT SENSING AND DIAGNOSTIC MODULE - The inflatable restraint sensing and diagnostic module provides the reserve energy to the deployment loops, deploys the air bags when required and performs diagnostic monitoring of all SIR system components.

INFLATABLE RESTRAINT STEERING WHEEL COIL - An assembly of two current-carrying coils 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 inflatable restraint steering wheel module.

INFLATABLE RESTRAINT STEERING WHEEL MODULE - An assembly located in the steering wheel hub consisting of an inflatable bag, an inflator and an initiator.

INITIATOR - The electrical component inside the inflator module which, when sufficient current flows, sets off the chemical reaction that inflates the air bag.

NORMAL OPERATING VOLTAGE RANGE - The voltage measured between the inflatable restraint sensing and diagnostic module Ignition 1 terminal and Ground terminal is between 8.2 and 17.2 volts.

PASSENGER CURRENT SINK - An output of the inflatable restraint sensing and diagnostic module which supplies a low resistance path to ground for the inflatable restraint lip module circuit.

PASSENGER CURRENT SOURCE - An output of the inflatable restraint sensing and diagnostic module which supplies current into the inflatable restraint lip module circuit.

RESISTANCE MEASUREMENT TEST - Is performed by the inflatable restraint sensing and diagnostic module after Ignition 1, 23 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. If an open is detected this test is aborted before resistances are calculated, however, should the open clear the test will be completed meaning resistances will be checked.

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

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

SIR - Supplemental Inflatable Restraint.

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

TURN-ON TESTS - Test which the inflatable restraint sensing and diagnostic module performs on the SIR system once during each ignition cycle immediately after Ignition 1 voltage is applied to the inflatable restraint sensing and diagnostic module and before Continuous Monitoring.

23 VLR - The 23 volt loop reserve. This is an energy supply internal to the inflatable restraint sensing and diagnostic module.