Air Bag Terminology

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

ASYNCHRONOUS - The event can occur at any time. There is no defined time or interval for the event to occur within.

B+ - This represents the battery voltage available at the time of the indicated measurement. With the ignition switch in the RUN position and the engine not running, the voltage will likely be between 11.5 and 12.5 volts. At engine idle, the voltage may be 14 to 16 volts. The voltage could be as low as 10 volts during engine craning.

BULB TEST - The Instrument Panel Cluster (IPC) 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 (SDM) then commands the IPC to turn the warning lamp OFF through serial data communication. This indicates that there are no malfunctions in the SIR system. If a SIR system malfunction is present, the IPC flashes the warning lamp seven times and the inflatable restraint Sensing and Diagnostic Module (SDM) then commands the IPC to turn the warning lamp ON.

CONTINUOUS MONITORING TESTS - Tests performed by the inflatable restraint Sensing and Diagnostic Module (SDM) on the SIR system during each 100 millisecond interval. The IGNITION 1 voltage at the SDM must be within the normal operating voltage range for continuous monitoring to occur. These tests follow the Power-ON tests.

DATA LINK CONNECTOR (DLC) - The DLC connects to multiple on-board computers using wires. The DLC allows 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 of the vehicle. All vertical measurements originate from this baseline.

DEPLOY - To inflate the air bag.

DEPLOYMENT LOOP CONTINUITY TEST - Tests performed by the inflatable restraint Sensing and Diagnostic Module (SDM) that check voltage differences between the Driver Side High and LOW and the Passenger Side High and LOW circuits. First the SDM measures IGNITION 1 and 23 VLR in order to verify that they are within their respective normal voltage ranges. Then the SDM performs the DEPLOYMENT LOOP CONTINUITY test. Detection of a malfunction during these tests may prevent the RESISTANCE MEASUREMENT test from occurring until the next ignition cycle. This test is part of the POWER-ON tests and occurs before the CONTINUOUS MONITORING tests.

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

DIAGNOSTIC TROUBLE CODE (DTC) - An alphanumerical designator used by the inflatable restraint Sensing and Diagnostic Module (SDM) to indicate specific malfunctions.

DRIVER CURRENT SINK - An output of the inflatable restraint Sensing and Diagnostic Module (SDM) that 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 (SDM) that supplies current into the inflatable restraint steering wheel module circuit.

EEPROM - Electrically Erasable Programmable Read Only Memory. Memory that does not require power to the inflatable restraint Sensing and Diagnostic Module (SDM) in order to retain its contents.

HIGHER PRIORITY FAULT - Each diagnostic trouble code has an assigned priority based on its detectability with other DTCs present. The priority corresponds to the detectability of the malfunction ONLY. This does NOT relate to the criticality of the malfunction with respect to deployment or non-deployment under any given condition.

IGNITION CYCLE - An event caused by the operation of the ignition switch. First the inflatable restraint Sensing arid Diagnostic Module (SDM) must sense IGNITION 1 input greater than 7.8 volts with the ignition switch in the RUN position. Then this IGNITION 1 input must remain above 7.8 volts for at least ten seconds before turning the ignition switch to the OFF position.

IGNITION 1 - A battery voltage (B+) circuit receiving power with the ignition switch in the RUN, or START positions.

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

INFLATABLE RESTRAINT SENSING AND DIAGNOSTIC MODULE (SDM) -The inflatable restraint Sensing and Diagnostic Module (SDM) that provides 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 MODULE COIL - An assembly of two or more current-carrying coils mounted within the steering column hub, The assembly allows the rotation of the steering wheel while maintaining the continuous electrical circuit contact. Two of the coils provide 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 (SDM) Ignition 1 terminal and Ground terminal is between 7.8 and 18.0 volts.

PASSENGER CURRENT SINK - An output of the inflatable restraint Sensing and Diagnostic Module (SDM) which supplies a low resistance path to ground for the inflatable restraint I/P module circuit.

PASSENGER CURRENT SOURCE - An output of the inflatable restraint Sensing and Diagnostic Module (SDM) which supplies current into the inflatable restraint I/P module circuit.

RESISTANCE MEASUREMENT TESTS - Is performed by the inflatable restraint Sensing and Diagnostic Module (SDM) 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 m the SIR system.

STATE OF HEALTH (SOH) DTCs - Diagnostic Trouble Codes set by any module communicating on the Serial Data Line Class 2 that indicate Serial Data Line Class 2 faults.

POWER-ON TESTS - Test which the inflatable restraint Sensing and Diagnostic Module (SDM) 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 (SDM) 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 (SDM).