Definitions/Abbreviations

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 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 DERM will cause the "INFLATABLE RESTRAINT" warning lamp to flash 7 times and then go "OFF" whenever the ignition switch transitions to the RUN position from any other ignition switch position and no malfunctions are detected.

CONTINUOUS MONITORING - Tests performed by the DERM on the SIR system every 100 milliseconds while "Ignition 1" voltage is in the normal operating voltage range at the DERM.

DATA LINK CONNECTOR (DLC) - Formerly "ALDL," 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 - The circuits which supply current to the inflator modules to deploy the air bags.

DERM - Diagnostic Energy Reserve Module which provides reserve energy to the Deployment Loops and performs diagnostic monitoring of all SIR system components.

DIAGNOSTIC TROUBLE CODE (DTC) - Formerly referred to as "Code," a numerical designator used by the DERM to indicate specific SIR system malfunctions.

DISCRIMINATING SENSOR - A sensor on the low side (ground side) of the Deployment Loops which is calibrated to supply ground to the inflator modules when the vehicle velocity changes are sever enough to warrant deployment of the air bags.

DRIVER CURRENT SOURCE - An output of the DERM which injects current into the Driver Inflator Module Circuit during the "Initiator Assembly Resistance Test."

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

DUAL POLE ARMING SENSOR - A sensor connected to the high side (power side) of the Deployment Loops which is calibrated to supply voltage to the inflator modules when the vehicle velocity changes are severe enough to warrant arming of the air bags in preparation for deployment.

EEPROM - Electrically Erasable Programmable Read Only Memory. Memory which retains its contents when power is removed from the DERM.

HIGHER PRIORITY FAULT - Each Diagnostic Trouble Code (DTC) is assigned a priority base 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 DERM "Ignition 1" inputs, with the ignition switch "ON," is within the normal operating voltage range for at least 10 seconds before turning the ignition "OFF."

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

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

INITIATOR ASSEMBLY RESISTANCE TEST - Tests performed once each ignition cycle when no malfunctions are detected during "Turn-ON" or "Continuous Monitoring." This test checks for the correct DERM configuration for the vehicle, shorts to "Ignition 1" in the deployment loops, high resistance or opens in the "Driver Side High," "Driver Side Low," Passenger Side High" and Passenger Side Low" circuits and measures the resistance of the inflator assembly consisting of: 1) Initiators, 2) SIR coil assembly (driver side only), 3) Connectors and associated wiring.

NORMAL OPERATING VOLTAGE IGNITION 1 RANGE - The voltage measure between the DERM "Ignition 1" terminals and "Ground" terminals is between 7.25 and 16 volts.

PASSENGER CURRENT SOURCE - An output of the DERM which injects current into the Passenger Inflator Module circuit during the "Initiator Assembly Resistance Test."

PASSENGER INFLATOR MODULE - An assembly located in the right side of the I/P beneath the I/P trim pad consisting of an inflatable bag, an inflator and an initiator.

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 COIL ASSEMBLY - 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 Driver Inflator Module.

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

10 MINUTE LOOP TEST - Portions of the "Initiator Assembly Resistance Test" are repeated every 10 minutes during an ignition cycle. These are the check for shorts to "Ignition 1" in the Deployment Loops and the check for an open Discriminating Sensor Interconnect Circuit.

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

36 VLR - The 36 Volt Loop Reserve energy supplies from the DERM which provide deployment power when vehicle voltage is low or lost in a frontal crash.

36 VLR DELAY - Charging of the 36 VLR power supplies is inhibited briefly during "Turn-ON." This allows detection of certain malfunctions related to "Ignition 1" voltage which cannot be tested with 36 volts present.