Air Bag Terminology

Air Bag: An inflatable cloth cushion designed to deploy in certain frontal crashes. The air bags distribute the impact load more evenly over the occupant's head and torso in order to supplement the safety belt protection.

Asynchronous: An event that may occur at any time without a warning and without falling within a defined time period.

B+: The battery voltage available at the time of the indicated measurement. With the ignition switch in the RUN position and the engine stopped, the voltage is usually 11.5-12.5 volts. With the engine at idle, the voltage may be 14.0-16.0 volts. During engine cranking, the voltage may be as low as 10.0 volts.

Bulb Test: The inflatable restraint sensing and diagnostic module (SDM) will cause the air bag warning indicator to flash 7 times. Under normal operation, this occurs when the ignition is turned from the OFF position to the RUN position. The bulb test will also occur it the IGNITION 1 voltage exceeds 17.1 volts and then returns within the normal operating voltage range. A malfunction could prevent the module from flashing the indicator.

Resistance Measurement Test: A test that the inflatable restraint sensing and diagnostic module (SDM) performs once per ignition cycle in order to measure the resistance of the deployment loops. The module first measures IGNITION 1, 23 VLR, and the deployment loop voltages in order to verify readings within specifications. The module then sources a constant current into the loop. The module measures the voltage drop across the loop and converts the value to a resistance value. This resistance value is within the range of 0.0-6.3 ohms. Upon the detection of an open circuit, the module aborts the tests in order to prevent the calculation of the resistances until the next ignition cycle. This test also inspects for proper operation of the driver/passenger current sources. This test is part of the power-on tests and occurs before the continuous monitoring tests.

Scan Tool: An off-board computer that reads on-board computer diagnostic information through the use of a DLC.

Serial Data: The information communicated to an off-board computer using the DLC. Some of this data represents 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. 23 VLR: The 23 volt loop reserve. The energy supply that is internal to the inflatable restraint sensing and diagnostic module (SDM).