Trw Limited

Jeffrey R Rochette

Edward J Abeska

Roger A McCurdy

Dana A Stonerook

Richard J Mann

A method and apparatus are disclosed for testing an airbag restraint system of the type having at least two parallel connected inertia sensors connected in series with a squib across a source of electrical energy, each inertia sensor having a normally open switch and an associated parallel connected resistor. Each parallel connected inertia sensor has a series connected diode for isolating its associated inertia sensor circuit from other circuit components in the firing circuit. A microcontroller monitors at least one voltage value at a component connection while at least one parallel connected inertia sensor is isolated. The microcontroller determines a value functionally related to the resistance of at least one circuit component in the firing circuit while at least one parallel connected inertia sensor is isolated. The microcontroller compares the determined value against predetermined limits. If the determined value is not within the predetermined limits, an error indication is provided.

Method and apparatus for testing an airbag restraint system with

A test circuit for an airbag restraint system is disclosed and provides an accurate determination of the operativeness of a storage capacitor and calculates the resistance of inertia switch resistors. The capacitor is tested by discharging and charging the capacitor. The values of the inertia switch resistors are determined by switching known resistive values in parallel with the inertia switch resistors. Based on the monitored voltage values during the switching, resistance values are calculated.

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Livonia, MI, United States of America

Jeffrey R Rochette