Patent ID: 7739012

Claim:
An air bag system which is equipped with first and second acceleration sensors for detecting a vehicle crash, and which outputs a signal for expanding an air bag when it is determined that a vehicle crash has occurred based on outputs of said first and second acceleration sensors, said air bag system comprising: a microcomputer comprising: a crash determination section for making a crash determination by processing the output signal of said first acceleration sensor; and a fault diagnosis section for diagnosing operation faults in said first acceleration sensor and said crash determination section; and an integrated circuit comprising: a safing determination section for making a safing determination by processing an output signal from said second acceleration sensor; an erroneous-activation fault diagnosis section which, based on an output signal generated by activating said second acceleration sensor with a pseudo crash signal from said microcomputer, checks for the presence of an erroneous-activation fault in which, in a situation where said air bag is not to be expanded, said second acceleration sensor outputs a signal that is contradictory to said situation; and an output circuit for outputting an airbag firing signal based on a crash signal from said microcomputer and a signal from said safing determination section; said microcomputer further comprising a non-activation fault diagnosis section which, based on an output signal generated by activating said second acceleration sensor with said pseudo crash signal from said microcomputer, checks for the presence of a non-activation fault in which, in a situation where said air bag is to be expanded, said second acceleration sensor outputs a signal that is contradictory to said situation.