False failure detection prevention in an air bag diagnostic system

Claim 1

In an air bag restraint deployment system for an automotive vehicle including: a plurality of crash sensors mounted in the front of the vehicle, each having an electrical configuration of a normally open switch and being connected in parallel; a deceleration sensor mounted towards the rear of the vehicle and having the electrical configuration of a normally open switch; means connected in series between said crash sensors and said deceleration sensor for inflating said air bag in response to the concurrent closing of both said sensors; circuit means for supplying a system voltage across said interconnected deceleration sensor, inflation means and crash sensor; means for disarming said system by interrupting the circuit means and inhibiting said supply of system voltage across said deceleration sensor, inflation means and said crash sensor; means connected to said deceleration sensor, said crash sensors, said inflation means, and said disarming means, for monitoring their operating condition, for providing an indication when an operating condition is impaired, and for providing a disarmed signal to said disarming means when a short is detected across any of said crash sensors; an improvement comprising: means connected to a junction between said crash sensors and said inflation means, and to said disarming means to receive said disarm signal, and for responsively activating said disarming means only when a short is present across any of said crash sensors.