| 摘要 |
PURPOSE:To enhance the detection accuracy of the failure diagnosis function of an air bag starting device without using any expensive detecting resistor and with a simple constitution by measuring the voltage of each part of the starting circuit to which a low voltage power supply is connected, and performing the failure diagnosis on the basis of these measuring result. CONSTITUTION:A transistor 31 is in off-condition and a transistor 32 is in on-condition while a vehicle is running. And when a safening sensor 1 and a transistor 61 are changed in on condition at the same time by the effect of a large negative acceleration, a squib ignition condenser 3 is rapidly discharged so that a large current may flow in a squib 5, and the action of an air bag is started. On the other hand, in time of self-diagnosis, a transistor 32 is changed in off-condition, and both the transistors 31 and 61 are changed in on-condition. As the contact points 4 and 13 are in off-condition in such a situation, the failure detection current supplied from the low voltage power supply 10 flows through a detection resistor R4 in the safening sensor 1, the squib 5 and transistor 61. Hence, the current flowing into the squib 5 is suppressed a low value. |
