Fault diagnostic unit for a control circuit of a device for protecting the passengers of vehicles

摘要

A fault diagnostic device for monitoring a control circuit contains a firing capsule (6) which actuates an airbag or the like, a first (5) and a second (8) switching element for activating the firing capsule and a collision assessment circuit (20) which switches on the first and the second switching elements when a collision is detected above a predetermined level. The microcomputer (22) contained in the unit produces a signal which in each case switches on one of the two switching elements. The voltage between the actuated switching element and the firing capsule is then detected and compared by the microcomputer with the voltage during normal operation for the fault diagnosis. <IMAGE>