Steering angle detecting system for automotive vehicles

摘要

A steering angle detecting system for a vehicle includes a sensor responsive to rotation of a steering wheel for generating angular pulses corresponding in number to the steering angle of the steering wheel. Another sensor generates a reference pulse at a predetermined angle of the steering wheel. The angular pulses are counted by a counter. The steering angle detecting system is determined to be abnormal if the counted value of the counter is not within a predetermined value range when the reference pulse is generated. Further, the rate of change of the counted value by the counter is detected, and the steering angle detecting system is determined to be abnormal if the detected rate of change of the counted value is greater than a predetermined value. Further, the steering angle detecting system is determined to be abnormal if the detected rate of change of the counted value has continued to be smaller than a predetermined value for a predetermined time period or longer.