DECIDING DEVICE FOR FAULT OF VEHICLE SPEED SENSOR

摘要

PURPOSE:To find the fault of the vehicle speed sensor securely by providing an air flow sensor in an engine intake passage and further providing a means which decides on the fault when a detected vehicle speed value is lower than a specific value although the air suction amount is larger than the specific value. CONSTITUTION:The internal combustion engine E of an automobile is provided with the air suction passgae 1 for sending air. The air flow sensor 16 is provided at the upstream side of the air suction passage 1 to detect the air suction amount. The air flow sensor 16 uses a device which detects, for example, the number of Karman vortexes by ultrasonic modulation or from variation in resistance value and digitizes and inputs the detection result to a controller. A vehicle speed sensor 24, on the other hand, detects the vehicle speed and inputs it to the controller 29. The controller 29 decides on a fault when the detected value of the vehicle speed sensor 24 is smaller than the specific value while air more than the specific value is sucked through the air flow sensor 16. Thus, the fault of the vehicle speed sensor is detected securely and this device contributes to the improvement of safety.