ECU POWER SUPPLY VOLTAGE MONITORING DEVICE AND METHOD

A method of monitoring a power supply voltage to an electronic control unit equipped with a vehicle by using a voltage monitoring device, comprising: detecting the power supply voltage to the electronic control unit; comparing the detected power supply voltage with a predetermined threshold value; accumulating an anomaly length of time during which the detected power supply voltage is lower than the predetermined threshold value; determining whether the accumulated anomaly length of time becomes a predetermined anomaly threshold time or more; and when it is determined that the accumulated anomaly length of time becomes the predetermined anomaly threshold time or more, determining that the anomaly occurs on the voltage monitoring device.