Malfunction-detecting device for EGR stepping motor

摘要

A malfunction-detecting-device for an EGR stepping motor is provided wherein a circuit structure is furthermore simple and also more detailed malfunction information can be obtained by detecting the malfunction of the stepping motor during initialization drive of the stepping motor when an engine is just started. In order to determine that excitation coils of the EGR stepping motor have wire breaks, a driving-signal monitoring circuit is provide for monitoring a voltage surge as a monitoring signal generated by turning off a switching element for driving each of the excitation coils so as to cause self induction in the excitation coil. Malfunction detecting means of the EGR stepping motor is also provided for counting the number of monitoring inputs to the driving-signal monitoring circuit during initialization driving of the EGR stepping motor so as to determine the presence of wire breaks in the excitation coils when the number counted is less than the number of times the coils are driven.