GLOW PLUG DIAGNOSTIC METHOD AND GLOW PLUG DRIVE CONTROL DEVICE

It is possible to determine the presence or absence of the degradation and abnormality of a glow plug with high reliability using a relatively simple procedure. A method enables the determination of the presence or absence of degradation and abnormality with high reliability by measuring a resistance value of the glow plug 1, which is in an operating state, as a latest resistance value (S102), determining whether or not the rate of the change of the latest resistance value with respect to an initial resistance value of the glow plug 1 exceeds a first predetermined value (S104), determining whether or not the rate of the change of the latest resistance value with respect to a last resistance value that is a resistance value of the glow plug 1, which has been recently measured at the time of the acquisition of the latest resistance value, exceeds a second predetermined value b when the rate of the change of the latest resistance value with respect to the initial resistance value of the glow plug 1 exceeds the first predetermined value a (S106), and determining that the glow plug 1 is in an abnormal degradation state when the rate of the change of the latest resistance value with respect to the last resistance value exceeds the second predetermined value (S108).