Control device, and processing method in event of failure in control device

A processing method in the event of a failure in a control device, which is executed in the control device including a failure diagnosis microcomputer configured to identify a phenomenon that is a cause of the detected error, and, a calculation microcomputer configured to shift an operation mode in response to a notification from the failure diagnosis microcomputer,

• the processing method comprising the steps of:
• calculating, by the failure diagnosis microcomputer, a diagnosable time available to be spent on the identification of the phenomenon that is the cause of the error;
• and
• identifying, by the failure diagnosis microcomputer, for each detected error, a phenomenon that is the cause of the error based on a posterior probability, which is calculated for each phenomenon that is likely to be the cause of the error as a probability of occurrence of the phenomenon, on a diagnosis time, which is obtained for each phenomenon as a period of time required to identify the phenomenon as the cause of the error, and on the diagnosable time.