Patent ID: 7013241

Claim:
An electronic control unit comprising a first computer and a second computer, characterized in that: the first computer includes a first diagnostic means for diagnosing operation of the first computer by performing a first diagnosis and a second diagnosis, in which a first value and a second value are calculated using at least two kinds of operations, a first comparison is performed between the first value and a pre-stored first reference value for determining whether a relationship between the first value and the first reference value is normal, and a second comparison is performed between the second value and a pre-stored second reference value for determining whether a relationship between the second value and the second reference value is normal; the first computer further includes a data transmitting means for sending a first set of diagnostic data regarding the first diagnosis and a second set of diagnostic data regarding the second diagnosis, respectively; the second computer includes a data receiving means for receiving the first set and the second set of diagnostic data; and the second computer further includes a second diagnostic means for determining whether the first diagnostic means normally operates based on the first and the second diagnostic data; the data transmitting means sends the first set of diagnostic data including the first calculated value and the first reference value as the first diagnostic data, and the second set of diagnostic data including the second calculated value and the second reference value as the second diagnostic data; the second diagnostic means performs a third diagnosis for determining whether a result of the first comparison is normal, and a fourth diagnosis for determining whether a result of the second comparison is normal; the first diagnostic means regularly performs the first comparison and the second comparison; the data transmitting means sends any one of the first set of diagnostic data and the second set of diagnostic data whichever most recently generated; and the second diagnostic means determines that the first diagnosis is halted when a period during which the receiving means has not received the first set of diagnostic data exceeds a predetermined reference period, and that the second diagnosis is halted when a period during which the receiving means has not received the second set of diagnostic data exceeds the predetermined reference period.