Control device for internal combustion engine and control method for cooling device

A control device comprising:

• a computer that is configured to control a cooling device, the cooling device including:
• a first cooling medium passage provided in a cylinder head of an internal combustion engine;
• a second cooling medium passage provided in a cylinder block of the internal combustion engine;
• a control valve that changes a ratio of a refrigerant flow rate of the first cooling medium passage to a refrigerant flow rate of the second cooling medium passage;
• and an electric water pump that circulates the refrigerant, wherein the computer is configured to:
• control the electric water pump such that a rotation speed of the electric water pump approaches an instruction rotation speed;
• diagnose an occurrence of an abnormality of the electric water pump in which the rotation speed of the electric water pump does not reach the instruction rotation speed while the electric water pump is rotating;
• and
• when the abnormality occurs, control the control valve so as to reduce a ratio of the refrigerant flow rate of the second cooling medium passage to the refrigerant flow rate of the first cooling medium passage, thus increasing the ratio of the refrigerant flow rate of the first cooling medium passage to the refrigerant flow rate of the second cooling medium passage.