Abnormality cause determining device, vehicular control device, and vehicular control system

An abnormality cause determining device that is applied to a vehicle including an electromagnetic actuator, comprising:

• a storage device configured to store map data which is data for defining a map, the map including a current variable which is a variable indicating a current actually flowing in the electromagnetic actuator as an input variable and including a cause variable which is a variable indicating a cause of an abnormality of an onboard unit including the electromagnetic actuator as an output variable;
• and
• an execution device configured to perform an acquisition process of acquiring a value of the input variable based on a detection value from a sensor which is mounted in the vehicle and a calculation process of calculating a value of the output variable by inputting the value of the input variable to the map, wherein
• the onboard unit is a gear shifting device that changes a gear shift ratio between a rotation speed of a rotation shaft of a rotary machine which is mounted in the vehicle and a rotation speed of driving wheels,
• the electromagnetic actuator includes a solenoid valve of the gear shifting device, and
• the current variable which is the input variable includes a variable indicating a current flowing in the solenoid valve in a switching period of the gear shift ratio in the gear shifting device, wherein
• the storage device is configured to store a plurality of pieces of map data which differs depending on a torque variable which is a variable indicating a torque applied to the driving wheels,
• the acquisition process includes a process of acquiring a value of the torque variable, and
• the calculation process includes a selection process of selecting the map data corresponding to the value of the torque variable acquired through the acquisition process out of the plurality of pieces of map data as the map data defining the map for calculating the value of the output variable.