Shift-by-wire system

A shift-by-wire system for a vehicle, said system comprising:

• an automatic transmission that outputs torque received from a drive power source upon changing a rotational speed;
• a range position changing means for changing a shift range of the automatic transmission to one of a plurality of ranges, which includes a P range, an R range, an N range and a D range, wherein the range position changing means is driven by an electric motor;
• a range control means for controlling electric power, which is supplied from an electric power source to the electric motor through an electric power supply system, and for controlling the shift range of the automatic transmission to one of the plurality of ranges;
• a capacitor that stores electric power to be supplied to the range position changing means and the range control means;
• and
• a manual P range releasing means for changing the shift range of the automatic transmission from the P range to another one of the plurality of ranges without using drive force of the electric motor,
• wherein
• the range control means determines whether the vehicle is stopped when the range control means senses an abnormality of at least one of the electric power source and the electric power supply system which disables supply of a required level of electric power from the electric power source to the electric motor;
• and
• wherein, when the range control means determines that the vehicle is stopped upon sensing of the abnormality, the range control means shifts the shift range of the automatic transmission to the P range through the range position changing means upon supplying electric power from the capacitor to the range position changing means to drive the electric motor in a case where the shift range of the automatic transmission is currently other than in the P range.