System and method for controlling power transmission apparatus for vehicle

A control system, comprising:

• a power transmission apparatus that includes an engine;
• a first shift portion that includes a motor and a differential portion, and that is able to function as an electric differential portion;
• and a second shift portion that is a stepped shift portion, and that is connected to the first shift portion, wherein the power transmission apparatus transmits power output from the engine to a drive wheel;
• and
• a control device that includes a shift progress determination portion that determines whether a degree of progress of an upshift of the second shift portion that is performed when a vehicle is driven using solely the motor as a drive power source, has reached a predetermined level, wherein the control device determines whether the engine should be started;
• and when the upshift of the second shift portion is being performed, the shift progress determination portion determines that the degree of the progress of the upshift has not reached the predetermined level, and the control device determines that the engine should be started, the control device executes a control that stops the upshift, and starts me engine.