Patent ID: 8447490

Claim:
A vehicle power transmission apparatus comprising: a torque converter that has a lockup clutch; a hydraulic pressure control circuit that is used to apply and release the lockup clutch; and a control unit that controls a hydraulic pressure feeding path in the hydraulic pressure control circuit, wherein: the hydraulic pressure control circuit includes a spool valve that is switched between a first state where an apply hydraulic pressure is input to the lockup clutch and a second state where a release hydraulic pressure is input to the lockup clutch, a solenoid valve that inputs to the spool valve a switching control hydraulic pressure for placing the spool valve in the first state or the second state, and a fail-safe valve that inputs to the spool valve a control hydraulic pressure for forcing the spool valve to be placed in the second state, independently of whether the switching control hydraulic pressure is input from the solenoid valve to the spool valve; and the control unit is adapted to execute: switching control that outputs to the solenoid valve a lockup ON command for placing the spool valve in the first state when a vehicle speed is detected to have become equal to or higher than a lockup ON determination value; fail-safe control that forcibly releases the lockup clutch by activating the fail-safe valve; abnormality diagnosis control that determines, when a vehicle has started with the fail-safe control executed, whether the solenoid valve is suffering from a solenoid ON abnormality; and reproduction control that simulatively reproduces, when the vehicle has started without the fail-safe control executed, a condition coinciding with an execution allowance condition for allowing execution of the abnormality diagnosis control.