A vehicle is provided with an electric machine and a storage device. The electric machine is configured to provide drive torque and the storage device is configured to supply power to the electric machine. The vehicle includes a variable voltage converter (VVC) that is connected between the storage device and the electric machine. The vehicle also includes a controller that is configured to receive input indicative of a VVC input current and a VVC output voltage. The controller is further configured to selectively disable drive torque responsive to the input.