The present disclosure provides a method of diagnosing an oil leak of an engine clutch in a hybrid electric vehicle including: when the engine starts up in the hybrid electric vehicle, operating a hydraulic actuator provided in the engine clutch, wherein the hydraulic actuator is configured to perform engagement or disengagement between an engine and a motor; determining displacement of a piston provided in the hydraulic actuator and pressure for any displacement of a plurality of the displacements of the piston; calculating a pressure gradient based on the displacement of the piston and the pressure for any displacement of the plurality of the displacements of the piston; and determining the oil leak of the engine clutch based on the pressure gradient.

The present disclosure provides a method of diagnosing an oil leak of an engine clutch in a hybrid electric vehicle including: when the engine starts up in the hybrid electric vehicle, operating a hydraulic actuator provided in the engine clutch, wherein the hydraulic actuator is configured to perform engagement or disengagement between an engine and a motor; determining displacement of a piston provided in the hydraulic actuator and pressure for any displacement of a plurality of the displacements of the piston; calculating a pressure gradient based on the displacement of the piston and the pressure for any displacement of the plurality of the displacements of the piston; and determining the oil leak of the engine clutch based on the pressure gradient.

A temperature warning method of a friction element for issuing a warning depending on temperature of the friction element arranged between a power source and a driving wheel, includes issuing the warning when the temperature of the friction element exceeds an upper limit temperature, and making a period of time, from when the temperature of the friction element exceeds the upper limit temperature until when the warning is issued, longer when the temperature of the friction element exceeds the upper limit temperature for a first time than when the temperature of the friction element exceeds the upper limit temperature for a second or subsequent time.

A power tool and a method of operating a power tool including a motor, a clutch collar including a plurality of settings, a wireless transceiver operable to form a wireless connection with a remote device, and a processor coupled to the clutch collar and the wireless transceiver. The processor receives, via the wireless transceiver, a mapping including a plurality of torque levels corresponding to the plurality of settings. The processor detects that the clutch collar is set to a setting of the plurality of settings. The processor determines the torque level for the setting from the mapping and detects, during the operation of the power tool, that a torque of the power tool exceeds the torque level. The processor is also configured to generate an indication that the torque exceeds the torque level. The indication may include flashing a light, ratcheting the motor, and stopping the motor.