Hydraulic pump failure detection for transmission with normally engaged clutch

A method of detecting the failure of a hydraulic pump in a vehicle having an engine with an automatic start/stop capability and a transmission with a normally engaged clutch, the method comprising:

• sensing a rotational speed of the engine;
• sensing a rotational speed of a rotating drivetrain component disposed downstream of a pump of a torque converter of the transmission, and not directly connected to an output of the transmission;
• calculating a numerical difference between the rotational speed of the engine and the rotational speed of the rotating drivetrain component;
• comparing the numerical difference between the rotational speed of the engine and the rotational speed of the rotating drivetrain component to a threshold value to determine if the numerical difference is less than the threshold value, or if the numerical difference is equal to or greater than the threshold value;
• identifying an operating mode of the transmission to determine if the transmission is positioned in a neutral gear mode, or if the transmission is positioned in one of a plurality of non-neutral gear modes;
• and
• identifying a failure of the hydraulic pump when the numerical difference between the rotational speed of the engine and the rotational speed of the rotating drivetrain component is equal to or greater than the threshold value, and the transmission is positioned in the neutral gear mode.

A vehicle comprising:

• an engine having an automatic start/stop capability;
• a transmission coupled to the engine and including a torque converter having a pump and a stator, and a normally engaged clutch operable to transfer torque in the absence of fluid pressure;
• a hydraulic pump coupled to the engine and operable to circulate a fluid through the transmission and to the normally engaged clutch when the engine is operating;
• a transmission control module operably connected to the transmission and operable to:
• receive a signal indicating the rotational speed of the engine;
• receive a signal indicating the rotational speed of a rotating drivetrain component disposed downstream of the pump of the torque converter, and not directly connected to an output of the transmission;
• calculate a numerical difference between the rotational speed of the engine and the rotational speed of the rotating drivetrain component from the signals indicating the rotational speed of the engine and the rotational speed of the rotating drivetrain component respectively;
• compare the numerical difference to a threshold value to determine if the numerical difference is less than the threshold value, or if the numerical difference is equal to or greater than the threshold value;
• identify an operating mode of the transmission to determine if the transmission is disposed in a neutral gear mode or in one of a plurality of non-neutral gear modes;
• identify a failure of the hydraulic pump when the numerical difference is equal to or greater than the threshold value, and the transmission is positioned in the neutral gear mode;
• and
• stop operation of the engine when a failure of the hydraulic pump is identified.