Vehicle hydraulic system monitoring system and method

The present invention relates to a system for monitoring and protecting a vehicle hydraulic system. A system and method are provided for monitoring a vehicle hydraulic system having a plurality of hydraulic function elements. The hydraulic system includes a hydraulic pump for supplying pressurized hydraulic fluid to the plurality of hydraulic function elements via a corresponding plurality of hydraulic element control valves, an electronic control unit for controlling the element control valves. The pump also supplies lube fluid to a lubrication circuit if requirements of the hydraulic function elements are met. The method includes sensing a hydraulic pressure (preferably the lube pressure of lube fluid in the lube circuit), and comparing the sensed pressure to a threshold pressure. If the sensed pressure is less than threshold pressure, then actively engaged hydraulic elements are tested by disengaging the elements in a predetermined manner, checking to see if the sensed low pressure condition is eliminated. If the sensed low pressure condition is eliminated after disengaging an element, then the leaking hydraulic function element (the last element disengaged) is deactivated (locked-out) and a corresponding message is generated and stored.