Abstract

A method for operating a hydraulic closure system for a motor vehicle includes automatic opening and closing, as well as manual closing, of a closure pivotally mounted to an opening frame defining a closure opening in the motor vehicle. The system used in the method includes at least one hydraulic actuator assembly attached at opposite ends thereof to the closure and the opening frame, respectively. A motorized hydraulic pump inputs energy to the actuator to move the closure from the opened position to the closed position, and a biased energy storage system inputs energy to the actuator to move the closure from the closed position to the opened position. In a preferred embodiment, the pump is activated by relatively slow manually generated movement of the closure from the opened position toward the closed position. Also, an obstacle detection mechanism detects obstacles interfering with closing of the closure based on monitored pressure in the system. A level detection and compensation feature adjusts the amount of energy stored in the biased energy storage system for opening the closure based on the detected inclination or declination of the vehicle so that the amount of energy stored is commensurate with the amount required to open the closure.