Disclosed is a hydraulic control system for an automatic transmission including a plurality of friction elements associated with respective transmission speeds. The hydraulic control system includes a hydraulic fluid source, a line pressure controller, a reducing pressure controller, a range controller, a shift controller, a hydraulic pressure controller, and a hydraulic pressure distributor. The hydraulic pressure distributor further includes a 3-4 shift valve, a 1-2 shift valve, a 2-3/4-3 shift valve, a 4-2 shift valve for realizing port conversion during a 4-2 skip-shifting process to selectively supply/exhaust the control pressure to/from at least one of the friction elements corresponding to the respective transmission speeds, a control switch valve for realizing port conversion to selectively supply/exhaust hydraulic pressure from the shift controller and the control pressure via the 1-2 shift valve to at least one of the friction elements corresponding to the respective transmission speeds, and a solenoid valve for controlling the control switch valve in accordance with a control signal from a transmission control unit.

A hydraulic control system for an automatic transmission, including a hydrualic pressure source, a hydrualic pressure regulator, a transmission mode selector, a shifting controller for automatically controlling shifting between transmission speeds in a given transmission mode, and a hydrualic pressure control mechanism for controlling quality and responsiveness of the shifting between transmission speeds. The hydrualic control system includes a fail safe valve for assuredly maintaining a certain transmission speed (such as third speed) when a transmission control unit (TCU) fails, or when a valve in the control system sticks or becomes inoperative.

A hydraulic control system for an automatic transmission including a plurality of friction elements associated with respective transmission speeds. The hydraulic control system includes a hydraulic fluid source, a line pressure controller, a reducing pressure controller, a range controller, a shift controller, a hydraulic pressure controller, wherein the hydraulic pressure distributor includes a 3-4 shift valve, a 2-3/4-3 shift valve, a 1-2 shift valve, a control switch valve for selectively supplying/exhausting hydraulic pressure from the shift controller to at least one of the friction elements corresponding to the respective transmission speeds to control operating timing of each corresponding friction element and supplying the hydraulic pressure from the shift controller to the line pressure controller to reduce line pressure at a high speed state; and a solenoid valve for controlling the control switch valve in accordance with a control signal of the transmission control unit.

A control system for controlling energization of a plurality of valves in a vehicle hydraulic system. The control system includes a plurality of sensors for measuring various dynamic conditions and operational aspects of the vehicle, a signal processing circuit coupled to the plurality of sensors for determining a desired energization of the plurality of valves dependent upon measurements by at least a portion of the plurality of sensors, and a driver circuit coupled to the signal processing circuit for generating, responsive to the desired energization of the plurality of valves as determined by the signal processing circuit, a control signal to energize the plurality of valves to the desired energization. The control system receives inputs from the plurality of vehicle sensors. These inputs are processed, and the processed inputs and signals derived from the inputs are forwarded to the driver circuit for use in generating a control signal for operating the vehicle valve system. In a particular embodiment, the valve system is controlled to operate a plurality of hydraulic actuators to provide a desired configuration of the vehicle.