A hydraulic system of an automatic transmission for controlling fluid flow through the automatic transmission, comprising: a controller for operably controlling the system (200, 300); a variable displacement pump adapted to be driven by a torque-generating mechanism, the pump having an inlet and an outlet, where the pump is configured to generate fluid flow and pressure throughout the system; a main circuit fluidly coupled to the pump, the main circuit adapted to operate and control the transmission; a solenoid disposed in electrical communication with the controller, the solenoid controllably coupled to the pump to alter the displacement of the pump; a first circuit fluidly coupled to the outlet of the pump; a regulator valve disposed in fluid communication with the main circuit, the regulator valve being configured to move between a regulated position and an unregulated position, where the regulated position corresponds to a regulated pressure in the main circuit; a pressure switch fluidly coupled to the regulator valve and configured to move between a first position and a second position, wherein the pressure switch is disposed in electrical communication with the controller to regulate pump flow of the variable displacement pump; a second circuit fluidly coupled to the pump, the second circuit operably controlled to adjust a temperature of the fluid in the system, wherein a fluid flow through the second circuit is adjusted by the altered displacement of the pump based on the temperature of the fluid; a temperature sensor disposed in electrical communication with the controller, the temperature sensor adapted to detect the temperature of the fluid; and a plurality of flow paths in the system, the plurality of flow paths comprising at least a first flow path defined between the outlet of the pump and the regulator valve, a second flow path defined between the regulator valve and the main circuit, and a third flow path (234, 236) defined between the regulator valve and the second circuit, wherein fluid passed through the third flow path (234, 236) flows into the first circuit. a controller for operably controlling the system (200, 300); a variable displacement pump adapted to be driven by a torque-generating mechanism, the pump having an inlet and an outlet, where the pump is configured to generate fluid flow and pressure throughout the system; a main circuit fluidly coupled to the pump, the main circuit adapted to operate and control the transmission; a solenoid disposed in electrical communication with the controller, the solenoid controllably coupled to the pump to alter the displacement of the pump; a first circuit fluidly coupled to the outlet of the pump; a regulator valve disposed in fluid communication with the main circuit, the regulator valve being configured to move between a regulated position and an unregulated position, where the regulated position corresponds to a regulated pressure in the main circuit; a pressure switch fluidly coupled to the regulator valve and configured to move between a first position and a second position, wherein the pressure switch is disposed in electrical communication with the controller to regulate pump flow of the variable displacement pump; a second circuit fluidly coupled to the pump, the second circuit operably controlled to adjust a temperature of the fluid in the system, wherein a fluid flow through the second circuit is adjusted by the altered displacement of the pump based on the temperature of the fluid; a temperature sensor disposed in electrical communication with the controller, the temperature sensor adapted to detect the temperature of the fluid; and a plurality of flow paths in the system, the plurality of flow paths comprising at least a first flow path defined between the outlet of the pump and the regulator valve, a second flow path defined between the regulator valve and the main circuit, and a third flow path (234, 236) defined between the regulator valve and the second circuit, wherein fluid passed through the third flow path (234, 236) flows into the first circuit.