Hydraulic system for an automatic transmission of a motor vehicle

A hydraulic system for an automatic transmission, in particular a dual-clutch transmission, of a motor vehicle, comprising:

• a high-pressure circuit, in which a pressure accumulator, at least one clutch, and gear selectors are connected, and comprising:
• a low-pressure circuit for cooling the clutch, wherein the high-pressure circuit and the low-pressure circuit have at least one hydraulic pump, which can be driven by an electric motor, said hydraulic system also having a control unit, which activates the electric motor of the hydraulic pump when a requirement to charge the pressure accumulator is identified, wherein the high-pressure and low-pressure circuits are connected via a bypass line to an integrated accumulator charging valve, which in a non-charging position fluidically connects the hydraulic pump to the low-pressure circuit and in a charging position fluidically connects the hydraulic pump to the high-pressure circuit, wherein the accumulator charging valve switches automatically from the charging position to the non-charging position at a first switchover time if the accumulator pressure in the high-pressure circuit exceeds an upper pressure threshold value (pmax), and switches automatically from the non-charging position to the charging position at a second switchover time if the accumulator pressure drops below a lower pressure threshold value, wherein the control unit has a diagnostic module, by which a valve spread diagnosis is performed, in which an actual valve spread between the lower and upper pressure threshold values can be determined, and the diagnostic module has an analysis unit, which compares the actual valve spread with a target valve spread and, if a significant deviation is found, diagnoses a fault, which can be stored in a valve spread fault memory.