The five-speed automatic transmissions of the AW 55-50 type are widely used in cars. They are used in the transmissions of Opel, Renault, Volvo, Saab, Fiat (Alfa, Lancia), Nissan and GM. Various problems are observed in their operation. Some of the problems are mechanical in nature, requiring major repairs to the transmission. A common defect is a problem in the valve body, which does not require major repairs. Only the valve body is dismantled and repaired without dismantling the entire gearbox. This the report examines characteristics of the linear pressure solenoid (electronic pressure regulator), embedded in automatic transmissions of the type AW 55-50. For this purpose, made special hydraulic fixture with electronic controls, which imitate the work of this pressure regulator under real conditions.