Transmission control units are hydraulic or electrohydraulic components for operating automatic transmissions in cars and trucks. Electrohydraulic transmission control units (EGS) consist of hydraulic and electronic control components. The electronics determine the optimum time for a gearshift, while the clutch and gearshift operations are actuated by solenoid valves and hydraulic actuation of the actuators in the transmission. The electronic transmission control system takes numerous sensor data into account when determining the correct time for shifting, including information on engine speed, engine load, speed, driving programme and transmission oil or coolant temperature. In addition to critical system conditions, such as excessive operating temperatures, seasonal characteristics, gradients or inclines can also be taken into account. As a side effect, safety and driving comfort increase, while fuel consumption and pollutant emissions are reduced. Electrohydraulic transmission control systems offer the driver a choice of particularly economical or sporty driving modes.