The valve body is a metal valve plate in which many channels are made. These channels contain special valves (often called solenoids), as well as electronic sensors.
Taken together, these elements actually control the operation of the automatic transmission based on signals from the automatic transmission ECU. For this reason, in everyday life, it is customary to call the valve body the “brain” of the box – automatic since the hydraulic plate controls the operation of the automatic transmission.
As for the principle of operation, the automatic transmission valve body passes the transmission fluid through the channels, that is, transfers the ATF fluid’s pressure to the gearbox’s mechanical elements. Thanks to this, gears are switched on and off in automatic mode.
There are separate channels in the hydraulic plate for each gear. A signal from the automatic transmission ECU comes to the valves (solenoids) to turn on a particular gear. The required valve is triggered, as a result of which the channel opens, the ATP fluid under pressure flows through the channel.