ThePowertrain Control Module (PCM) controls the vehicle's automatic transmission. To achieve this, it relies on the input signals from the transmission sensors with which the shift strategy is calculated. The PCM activates the solenoids to allow the high-pressure fluid from the transmission to pass into the corresponding hydraulic circuit in the valve body.
When the error code P0780 OBDII is stored, it is because the PCM found a difference in RPM between the rotation speed of the input shaft and the output shaft of the transmission, as there are gear changes. This difference may be greater or less than that specified by the manufacturer.