What does it mean?
Automatic transmissions, whether conventional or continuously variable transmissions (CVT), use fluid pressure to actuate changes inside the transmission. This can be anything from initiating gear changes to torque converter lockup or just softening shift points for a smooth drive. The line pressures that control these functions are metered by pressure control solenoids. Pressure control solenoid A performs some of these functions in your automatic transmission.
Depending on the vehicle design, pressure control solenoid A assists in shift controls in higher gear ranges, performs torque converter lockup duties, or both. It does so by regulating fluid pressure to the internal drum bands and friction plate clutches. Pressure control solenoids are electronically controlled through the powertrain control module or transmission control module.
When the circuit is energized, pressure control solenoid A allows actuation of other transmission controls via fluid pressure. For example, on the GMC Acadia, actuating pressure control solenoid A allows actuation of the clutch boost valve and the clutch regulator valve. When DTC P0747 is present, it indicates that pressure control solenoid A is stuck in the open position and the Check Engine light is illuminated.