Pressure Control Solenoid (PCS)
WARNING: This page is about a different car, the 2004 Suzuki Swift + and 2004 Chevrolet Aveo. However, it is still accessible from the selected car via links, so may be relevant.
The PCS (1) is located inside the valve body and regulates the transmission's fluid pressure system. It is internally grounded in the TCM and operates when it is supplied with battery voltage from the TCM, through the PCS and back to the TCM.
The battery voltage is controlled by a varying current from the TCM.
The strength of the current is a function of the throttle position.