Line Pressure And Secondary Pressure Control

WARNING: This page is about a different car, the 2011 Nissan Juke. However, it is still accessible from the selected car via links, so may be relevant.

When an input torque signal equivalent to the engine driving force is transmitted from the ECM to the TCM, the TCM controls the line pressure solenoid valve and secondary pressure solenoid valve.
Highly accurate line pressure control and secondary pressure control reduces friction for improvement of fuel economy.

Fig 1: Line And Secondary Pressure Control Schematic
Courtesy of NISSAN MOTOR CO., U.S.A.