Line Pressure And Secondary Pressure Control: Notes

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.
Line pressure solenoid valve activates pressure regulator valve, and line pressure from oil pump is adjusted for the optimum driving condition. Secondary pressure is controlled by lowering line pressure.

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