Torque Converter Clutch Solenoid Valve Control

The torque converter clutch solenoid valve is controlled by the TCM. The plunger closes the drain circuit during the OFF period, and opens the circuit during the ON period. If the percentage of OFF-time increases in one cycle, the pilot pressure drain time is reduced and pilot pressure remains high.

Fig 1: Lock-Up Operation Condition Chart

Courtesy of NISSAN MOTOR CO., U.S.A.

The torque converter clutch piston is designed to slip to adjust the ratio of ON-OFF, thereby reducing lock-up shock.

OFF-time INCREASING => Amount of drain DECREASING => Pilot pressure HIGH => Lock-up RELEASING

Fig 2: Lock-Up Applied And Released Graph

Courtesy of NISSAN MOTOR CO., U.S.A.