Lockup Operation

The duty solenoid allows the pilot pressure to be applied to the engaging end of the valve in the control valve body. The valve then opens the clutch engaging circuit port that communicates to the torque converters impeller chamber, allowing high pressure fluid to flow to the lockup clutch. The clutch then engages.

• The TCM controls the current to the duty solenoid by gradually changing the current. As a result, the valve also moves gradually, so the clutch engagement pressure increases smoothly. This causes the lockup clutch to become initially in a half-engaged state and then in a fully engaged state, thus preventing shock during engagement.

This control is performed in all gear positions.