Throttle Pressure Control Solenoid Valve

This valve regulates the throttle pressure with help of TCM which controls the electric current to the solenoid according to the throttle opening of the engine.

The hydraulic pressure (line pressure) applied to this valve (1) goes through the valve into the chamber (A), trying to lower the valve. The plunger of the solenoid controlled by TCM acts on the upper end of the valve trying to lower the valve.

On the other hand, the force of the spring located under the valve works against these two forces, trying to raise the valve. As a result, the valve operates according to the throttle opening as described below to control the throttle pressure generated at (2).

When Throttle Opening Is Small
As TCM increases the amount of electric current supplied to the solenoid, the plunger moves down largely and the force to push the valve downward becomes larger. As a result, the valve lowers and the valve opening between (1) and (2) reduces, resulting in lower throttle pressure.

When Throttle Opening Is Large
As TCM reduces the amount of electric current supplied to the solenoid, the plunger moves less and the force to push the valve downward becomes smaller. As a result, the valve rises and the valve opening between (1) and (2) increases, resulting in higher throttle pressure.