When a 3-2 kickdown downshift is required, the fully depressed throttle prevents the throttle valve from regulating the incoming line pressure and throttle pressure becomes equal to line pressure.
Fluid at line pressure passes through the kickdown valve and acts on the top land of the 2-3 shift valve.
If road speed and therefore governor pressure is low enough, then the force provided will move the valve down and effect a change to 2nd gear.
If a change does take place, then as road speed increases, governor pressure will eventually overcome the opposing forces and move the shift valve upwards, even if the accelerator remains fully depressed.
If road speed is above a certain minimum, then a downshift will be denied, preventing the engine from over-revving.
