Fourth Band Releases

WARNING: This page is about a different variant/trim than selected.

1-2 Shift Solenoid (SS) Valve

The 1-2 SS valve de-energizes (turns OFF), allowing the 1-2 SS valve fluid pressure (acting on the end of the 3-4 shift valve) to exhaust through the solenoid. Low fluid pressure acts on the solenoid valve fluid circuit. Spring force, acting on the opposite end of the valve, forces the 3-4 shift valve to move.

Fourth Servo Assembly

Spring force actuates the fourth servo piston. This force returns the piston to its band released position. This movement forces fourth band fluid from the other side of the piston. The fluid is forced back through its circuit to the 1-2 shift valve.

1-2 Shift Valve

Spring force and pressure from the 2-3 shift solenoid (SS) valve hold the 1-2 shift valve in the upshifted position. The fourth band fluid is routed back through the valve and into the fourth band feed circuit. Fourth band feed is then routed to the 3-4 shift valve.

3-4 Shift Valve

Spring force and D321 fluid hold the 3-4 shift valve in the downshifted position. Fourth band fluid from the 1-2 shift valve is routed through the valve into the orificed D21Y fluid passage. Orificed D21Y fluid is then routed through the 2-3 shift valve, where the fluid exhausts.