Fourth Band Releases

WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.

1-2 Shift Solenoid (SS) Valve

The 1-2 SS valve de-energizes, allowing fluid pressure from the 1-2 SS valve (acting on the end of the 3-4 shift valve) to exhaust through the solenoid. With low fluid pressure in the 1-2 SS valve, spring force acting on the opposite end of the valve moves the 3-4 shift valve.

Fourth Servo Assembly

Spring force actuates the fourth servo piston and returns the piston to its band released position. This movement forces fourth band fluid from the other side of the piston 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. 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 holds 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 to the 2-3 shift valve where the fluid exhausts.