A. Neutral Operation

In neutral and all forward ranges, the reverse signal pressure forces the gain valve away from the trim valve, resulting in trim signal pressure acting directly on the trim valve.

In reverse range, the reverse signal pressure is exhausted, which allows the gain valve to contact the trim valve. Trim signal pressure acts on top of the gain valve and the force is transmitted to the trim valve. Because the gain valve diameter is larger than the diameter of the second stage trim valve, a higher clutch pressure for a given trim signal pressure achieved.

Accumulators help regulate trim solenoid signal pressure. The trim valve bores in the valve body have cast slots in the area of main pressure and exhaust, which increases the stability of the trim valves and allows the clutch pressure to be more accurately controlled.

5–3. HYDRAULIC CONTROL SYSTEM CIRCUITS

A. Hydraulic Circuit—Neutral (Foldout 5) • In neutral, A Trim Solenoid is in its N/C state (de-energized), B Trim Solenoid is in its N/O state (de-energized), C, D, and E Solenoids are energized, and Trim Solenoid F remains de-energized. • C, D, and E Solenoids supply control main pressure to the top of Shift Valves C, D, and E, moving the valves downward against spring force.

• With Shift Valve C stroked down, control main pressure is directed through Shift Valve

C to pressure switch C, turning the switch on.

With Shift Valve D down, the exhaust path is blocked for the control main pressure being supplied through an orifice to the D pressure switch, and the pressure raises to control main and the D pressure switch turns on. With Shift

Valve E down, the exhaust path is blocked for the control main pressure being supplied through an orifice to the E pressure switch, and the pressure raises to control main and the

E pressure switch turns on. With Pressure Switches C, D, and E ON, feedback is provided to the TCM that Shift Valves C, D, and E are stroked.

• N/C A Trim Solenoid blocks the exhaust of the A trim signal pressure, raising the trim signal pressure. The A trim signal pressure forces Trim Valve A down, raising the A trim pressure which is directed to Shift Valve D. In its downward position, Shift Valve D routes fluid to C5 clutch, applying the clutch. All other clutches are exhausted.

• With only one clutch applied, the transmission is in neutral.

• If electrical power is interrupted while neutral is selected, C, D, and E Solenoids are deenergized and Shift Valve C moves upward.

Due to valve timing, when power is lost, Shift

Valve C strokes faster than Shift Valve E.

When Shift Valve C strokes up, control main pressure is fed through Shift Valve C to the top of Shift Valve E, keeping the valve down. N/C

A Trim Solenoid continues to block the exhaust of the solenoid signal pressure (solenoid signal remains control main). The solenoid signal pressure on top of Trim Valve

A produces maximum trim pressure, which is routed to Shift Valve D. Shift Valve D stayed down due to the “latching” effect of C5 clutch pressure acting on two different diameter lands. In its downward position, pressure continues to be routed to C5 clutch, keeping the clutch applied. Since only one clutch is applied, the transmission remains in neutral.

• If electrical power is interrupted with the transmission in neutral and the manual selector valve is moved to forward range or reverse, the transmission stays in neutral because Shift Valve E stays down and main pressure is blocked from reaching the Manual

Selector Valve.

• If the engine is shutdown and restarted with the electrical power interrupted to the

TCM, Shift Valves C, D and E will remain up.

N/C A Trim Solenoid blocks the exhaust of the A trim signal pressure (trim signal pressure becomes control main). The solenoid