For 1990-2009 cars

In Neutral (N), pressure control solenoid A is in the normally closed state, de-energized, pressure control solenoid B is in the normally open state, de-energized, shift solenoids C, D, and E are energized, and the torque converter clutch pulse width modulated (TCC PWM) solenoid remains de-energized.

Shift solenoids C, D, and E 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 transmission control module (TCM) that shift valves C, D, and E are stroked.

Normally closed pressure control solenoid A blocks the exhaust of the A trim signal pressure, raising the trim signal pressure. The A trim signal pressure forces pressure control valve A down, raising the A trim pressure which is directed to shift valve D. In the downward position, shift valve D routes fluid to low and Reverse clutch, applying the clutch. All other clutches are exhausted.

With only one clutch applied, the transmission is in Neutral (N).

If electrical power is interrupted while Neutral (N) is selected, shift solenoids C, D, and E are de-energized 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. Normally closed pressure control solenoid A continues to block the exhaust of the solenoid signal pressure, and the 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 low and Reverse clutch pressure acting on two different diameter lands. In the downward position, pressure continues to be routed to low and Reverse clutch, keeping the clutch applied. Since only one clutch is applied, the transmission remains in Neutral (N).

If electrical power is interrupted with the transmission in Neutral (N) and the manual valve is moved to forward or Reverse (R), the transmission stays in Neutral (N) because shift valve E stays down and main pressure is blocked from reaching the manual 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. Normally closed pressure control solenoid A blocks the exhaust of the A trim signal pressure, and trim signal pressure becomes control main. The solenoid signal pressure on top of trim valve A produces maximum trim pressure, which is routed to shift valve D. In the upward position, shift valve D routes fluid to the 3rd, 5th, and Reverse clutch. All other clutches are exhausted, so the transmission remains in Neutral (N). When shift valve E is up, main pressure is routed through shift valve E to the manual valve. If forward is selected, the manual valve routes fluid to the 1-2-3-4 clutch. The 3rd, 5th, and Reverse clutch remains on with the 1-2-3-4 clutch, resulting in third range being attained for limp home capability. If Reverse (R) is selected, the selector valve directs fluid through the TCC valve and shift valve D to the low and Reverse clutch. The 3rd, 5th, and Reverse clutch remains on with the low and Reverse clutch, resulting in Reverse (R) range being attained.

#### Neutral