H. Reverse Operation

• If electrical power is interrupted with the transmission is in fifth range, (fifth range converter operation) and the Manual Selector

Valve is moved to reverse, C2 clutch exhausts through the Manual Selector Valve, releasing the clutch. C3 clutch remains applied. With only one clutch applied, the transmission goes to neutral.

• If electrical power is interrupted with the transmission is in fifth range, resulting in only fifth and neutral operation, the engine may be shut down and restarted to attain neutral, third and reverse operation (reference Section A—

Neutral).

H. Hydraulic Circuit—Reverse (Foldout 11)

• When the Manual Selector Valve is moved from neutral to reverse and the throttle setting is above closed throttle, C, D, and E Shift

Solenoids remain energized, A Solenoid remains de-energized, supplying A Trim pressure through Shift Valve D, to the C5 clutch, keeping the C5 clutch applied. B

Solenoid remains de-energized, keeping B

Trim pressure exhausted. With only C5 clutch applied, the transmission remains in neutral.

Reverse signal pressure is exhausted, removing pressure from the reverse pressure switch, turning on the normally closed reverse pressure switch. When the Manual Selector

Valve is moved from neutral to reverse and the

TCM determines that the engine is at closed throttle, B Trim Solenoid energizes, which acts on the Trim Valve B gain valve because reverse signal pressure no longer pushes the valve up. The gain valve pushes the B Trim

Valve down, raising B Trim pressure. B Trim pressure is directed through Shift Valves C and E, the Manual Selector Valve, the TCC

Valve to Shift Valve D, stroking the valve up (even though D Solenoid stays energized).

With Shift Valve D up, pressure from Trim

Valve B passes through Shift Valves C and E, through the Manual Selector Valve, the TCC

Valve, and Shift Valve D to the C5 clutch, keeping the clutch applied. Pressure from Trim Valve A, which was applying the C5 clutch through Shift Valve D, is directed through Shift Valve D to the C3 Clutch.

• The TCM temporarily energizes A Solenoid to control the rate at which Trim Valve A supplies pressure to the oncoming C3 clutch, assuring a smooth transition to reverse. When

A Solenoid energizes, A Trim signal pressure is exhausted. As A Solenoid is de-energized, A

Trim signal pressure increases. Initially, the

Trim Valve A gain valve spring keeps the gain valve away from Trim Valve A, so only the A trim signal pressure acts on Trim Valve A. As the A Trim signal pressure increases, the A

Trim pressure increases. The A Trim signal pressure also acts on the gain valve, forcing the valve down and compressing the gain valve spring. When the gain valve spring is compressed sufficiently, the gain valve contacts Trim Valve A. The gain valve spring allows the C3 clutch initial apply to be controlled at a lower gain rate, improving control of the oncoming C3 clutch. Once the gain valve makes contact with Trim Valve A,

A Trim pressure increases at a higher gain rate. When the shift to reverse is complete,

A Solenoid fully de-energizes and Trim Valve

A supplies full trim pressure to the C3 clutch.

B Solenoid remains fully energized and B

Trim valve supplies full trim pressure to the

C5 clutch.

• The application of C3 and C5 produces reverse range operation.

• Even though Shift Valve D moves up due to B

Trim pressure, B Trim pressure acts on

Pressure Switch D, keeping Pressure Switch D on. Shift Valve C remains stroked down, directing control main pressure through Shift

Valve C to Pressure Switch C, keeping the switch on. Shift Valve E remains stroked down blocking the exhaust path for control main pressure being supplied through an orifice to

Pressure Switch E; the pressure keeps

Pressure Switch E on. With reverse signal pressure exhausted the normally closed

Reverse Pressure Switch is on, providing

feedback to the TCM that the selector valve is in reverse.

NOTE: Before implementation of N04 software, C Solenoid always remained energized in reverse range. Beginning with the N04 software, C Solenoid will de-energize, providing certain throttle conditions are met. Throttle percentages are calibration dependent and may vary between TCMs.

• If 20 percent throttle is applied and does not drop to 10 percent, all shift solenoids remain energized. If the throttle drops to 10 percent and stays below 20 percent, C Solenoid deenergizes, removing pressure from the top of

Shift Valve C, allowing Shift Valve C to stroke up. B Trim pressure is no longer routed to the bottom of Shift Valve D, so D Solenoid pressure strokes the shift valve D down. B

Trim pressure goes through Shift Valves C, E, and D to the C3 clutch, keeping the C3 clutch applied. A Trim pressure goes through Shift

Valve D to the C5 clutch, keeping C5 clutch applied. With C3 and C5 clutches applied, reverse range is maintained. If 20 percent throttle is applied and does not drop to 10 percent, C Solenoid energizes, applying pressure to the top of Shift Valve C, stroking the valve down. B Trim pressure is directed through Shift Valves C and E, the Manual

Selector Valve, and the TCC Valve to Shift

Valve D, stroking the valve up (even though D

Solenoid stays energized). With Shift Valve D up, pressure from Trim Valve B passes through Shift Valves C and E, the Manual

Selector valve, the TCC Valve, and Shift Valve

D to the C5 clutch, keeping the clutch applied.

Pressure from Trim Valve A, which was applying the C5 clutch through Shift Valve D, is now directed though Shift Valve D to the C3

Clutch, keeping the C3 Clutch applied. With

C3 and C5 clutches applied, reverse range is maintained.

• If electrical power is interrupted with the transmission operating in reverse and 20 percent throttle was applied and did not drop to 10 percent before the power interruption, B, C, D, and E Solenoids de-energize. Control main pressure is removed from the top of Shift Valve D, keeping the valve up. When deenergized, normally open B Trim Solenoid exhausts the B Trim signal pressure, allowing Trim Valve B to move up, exhausting and releasing the C5 clutch. Shift Valve C moves before Shift Valve E, directing control main pressure to the top of Shift Valve E, “latching” it in the down position. Trim Valve A continues to apply pressure through Shift Valve D to the C3 clutch, keeping the C3 clutch applied. With only one clutch applied, the transmission shifts to neutral range.

• If electrical power is interrupted with the transmission operating in reverse and 20 percent throttle was applied and did not drop to 10 percent before the power interruption, resulting in neutral operation, and if the

Manual Selector Valve is moved to neutral, main pressure going through Shift Valves E and D is blocked by the Manual Selector valve from applying either the C1 or C2 clutches.

The C3 clutch remains applied. With only one clutch applied, the transmission stays in neutral range.

• If electrical power is interrupted with the transmission operating in reverse and 20 percent throttle was applied and did not drop to 10 percent before the power interruption, resulting in neutral operation, and if the

Manual Selector Valve is moved to reverse, main pressure going through Shift Valves E and D is blocked by the Manual Selector valve from applying either the C1 or C2 clutches.

The C3 clutch remains applied. With only one clutch applied, the transmission stays in neutral range. • If electrical power is interrupted with the transmission operating in reverse and the throttle was above approximately 20 percent and did not drop to 10 percent before the power interruption, resulting in neutral operation, and if the Manual Selector Valve is moved to a forward range, main pressure goes through Shift Valves E and D and the Manual

Selector Valve, to the C2 clutch, applying the