Manual Second - Second Gear (From Manual Third - Third Gear)

Manual Second - Second Gear (From Manual Third - Third Gear):

Description:

MANUAL SECOND - SECOND GEAR (from Manual Third - Third Gear)

A manual 3-2 downshift can be accomplished by moving the gear selector lever into the Manual Second (2) position when the transmission is operating in Third gear. This causes the transmission to shift immediately into Second gear regardless of vehicle operating conditions. Refer to Overdrive Range: 3-2 Downshift for a complete description of a 3-2 downshift. Also, the transmission is prevented from operating in any other gear, First, Third or Fourth. The following information explains the additional changes during a manual 3-2 downshift as compared to a forced 3-2 downshift.

Manual Valve: The selector lever moves the manual shaft and manual valve into the Manual Second (2) position. This allows line pressure to enter the D2 fluid circuit.

Pressure Switch Assembly (PSA): D2 fluid is routed to the PSA where it opens the normally closed D2 fluid pressure switch. With the D2, and D3 pressure switches closed and the D4 pressure switch open, the PSA signals the PCM that the transmission is operating in Manual Second.

THIRD and FOURTH GEARS PREVENTED

2-3 Shift Solenoid: The PCM energizes the 2-3 shift solenoid and AFL fluid pressure holds the 2-3 shift valve in the downshifted position. This electronically prevents Third and Fourth gears.

2-3 Shift Valve Train: D2 fluid is routed between the 2-3 shuttle and 2-3 shift valves and causes the following:
- Regardless of operating conditions, D2 fluid pressure holds the 2-3 shuttle valve in the downshifted position against AFL fluid pressure.
- 2nd fluid is blocked from entering the 3-4 signal fluid circuit and the 3-4 signal fluid circuit is open to an exhaust port at the valve.
- The 3-4 clutch cannot apply with 3-4 signal fluid exhausted. Therefore, Third and Fourth gears are hydraulically prevented.
- 2nd fluid feeds the servo feed fluid circuit but has no function in Manual Second.
- AFL fluid is blocked by the 2-3 shift valve and the D432 fluid circuit is exhausted through the valve.
- Overrun fluid is exhausted through the 2-3 shuttle valve.

1-2 Shift Valve: The 1-2 solenoid is OFF, signal "A" fluid exhausts through the solenoid and spring force holds the valve in the upshifted position.

FIRST GEAR PREVENTED

The prevention of First gear in controlled electronically by the PCM through the 1-2 shift solenoid. The PCM keeps the 1-2 shift solenoid de-energized regardless of vehicle operating conditions when the PSA signals Manual Second gear range. This keeps signal "A" fluid exhausted and spring force holds the 1-2 shift valve in the upshifted position.

OVERRUN CLUTCH REMAINS APPLIED

Overrun Clutch Feed Checkball (#5): Orificed D2 fluid pressure seats the #5 checkball against the empty overrun clutch fluid circuit. This is done simultaneously with overrun clutch fluid exhausting such that there is a continuous fluid supply to the overrun clutch feed fluid circuit.

Overrun Clutch Piston: A continuous supply of fluid pressure is routed to the piston to keep the overrun clutch plates applied.

[1][2]Torque Converter Clutch - Second Gear: Under normal operating conditions the Torque Converter Clutch (TCC) will not apply in Second gear.

Pressure Control Solenoid: The PCM output signal to the force motor increases the operating range of torque signal fluid pressure in Manual Second. This provides increased line pressure for the additional torque requirements during engine compression braking and increased engine loads.