For a view of the oil flow diagram, refer to the 1996 TURM
Manual.
A manual 3-2 downshift is initiated by moving the gear selector lever
to the Manual Second (2) position. However, the transmission will not downshift
into Second gear until vehicle speed is below approximately 99 km/h
(62 mph). At higher vehicle speeds the PCM will keep the 2-3 shift
solenoid energized (On) and the transmission will operate in Manual Second -
Third Gear as a safety precaution. In Manual Second the transmission is hydraulically
prevented from upshifting into Fourth gear under any conditions. Also, the
coast clutch remains applied as in Manual Third, and the clutch provides engine
compression braking in the Third and the Second gears. The transmission upshifts
and downshifts between First and Second gears as in Overdrive gear.
Manual Valve: Line pressure is routed into the D21 fluid circuit when the selector
lever is moved into the Manual Second (2) position. Line pressure continues
to feed the D321 fluid circuit as in Manual Third.
2-3 Shift Solenoid Valve: The PCM de-energized the 2-3 shift solenoid valve when the vehicle operating
conditions are appropriate for a 3-2 downshift. With the solenoid valve Off,
a 2-3 signal fluid exhausts through the 2-3 shift solenoid valve.
2-3 Shift Valve: A spring force moves the 2-3 shift valve into the Second gear position
when the 2-3 signal fluid exhausts. The D21 fluid continues through the valve
and the fluid is also routed into the intermediate band feed fluid circuit.
The 3-4 drive fluid, which feeds the direct clutch, exhausts past the 2-3
shift valve.
Direct Clutch Releases
Direct Clutch: The direct clutch fluid exhausts and the direct clutch releases.
#6 Checkball (Direct Clutch Release): Exhausting direct clutch fluid seats the #6 checkball. This fluid is
forced through the #25 orifice in order to help to control the direct clutch
release.
2-3 Accumulator: Direct clutch feed fluid exhausts from the 2-3 accumulator, unseats the
#5 checkball, and exhausts past the 2-3 shift valve. The 2-3 accumulator feed
fluid fills the 2-3 accumulator as the direct clutch feed fluid exhausts.
2-3 Accumulator Valve: The accumulator valve regulates line pressure into the 2-3 accumulator
fluid circuit in order to fill the 2-3 accumulator. A torque signal fluid
pressure controls this regulation. Accumulator fluid pressure is regulated
to a higher pressure with greater torque signal fluid pressure.
Intermediate and Fourth Band Applies
1-2 Shift Valve: The 1-2 shift solenoid valve is Off when the PCM commands the Second
gear. A spring force holds the 1-2 shift valve in the upshifted position.
Intermediate band feed fluid is routed through the valve and into the intermediate
band fluid circuit.
#3 Checkball (Intermediate Band Apply): Intermediate band fluid pressure seats the #3 checkball and is forced
through the #8 orifice. This orifice helps to control the intermediate band
apply.
Intermediate and Fourth Servo: Intermediate band fluid pressure is routed to the inner area of the intermediate
and Fourth servo piston. This fluid pressure moves the servo piston and apply
pin in order to apply the intermediate and Fourth band. The band provides
engine compression braking in Manual Second - Second Gear.
Pressure Control
A/T Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.)
Assembly: The D21 fluid from the 2-3 shift valve is routed to the TFP Val. Position
Sw. assembly, which signals to the PCM that the manual valve is in the Manual
Second position.
Pressure Control Solenoid Valve: The PCM increases the PCS duty cycle in order to increase 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 load in Manual Second.
Torque Converter Clutch: The PCM will release the TCC before downshifting into Manual Second.
The TCC will not reapply in Second gear under normal operating conditions.