In order to obtain second gear, the PCM receives input signals
from the transmission speed sensors (input and output), the Throttle Position
(TP) Sensor, and from other engine sensors. These signals determine when
to de-energize the 1-2 Shift Solenoid (SS) Valve.
Manual Valve: In the Overdrive range second gear, line pressure from the pressure
regulator valve is directed as PRND4, PRND43, and Drive fluid pressures. The
PRND4 fluid pressure is directed to the Automatic Transmission Fluid Pressure
(TFP) Manual Valve Position Switch Assembly and to the 2-3 shift valve.
The PRND43 fluid is directed to the TFP manual valve position switch and
to the manual 2-1 band servo. The Drive fluid is directed to the TFP
manual valve position switch, the forward clutch, the 1-2 shift valve,
and the accumulator valve.
Automatic Transmission Fluid Pressure (TFP) Manual Valve Position Switch
Assembly: Drive, PRND4, and PRND43 fluid pressures from the manual valve
are directed to the DR, PRND4, and the PRND43 switches on the TFP manual valve
position switch. This sends a signal to the PCM that the transmission is
in Overdrive range.
1-2 Shift Solenoid (1-2 SS) Valve: When the 1-2 SS valve is de-energized, 1-2 signal
fluid exhausts through the solenoid. A spring force holds the 1-2 shift
valve to the extreme right.
2-3 Shift Solenoid (2-3 SS) Valve: When the 2-3 SS valve is de-energized, 2-3 signal
fluid pressure forces the 2-3 shift valve to the extreme right against
a spring force.
1-2 Shift Valve: Spring force holds the 1-2 shift valve to the extreme right.
Drive fluid pressure from the manual valve changes into 2-3 drive fluid
pressure at the 1-2 shift valve. This pressure is directed to the
2-3 shift valve, to the TCC PWM Solenoid Valve, and to the
intermediate (second) clutch.
2-3 Shift Valve: Spring force holds the 2-3 shift valve to the extreme right.
The 2-3 drive fluid pressure from the 1-2 shift valve changes
into Front Band Apply (FBA) and is directed to the manual 2-1 band
servo. The PRND4 fluid pressure from the manual valve is held at the 2-3 shift
valve in order to be utilized in other gear ranges.
3-4 Shift Range: Spring force holds the 3-4 shift valve to the extreme right.
Forward Clutch: Drive fluid pressure from the manual valve applies the forward
clutch.
Intermediate (Second) Clutch: Second fluid pressure from the 1-2 shift valve applies the
intermediate clutch. The 2-3 drive fluid pressure from the 1-2 shift
valve seats the #4 checkball, causing the fluid to flow through two
orifices and into the center support. This applies the Intermediate (Second)
clutch. The 2-3 drive fluid pressure changes into Second apply fluid
pressure at the orifices.
Overdrive Range, Second Gear