For a view of the oil flow diagrams, refer to the 1996 TURM
manual.
In order to obtain the 4-3 downshift, the PCM receives an input signal
from the TP Sensor at increased throttle openings. This causes the PCM to
de-energize the 1-2 solenoid.
1-2 Shift Solenoid (1-2 SS) Valve: When the 1-2 SS Valve is de-energized, signal A fluid exhausts at the
solenoid valve. This allows spring force to move the 3-4 shift valve to the
extreme right.
3-4 Shift Valve: The fourth clutch apply pressure is shut off and a port is opened at
the valve. This exhausts the fourth clutch fluid which leaves the fourth clutch
and the fourth clutch accumulator. The fourth clutch releases, shifting the
transmission into third gear.
Fourth Clutch: Fluid which exhausts from the fourth clutch unseats the #10 checkball.
This allows for a rapid exhausting of the fourth clutch apply fluid at the
3-4 shift valve.
Fourth Clutch Accumulator: Fluid which exhausts from the fourth clutch accumulator also exhausts
through the unseated #10 check valve and exhausts at the 3-4 shift valve.