Pontiac Fiero 1988 Service Manual page 764

HYDRAULIC DIAGNOSIS 125C-23
D R I V E R A N G E — T H I R D G E A R
C01WEITER CLUTCH - RELEASED FORWARD CLUTCH - APPLIED DIRECT CLUTCH - APPLIED
As both vehicle speed and governor pressure increase, the force of governor oil acting on the 2-3
shift valve overcomes the force of the 2-3 T.V. spring and shift T.V. oil. This allows the 2-3 shift valve
to open and R N D oil enters the direct clutch oil passage. This oil is called direct clutch oil.
Direct clutch oil from the 2-3 shift valve is directed to the following;
1. Direct Clutch Exhaust Checkball (1)
2. 3-2 Control Valve
3. Direct Clutch and Reverse Checkball (5)
4. Direct Clutch Accumulator Checkball (2)
5. Accumulator Check Valve
6. Intermediate Servo
7. 3rd Clutch Pressure Switch
BASIC CONTROL
Direct clutch oil from the 2-3 shift valve flows past the direct clutch exhaust checkball (1), past the
3rd clutch pressure switch, to the direct clutch and reverse checkball (5), seating it in the reverse
passage, and to the inner area of the direct clutch piston, applying the direct clutch. At the same
time, direct clutch oil is directed past the direct clutch accumulator checkball (2) into the direct clutch
accumulator passage, where it is called direct clutch accumulator oil, to the direct clutch accumulator
check valve, seating it; and to the release side of the intermediate servo. The pressure of the direct
clutch accumulator oil combined with the servo cushion spring, moves the servo piston against 2nd
oil and acts as an accumulator for a smooth intermediate band release and direct clutch apply.
Direct clutch oil also flows through the 3-2 control valve to the direct clutch accumulator passage.
SUMMARY
The forward and direct clutches are applied and the intermediate band is released; the transmission
is in Drive (D) Range — Third Gear (direct drive).
J H 0 0 2 2 - 1 2 5 C
Figure 20 Drive Range - Third Gear - Converter Clutch Released