Overdrive Range - Second Gear

Overdrive Range - Second Gear:

OVERDRIVE RANGE - SECOND GEAR

As the speed of the vehicle increases, the Powertrain Control Module (PCM) receives input signals from various engine and transaxle sensors. The PCM uses this data to de-energize solenoid "A" in order to shift the transaxle into second gear at the appropriate time.

SECOND CLUTCH APPLIES

Shift Solenoid "A": De-energized (OFF) by the PCM, it exhausts solenoid "A" fluid through the solenoid thereby creating a low solenoid "A" fluid pressure in the circuit. Low solenoid "A" pressure allows the 1-2 shift valve to move to the upshifted position and, the 3-4 shift valve moves to the downshifted position.

1-2 Shift Valve: Held in the upshifted position by low solenoid "B" fluid pressure and spring force, it allows orificed drive fluid to pass through the valve into the second clutch circuit. 2nd clutch fluid is then routed to the 1-2 accumulator piston and to the 2nd clutch piston in order to apply the clutch.

1-2 SHIFT ACCUMULATION

1-2 Accumulator Piston: Actuated by 2nd clutch fluid, it forces the piston to move against spring force and 1-2 accumulator fluid on the opposite side of the piston. 1-2 accumulator fluid is then forced back through its circuit to checkball #2.

#2 Checkball (Primary Accum1-2 Accum): Located the accumulator housing, it is unseated by 1-2 accumulator fluid allowing this fluid to enter the primary accumulator circuit. Primary accumulator is then routed to the 1-2 & 3-4 accumulator valve.

1-2 & 3-4 Accumulator Valve: Biased by torque signal pressure and orificed primary accumulator fluid, it regulates the exhaust rate of 1-2 accumulator fluid during a 1-2 shift.

LO/REVERSE RELEASES

Lo/Reverse Servo: When the 1-2 shift valve is held in the upshifted position, an exhaust port is opened. Fluid in the lo & reverse band reduce circuit exhausts at the valve while spring force, acting on the piston, forces the servo downward. The downward movement of the servo enables the release of the lo/reverse band.

#6 Checkball (Lo & Reverse Band Apply/Reduce): Positioned against the lo & reverse band apply circuit, it allows reverse band fluid from the lo/reverse servo piston to enter the lo & reverse band reduce circuit. Fluid in the lo & reverse band reduce circuit is then routed to the 1-2 shift valve where it exhausts.