Overdrive Range - Second Gear

Overdrive Range - Second Gear:

OVERDRIVE RANGE - SECOND GEAR

As vehicle speed increases and operating conditions become appropriate, the PCM de-energizes shift 1-2 solenoid to shift the transaxle into Second gear. The manual valve remains in the Overdrive (D) position and line pressure is routed into the drive and PRND4 fluid circuits.

SECOND CLUTCH APPLIES

1-2 Shift Solenoid: The normally open shift solenoid is deenergized and 1-2 signal fluid exhausts through the open solenoid.

Note: Filtered actuator feed fluid continues to feed the 1-2 signal fluid circuit through orifice #7. However the exhaust port through the solenoid is larger than orifice #7 to prevent a pressure increase in the 1-2 signal fluid circuit.

1-2 Shift Valve: With 1-2 signal fluid pressure exhausted, spring force moves the valve into the upshifted position and drive fluid is routed into the 2-3 drive fluid circuit. Drive fluid also continues to flow through the valve and to the Pressure Switch Assembly (PSA).

#2 Checkball (Second Clutch Apply): 2-3 drive fluid seats the #2 checkball, forces 2-3 drive fluid through the #3 orifice and feeds the 2nd clutch fluid circuit. The #3 and #4 orifices help control the apply feel of the second clutch.

Second Clutch: 2nd clutch fluid pressure applies the Second clutch to shift the transaxle into Second gear.


SHIFT ACCUMULATION

1-2 Accumulator: 2nd clutch fluid is also routed to the 1-2 accumulator piston. 2nd clutch fluid pressure, in addition to 1-2 assist spring force, moves the piston against spring force and 1-2 accumulator feed fluid pressure. This action absorbs initial 2nd clutch fluid pressure to cushion the second clutch apply. The movement of the 1-2 accumulator piston forces some accumulator fluid out of the accumulator.

1-2 Accumulator Valve: 1-2 accumulator feed fluid forced from the 1-2 accumulator unseats the #4 checkball and is routed back to the 1-2 accumulator valve. This pressure forces the 1-2 accumulator valve against spring force and torque signal fluid pressure to regulate the exhaust of excess accumulator fluid. This regulation provides additional control for the second clutch apply. The figure shows the exhaust of accumulator fluid during the shift by the arrow directions in the accumulator fluid circuit.

TCC Control - Pulse Width Modulated (PWM) Solenoid: Filtered 2-3 drive fluid is routed to the Torque Converter Clutch (TCC) control solenoid. Under normal operating conditions the TCC control solenoid is OFF in Second gear and blocks filtered 2-3 drive fluid from entering the TCC signal fluid circuit.

Torque Converter Clutch: With the TCC control solenoid OFF the converter clutch is released in Second gear.

2-3 Shift Solenoid: 2-3 Shift solenoid remains OFF in Second gear and 2-3 signal fluid exhausts through the normally open solenoid.

2-3 Shift Valve: Spring force keeps the 2-3 shift valve in the downshifted position. In this position the valve blocks 2-3 drive fluid in preparation for the upshift to Third gear.