4-3 Downshift (Valves In Third Gear Position)

4-3 Downshift (Valves In Third Gear Position):

4-3 DOWNSHIFT (VALVES IN THIRD GEAR POSITION)

To obtain the 4-3 downshift, the Powertrain Control Module (PCM) receives an input signal from the Throttle Position Sensor (TPS) at increased throttle openings which causes it to de-energize solenoid "A".
^ Solenoid "A": De-energized, signal "A" fluid exhausts at the solenoid which allows spring force to move the 3-4 shift valve to the extreme right.
^ A Shift Valve: The fourth clutch apply pressure is shut off and a port is opened at the valve to exhaust fourth clutch fluid leaving the fourth clutch and fourth clutch accumulator. This causes the fourth clutch to release which shifts the transmission into third gear.
^ Fourth Clutch: Exhausting fourth clutch fluid unseats the #10 checkball which allows for a rapid exhausting of the fourth clutch apply fluid at the 3-4 shift valve.
^ Fourth Clutch Accumulator: Exhausting fourth clutch accumulator fluid also exhausts through the unseated #10 check valve and exhausts at the 3-4 shift valve.