Overdrive Range - Fourth Gear (Converter Clutch Applied)

Overdrive Range - Fourth Gear (Converter Clutch Applied):

OVERDRIVE RANGE FOURTH GEAR (CONVERTER CLUTCH APPLIED)

SOLENOID "A" - ON
SECOND CLUTCH - APPLIED
1/2 SUPPORT ROLLER CLUTCH - OVERRUNNING
SOLENOID "B" - OFF
THIRD CLUTCH - APPLIED NOT EFFECTIVE
FORWARD BAND - APPLIED
TCC SOLENOID - ON
THIRD ROLLER CLUTCH - OVERRUNNING
FOURTH CLUTCH - APPLIED

To obtain fourth gear, the PCM receives input signals from the Vehicle Speed Sensor (VSS) and Throttle Position Sensor (TPS) in order to "energize" by providing a ground for solenoid "A" (315). When energized, line pressure is directed into the solenoid "A" passage to the 3-4 shift valve (362). Solenoid "A" pressure shifts the valve against spring pressure allowing 3rd fluid to enter the 4th and 4th clutch fluid passages. 4th fluid is directed to:
^ the 4th clutch discrete pressure switch (218) to close the switch
^ seats #10 checkball (372) to force the fluid through a feed orifice to stroke the 3-4 accumulator piston (428) while applying the 4th clutch 3-4 accumulator fluid on the spring side of the piston is forced through the 3-4 accumulator pin (426) into the 3-4 accumulator passage and exhausts at the 3-4 accumulator valve (350).

Solenoid "A" (315): Energizes to prevent fluid from exhausting out of the line passage and solenoid "A" passage.

1-2 Shift Valve (318): Is held against solenoid "A" by spring pressure and solenoid "B" off fluid pressure at the end of the valve.

3-4 Shift Valve (362): When shifted against spring force, it allows 3rd fluid to enter the 4th and 4th clutch fluid passages. 4th fluid seats #10 checkball (372) and is forced through a feed orifice before stroking the 3-4 accumulator piston (428) and applying the fourth clutch.

4th Clutch Discrete Switch (218): A normally open switch that closes when 4th fluid pressure is fed from the 3-4 shift valve (362). When the switch is closed it completes the circuit from the PCM to ground and provides information to the PCM that the transaxle is in Overdrive Range - Fourth Gear.

#10 Checkball (372): Located in the valve body (300), it forces 4th fluid through a feed orifice into the 4th clutch passage to stroke the 3-4 accumulator piston (428).

3-4 Accumulator Piston (428): Cushions the apply of the 4th clutch by using 4th clutch fluid to stroke the piston against spring force and 3-4 accumulator fluid.

-4 Accumulator Valve (350): Controls the rate of exhaust of 3-4 accumulator fluid during 4th clutch apply.