Overdrive Range Fourth Gear (Torque Converter Clutch Applied)

Overdrive Range - Fourth Gear (Converter Clutch Applied):

OVERDRIVE RANGE 4TH. GEAR (CONVERTER CLUTCH APPLIED)

To obtain fourth gear, the Powertrain Control Module (PCM) receives input signals from the Vehicle Speed Sensor (VSS), Throttle Position Sensor (TPS) and other engine sensors, to determine when to "energize" solenoid "A".

^ Manual Valve: In the Overdrive range fourth gear, line pressure from the pressure regulator valve is turned into PRND4, PRND43 and Drive fluid pressures. The PRND4 fluid pressure is directed to the Pressure Switch Manifold (PSM) and to the 2-3 shift valve, the PRND43 fluid is directed to the PSM and to the front servo, and the Drive fluid is directed to the PSM and forward clutch.
^ Pressure Switch Manifold (PSM): Drive, PRND4 and PRND43 fluid pressures from the manual valve are directed to the DR, PRND4 and PRND43 switches on the PSM, this sends a signal to the PCM that the transmission is in Overdrive range.
^ Solenoid "A": Energized, the signal "A" pressure forces the 3-4 against the spring force to move the 3-4 shift valve to the extreme left.
^ Solenoid "B": Energized, the signal "B" fluid pressure with spring force holds the 1-2 shift valve to the extreme right.
^ 1-2 Shift Valve: Held to the extreme right by signal "B" fluid pressure and spring force. Drive fluid pressure from the manual valve is changed into 2-3 drive fluid pressure at the 1-2 shift valve, this pressure is directed to the 2-3 shift valve, Pulse Width Motor (PWM) solenoid and the intermediate (second) clutch.
^ 2-3 Shift Valve: PRND4 fluid pressure from the manual valve is directed through the 2-3 shift valve (which turns into 4CLFD fluid pressure) to the 3-4 shift valve. 2-3DR fluid pressure from the 1-2 shift valve is changed into 3CLFD fluid pressure at the 2-3 shift valve, this fluid is directed to the #8 checkball which seats and forces the fluid through and orifice (where it becomes 3RD CL fluid pressure) and is directed to the third accumulator. 3CLFD fluid pressure is also directed to the #11 checkball which seats and forces the fluid through an orifice (which changes into 3RD REV fluid pressure) and to the direct clutch.
^ 3-4 Shift Valve: Is held to the extreme left by signal "A" fluid pressure. 4CLFD from the 2-3 shift valve is changed to 4TH CL fluid pressure at the 3-4 shift valve, 4TH CL fluid is directed to the #10 checkball which seats and forces the fluid through an orifice to apply the fourth clutch and fourth clutch accumulator.
^ Rear Servo: 2ND fluid pressure is supplied to the rear servo in the same manner as it is to the 2ND clutch. This fluid pressure is directed to the inner piston of the rear servo, thus applying the inner piston.
^ Forward Clutch: Is applied by Drive fluid pressure from the manual valve.
^ Direct Clutch: Third reverse pressure from the #11 checkball flows through the case and into the center support to apply the inner piston area of the direct clutch.
^ Intermediate (Second) Clutch: Is applied by 2ND fluid pressure from the 1-2 shift valve. 2-3 drive fluid pressure from the 1-2 shift valve seats the #4 checkball in the case and causes the fluid to flow through two orifices (which then becomes 2ND apply fluid pressure) into the center support which applies the intermediate (second) clutch.
^ Fourth Clutch: Fourth clutch pressure leaves the 3-4 shift valve and seats the #10 checkball, and causes the fluid to flow through an orifice, through the case into the fourth clutch housing which applies the fourth clutch. During the fourth clutch piston stroke, the transmission shifts into fourth gear.
^ Third Clutch Accumulator: 3RD CL fluid pressure is also applied to the third clutch accumulator which is encased in the accumulator housing. This moves the third accumulator piston against the spring force and accumulator fluid pressure.
^ Fourth Clutch Accumulator: Fourth clutch pressure is also supplied to the fourth clutch accumulator which is encased in the accumulator housing, this moves the fourth accumulator piston against the spring and accumulator pressure which smooths the 3-4 shift.
^ Pulse Width Modulated (PWM) Solenoid: When energized by the PCM signal pressure shifts the converter clutch shift valve, thus the [1][2]Torque Converter Clutch (TCC) is applied. The signal pressure also acts on the Torque Converter Clutch Regulator valve (TCCR) which regulates output pressure to control the apply and release of the TCC.