Overdrive Range, Third Gear - Torque Converter Clutch (TCC) Not Applied (Without Driver Shift Control) through Case Fluid Passa

Description and Operation

Overdrive Range, Second Gear - Without Driver Shift Control

Overdrive Range, Third Gear - Torque Converter Clutch (TCC) Not Applied (Without Driver Shift Control)
As vehicle speed increases and operating conditions become appropriate, the PCM energized the 2-3 shift solenoid valve in order to shift the transmission into Third gear. The manual valve remains in the Overdrive (D) position, and line pressure continues to feed the drive and the PRND4 fluid circuits.

Direct Clutch Applies

2-3 Shift Solenoid Valve
The PCM energizes the normally open 2-3 shift solenoid valve, which blocks the 2-3 signal fluid from exhausting. The 2-3 signal fluid pressure is routed to both of the 1-2 and 2-3 shift valves.

2-3 Shift Valve
The 2-3 signal fluid pressure moves the valve against a spring force in order to initiate the 2-3 upshift. The 2-3 drive fluid is routed through the valve and into the 3-4 drive fluid circuit.

#5 Checkball (Direct Clutch Apply)
The 3-4 drive fluid pressure seats the #5 checkball, and 3-4 drive fluid is forced through the #26 orifice and into the direct clutch feed fluid circuit. The #26 orifice helps to control the direct clutch apply.

Direct Clutch
The direct clutch fluid pressure applies the direct clutch, causing the transmission to shifts into Third gear.

3-4 Shift Valve
The 3-4 drive fluid is also routed to the 3-4 shift valve in preparation for a 3-4 upshift.

Shift Accumulation

2-3 Accumulator
Direct clutch feed fluid is also routed to the 2-3 accumulator piston. This fluid pressure moves the piston against a combination of spring force and the 2-3 accumulator feed fluid pressure. This action absorbs the initial direct clutch fluid pressure in order to cushion the direct clutch apply. the movement of the 2-3 accumulator piston forces some of the fluid out of the accumulator.

Torque Converter Clutch (TCC)

Torque Converter Clutch (TCC)
Under normal operating conditions the TCC is released in Third gear. However the TCC apply could vary depending upon the vehicle application, and the TCC may be calibrated in order to apply in Overdrive Range - Third gear.

A/T Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) Assembly
Release fluid pressure routed to the TFP Val. Position Sw. Assembly signals to the PCM that the TCC is released.

Overdrive Range, Third Gear - TCC Not Applied - Without Driver Shift Control

Overdrive Range, Fourth Gear - Torque

Converter Clutch (TCC) Applied (Without Driver Shift Control)
When operating conditions are appropriate, the PCM energizes the 1-2 shift solenoid valve in order to shift the transmission into Fourth gear. In addition, the TCC is applied in Fourth gear. The manual valve remains in the Overdrive position and line pressure continues to feed the Drive and the PRND4 fluid circuits.

Intermediate and Fourth Band Applied

1-2 Shift Solenoid Valve
The PCM energizes the normally open 1-2 shift solenoid valve, which blocks the 1-2 signal fluid from exhausting. The 1-2 signal fluid pressure is routed to both the 1-2 and the 3-4 shift valves.

1-2 Shift Valve
The 1-2 signal fluid pressure does not affect the 1-2 shift valve. A combination of spring force and the 2-3 signal fluid pressure keeps the 1-2 shift valve in the upshifted position.

3-4 Shift Valve
The 1-2 signal fluid pressure moves the valve against a spring force and into the Fourth gear position. The 3-4 drive fluid is routed into the fourth band fluid circuit.

Intermediate and Fourth Servo
The 1-2 signal fluid pressure moves the valve against a spring force and into the Fourth gear position. The 3-4 drive fluid is routed into the fourth band fluid circuit.

Shift Accumulation

3-4 Accumulator
The fourth band fluid is also routed to the 3-4 accumulator piston. Fourth band fluid pressure moves the piston against a combination of spring force and 3-4 accumulator feed fluid pressure. This action absorbs initial fourth band fluid pressure in order to cushion the intermediate and Fourth band apply. The movement of the 3-4 accumulator piston forces some fluid out of the accumulator.

3-4 Accumulator Valve
The 3-4 accumulator feed fluid which is forced from the 3-4 accumulator unseats the #7 checkball and the fluid is routed back to the 3-4 accumulator valve. This pressure forces the 1-2/3-4 accumulator valve against a combination of spring force and torque signal fluid pressure in order to regulate the exhaust of excess accumulator fluid. This regulation provides additional control for the intermediate and fourth band apply.

Torque Converter Clutch Applied

TCC Control Solenoid Valve
When conditions are appropriate, the PCM energized the TCC control solenoid valve in order to initiate the TCC apply. The solenoid valve is Pulse Width Modulated (PWM) in order to provide a smooth TCC apply (Refer to the electrical controls section for a detailed description of the TCC control solenoid valve operation). When energized, the solenoid valve modulates the filtered 2-3 drive fluid into the TCC signal fluid circuit.

TCC Regulated Apply Valve
TCC Signal fluid pressure modulates the valve against a combination of spring force and TCC regulated apply fluid pressure. This action directs line pressure into the TCC regulated apply fluid circuit in relation to vehicle operating conditions.

TCC Control Valve
Modulated TCC signal fluid pressure moves the valve against a spring force in relation to vehicle operating conditions. This action regulates TCC regulated apply fluid into the apply fluid circuit. At the same time, the release fluid circuit is opened to an orificed exhaust. In this position the valve directs TCC feed limit fluid in order to feed the cooler fluid circuit.

Torque Converter Clutch (TCC)
Apply fluid is routed to the torque converter at the same time that release fluid exhausts from the converter. Apply fluid pressure applies the TCC.

A/T Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) Assembly
Release fluid also exhausts from the TFP Val. Position Sw. Assembly, which signals to the PCM that the TCC is released.

Overdrive Range, Fourth Gear - TCC Applied - Without Driver Shift Control

Overdrive Range, 4-3 Downshift - Torque Converter Clutch (TCC) Not Applied (Without Driver Shift Control)
When the transmission is operating in Overdrive Range - Fourth Gear, a forced 4-3 downshift will occur following a significant increase in throttle position. At minimum throttle, vehicle speed will decrease gradually (coastdown) and the PCM will command a 4-3 downshift. The PCM will also initiate a 4-3 downshift if the engine load is increased while the throttle position remains the same (for example, driving up a steep hill).

Line Pressure Increases

Pressure Control Solenoid (PCS) Valve
During the downshift, except for a coastdown, the PCM senses the increase in the throttle position or the engine load. When this occurs the PCM increases the PCS duty cycle. The increase in duty cycle increases the output fluid pressure from the PCS, thereby increasing the torque signal fluid pressure at the torque signal regulator valve.

Pressure Regulator Valve
Increased torque signal fluid pressure acting on the boost valve increases line pressure at the pressure regulator valve.

Intermediate and Fourth Band Releases

1-2 Shift Solenoid Valve
The PCM de-energizes the normally open solenoid valve and the 1-2 signal fluid exhausts.

3-4 Shift Valve
The 1-2 signal fluid pressure exhausts from the 3-4 shift valve and a spring force moves the valve into the Third gear position. This opens the Fourth band fluid circuit to an orificed exhaust in order to help control the band release.

Intermediate and Fourth Servo
Fourth band fluid exhausts from the servo and a spring force moves the servo to the release position, thereby releasing the band.

3-4 Accumulator
The fourth band fluid exhausts from the accumulator. A combination of spring force and 3-4 accumulator feed fluid pressure moves the accumulator piston to the Third gear position.

1-2/3-4 Accumulator Valve
The accumulator valve regulates line pressure into the 1-2/3-4 accumulator fluid circuit in order to fill the 3-4 accumulator. Torque signal fluid pressure controls this regulation. Increased torque signal fluid pressure regulates accumulator fluid to a higher pressure.

Torque Converter Clutch
The PCM commands TCC release prior to initiating a 4-3 downshift. When the TCC is in the release position, release fluid pressure is routed to the pressure switch assembly. This fluid pressure signals the PCM that the TCC is in the release position. The TCC is not applied under normal operating conditions in Third gear.

Overdrive Range, 4-3 Downshift - TCC Not Applied - Without Driver Shift Control

Drive Range, Manual Third (from Overdrive Range) (Without Driver Shift Control)

Important: The operating states for the shift solenoids follow the normal operation depending on vehicle driving conditions

A manual 4-3 downshift is accomplished by moving the gear selector lever to the Manual Third (3) position. In Manual Third the transmission is hydraulically prevented from upshifting into Fourth gear under any conditions. Also, the coast clutch is applied in all manual ranges in order to provide engine compressing braking whenever appropriated. The following information explains the additional changes during a Manual 4-3 downshift as compared to a forced 4-3 downshift. Refer to Overdrive Range, 4-3 Downshift - Torque Converter Clutch (TCC) Not Applied (Without Driver Shift Control) for a complete description of a 4-3 downshift.

Fourth Gear Hydraulically Prevented

Manual Valve
The manual valve moves into the Manual Third (3) position and line pressure enters the D321 fluid circuit. Also the manual valve blocks line pressure from the PRND4 fluid circuit and the PRND4 fluid exhausts past the manual valve.

3-4 Shift Valve
D321 fluid pressure assists a spring force in order to keep the valve in the Third gear position under any conditions. this opens the Forth band fluid circuit to an orificed exhaust and the Intermediate and Fourth band releases, thereby preventing Fourth gear.

A/T Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) Assembly
PRND4 fluid exhausts from the TFP Val. Position Sw. Assembly, which signals to the PCM that the manual valve is in the Manual Third position.

Manual Third-Second and First Gears
The transmission operates the same in Manual Third as in Overdrive range with the exception that Fourth gear is prevented. The transmission will upshift and downshift between First, Second, and Third gears as in Overdrive range. However, engine compression braking is not available in Manual Third - First and Second gears, and the vehicle will coast when you release the throttle.

Drive Range, Manual 3rd (from Overdrive Range) - Without Driver Shift Control

Drive Range, Manual Second (from Drive, Manual Third) (Without Driver Shift Control)
A manual 3-2 downshift is initiated by moving the gear selector lever to the Manual Second (2) position. However, the transmission will not downshift into Second gear until vehicle speed is below approximately 99 km/h (62 mph). At higher vehicle speeds the PCM will keep the 2-3 shift solenoid energized (On) and the transmission will operate in Manual Second - Third Gear as a safety precaution. In Manual Second the transmission is hydraulically prevented from upshifting into Fourth gear under any conditions. Also, the coast clutch remains applied as in Manual Third, and the clutch provides engine compression braking in the Third and the Second gears. The transmission upshifts and downshifts between First and Second gears as in Overdrive gear.

Manual Valve
Line pressure is routed into the D21 fluid circuit when the selector lever is moved into the Manual Second (2) position. Line pressure continues to feed the D321 fluid circuit as in Manual Third.

2-3 Shift Solenoid Valve
The PCM de-energized the 2-3 shift solenoid valve when the vehicle operating conditions are appropriate for a 3-2 downshift. With the solenoid valve Off, a 2-3 signal fluid exhausts through the 2-3 shift solenoid valve.

2-3 Shift Valve
A spring force moves the 2-3 shift valve into the Second gear position when the 2-3 signal fluid exhausts. The D21 fluid continues through the valve and the fluid is also routed into the intermediate band feed fluid circuit. The 3-4 drive fluid, which feeds the direct clutch, exhausts past the 2-3 shift valve.

Direct Clutch Releases

Direct Clutch
The direct clutch fluid exhausts and the direct clutch releases.

#6 Checkball (Direct Clutch Release)
Exhausting direct clutch fluid seats the #6 checkball. This fluid is forced through the #25 orifice in order to help to control the direct clutch release.

2-3 Accumulator
Direct clutch feed fluid exhausts from the 2-3 accumulator, unseats the #5 checkball, and exhausts past the 2-3 shift valve. The 2-3 accumulator feed fluid fills the 2-3 accumulator as the direct clutch feed fluid exhausts.

Intermediate and Fourth Band Applies
1-2 Shift Valve
The 1-2 shift solenoid valve is Off when the PCM commands the Second gear. A spring force holds the 1-2 shift valve in the upshifted position. Intermediate band feed fluid is routed through the valve and into the intermediate band fluid circuit.

#3 Checkball (Intermediate Band Apply)
Intermediate band fluid pressure seats the #3 checkball and is forced through the #8 orifice. This orifice helps to control the intermediate band apply.

Intermediate and Fourth Servo
Intermediate band fluid pressure is routed to the inner area of the intermediate and Fourth servo piston. This fluid pressure moves the servo piston and apply pin in order to apply the intermediate and Fourth band. The band provides engine compression braking in Manual Second - Second Gear.

Pressure Control
A/T Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) Assembly
The D21 fluid from the 2-3 shift valve is routed to the TFP Val. Position Sw. assembly, which signals to the PCM that the manual valve is in the Manual Second position.

Pressure Control Solenoid Valve
The PCM increases the PCS duty cycle in order to increase the operating range of torque signal fluid pressure in Manual Second. This provides increased line pressure for the additional torque requirements during engine compression braking and increased engine load in Manual Second.

Torque Converter Clutch
The PCM will release the TCC before downshifting into Manual Second. The TCC will not reapply in Second gear under normal operating conditions.

Drive Range, Manual 2nd (from Drive, Manual 3rd) - Without Driver Shift Control

Drive Range, Manual First (from Drive, Manual Second) (Without Driver Shift Control)

Important: As a safety feature, Manual First-Third Gear is also possible at high speeds.

A manual 2-1 downshift is initiated by moving the gear selector lever to the Manual First (1) position. However, the transmission will not downshift into First gear until the vehicle speed is below approximately 60 km/h (37 mph). At higher vehicle speeds the PCM will keep the 1-2 shift solenoid valve de-energized (Off) and the transmission will operate in Manual First - Second Gear. In Manual First the transmission is electronically prevented from upshifting into Third or Fourth gears under any conditions. Also, the coast clutch remains applied, as in Manual Third and Manual Second, and the clutch provides engine compression braking in First and Second gears.

Manual Valve
Line pressure is routed into the Low fluid circuit when the selector lever is moved into the Manual First (1) position. Line pressure continues to feed the Drive, the D321, and the D21 fluid circuits as in Manual Second.

A/T Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) Assembly
Low fluid pressure is routed to the TFP Val. Position Sw. Assembly, which signals to the PCM that the manual valve is in the Manual First position.

#1 Checkball (Low/PRN)
Low fluid pressure seats the #1 checkball against the PRN fluid circuit and this pressure fills the Low/PAN fluid circuit. Low/PAN fluid is routed to the 1-2 shift valve.

1-2 Shift Solenoid Valve
The PCM energizes the 1-2 shift solenoid valve when vehicle speed is below approximately 48 - 56 km/h (30 - 35 mph). The 1-2 signal fluid is blocked from exhausting through the solenoid valve.

1-2 Shift Valve
The 1-2 signal fluid pressure shifts the valve into the downshifted position against a spring force, and the following changes occur:
^ The 2-3 drive fluid circuit is open to an exhaust past the valve
^ The intermediate band fluid is exhausted past the valve
^ the Lo/PRN fluid is routed into the low band fluid circuit

Second Clutch Releases

Second Clutch
The Second clutch fluid exhausts from the clutch piston and through the 2-3 drive fluid circuit. This releases the Second clutch, and the transmission operates in First gear.

1-2 Accumulator
Second clutch feed fluid exhausts from the 1-2 accumulator, and the fluid exhausts past the #2 checkball and through the 2-3 drive fluid circuit. The 1-2 accumulator feed fluid fills the 1-2 accumulator as the second clutch fluid exhausts.

1-2/3-4 Accumulator Valve
The accumulator valve regulates the line pressure into the 1-2/3-4 accumulator fluid circuit in order to fill the 1-2 accumulator. Torque signal fluid pressure controls this regulation. Accumulator fluid pressure is regulated to a higher pressure with greater torque signal fluid pressure.

TCC Control Solenoid Valve
Filtered 2-3 drive fluid exhausts from the solenoid and through the 2-3 drive fluid circuit.

Intermediate Band Releases

Intermediate and Fourth Servo
Intermediate band fluid exhausts from the servo piston. A spring force moves the piston and the apply pin, and the intermediate and fourth band releases. However, the intermediate and fourth band remains applied in Manual First - Second Gear in order to achieve engine compression braking.

Low and Reverse Band Applies

Low and Reverse Servo
Low band fluid pressure is routed to the inner area of the Low and Reverse servo in order to apply the Low and Reverse band. The Low and Reverse band provides engine compression braking when the throttle is released in Manual First- First Gear.