Description and Operation Part 2

Part 2







Accumulator Body





The accumulator body is on the torque converter housing, next to the main valve body. It contains the 1st and 2nd accumulators, and the lubrication check valve.

HYDRAULIC FLOW





As the engine turns, the ATF Pump also starts to operate. Automatic transmission fluid (ATF) is drawn through the ATF strainer (filter) and discharged into the hydraulic circuit. Then, ATF flowing from the ATF pump becomes line pressure that's regulated by the regulator valve. Torque converter pressure from the regulator valve enters the torque converter through the lock-up shift valve, and it is discharged from the torque converter. The torque converter check valve prevents torque converter pressure from rising.
The TCM controls the shift control solenoid valves on and off, and the shift control solenoid valves apply shift control solenoid pressure to the shift valves. Applying shift control solenoid pressure to the shift valves moves the position of the shift valve and switches the port of hydraulic pressure. The TCM also controls the A/T clutch pressure control solenoid valves A and B. The A/T clutch pressure control solenoid valves regulate A/T clutch solenoid pressure and apply A/T clutch pressure control solenoid pressure to the CPC valves A and B.
When shifting between upper gear and lower gear, the clutch is engaged by pressure from the CPC pressure mode. The TCM controls one of the shift control solenoid valves to move the position of the shift valve. This movement switches the port of the CPC and line pressure. Line pressure is then applied to the clutch, and CPC pressure is intercepted. Engaging the clutch with line pressure happens when shifting is completed.

[N] Position





The TCM controls the shift control solenoid valves. The conditions of the shift control solenoid valve and positions of the shift valve are as follows:
- Shift control solenoid valve A is turned off, and the shift valve A is moved to the left side.
- Shift control solenoid valve B is turned on, and the shift valve B remains in the right side.
- Shift control solenoid valve C is turned off, and the shift valve C remains in the left side.
Line pressure (1) passes through the manual valve and stops at the shift valve D. Line pressure (1) also flows to the modulator valve, and becomes modulator pressure (6). Modulator pressure (6) flows to the shift control solenoid valves and the A/T clutch pressure control solenoid valves. Under this condition, hydraulic pressure is not applied to the clutches.

[D4] Position





1. 1st gear shifting from [N] position
The TCM turns shift control solenoid valves A and C on when shifting to [D4] position from [N]. Shift control solenoid valve B remains on. Shift control solenoid valve C is turned on, and SH C pressure (SC) in the right side of shift valve C is released, then shift valve C is moved to the right side. The shift control solenoid valve A is turned on, and SH A pressure (SA) in the left side of shift valve A is released, then shift valve A is moved to the right side. The A/T clutch pressure control solenoid valve A regulates LS A pressure (56), and applies it to the CPC valve A. Line pressure (1) becomes line pressure (4) at the manual valve, and flows to the shift valve C and the CPC valve A. Line pressure (4A) becomes CPC A pressure (4A) and passes through the shift valve C, A and B, then CPC A pressure (4A) becomes 1st clutch pressure (10) at shift valve B. 1st clutch pressure (10) is applied to the 1st clutch, then the 1st clutch is engaged with pressure of the CPC pressure mode. Line pressure (4) passes through shift valve A and 8, and stops at shift valve B.





2. Driving in 1st gear
The TCM turns shift control solenoid valve A off, but shift control solenoid valves B and C remain on. SH A pressure (SA) is applied to the left side of shift valve A, then shift valve A is moved to the left side. This movement switches the port of line pressure and CPC pressure on shift valve A. The 1st clutch pressure is changed to line pressure mode, and the 1st clutch is engaged securely. The CPC A pressure (5E) stops at shift valve B.





3. Shifting between 1st gear and 2nd gear
As the speed of the vehicle reaches the prescribed value, the TCM turns shift control solenoid valve A off. Shift control solenoid valves B and C remain on. Then shift control solenoid valve A is turned on, and SH A pressure (SA) in the left side of the shift valve A is released. Shift valve A is moved to the right side to switch the port of line pressure and CPC pressure. The TCM also controls the A/T clutch pressure control solenoid valves. The A/T clutch pressure control solenoid valves A and B apply their pressure to the CPC valves A and B. Line pressure (4) becomes CPC B pressure (4B) at the CPC valve B, and CPC B pressure passes through shift valves C, B, and A, to become 2nd clutch pressure. The 1st and 2nd clutches are engaged with the CPC pressure mode,





4. Driving in 2nd gear
The TCM turns shift control solenoid valve C off, and controls A/T clutch pressure control solenoid valve A to release LS A pressure (56). The shift control solenoid valves A and B remain on. Releasing LS A pressure in the CPC valve A releases CPC A pressure in the 1st clutch pressure circuit. Shift control solenoid valve C is turned off, and SH C pressure (SC) is applied to the right side of it. Then shift valve C is moved to the left side to switch the port of line pressure and CPC pressure. The 2nd clutch pressure is changed to line pressure mode, and the 2nd clutch is engaged securely. The CPC B pressure (5D) stops at shift valve B.





5. Shifting between 2nd gear and 3rd gear
As the speed of the vehicle reaches the prescribed value, the TCM turns shift control solenoid valve B off. The TCM also controls A/T clutch pressure control solenoid valve A to apply LS A pressure (56) to the CPC valve A. Shift control solenoid valve A remains on, and C remains off. Shift control solenoid valve B is turned off, and SH B pressure (SB) is applied to the right side of shift valve B. Then shift valve B is moved to the left side to switch the port of line pressure and CPC pressure. Line pressure (4) becomes CPC A pressure (4A) at the CPC valve A. The CPC A pressure (4A) becomes 3rd clutch pressure (30) at shift valve B, and flows to the 3rd clutch. The 2nd clutch pressure is changed to CPC pressure mode by switching the position of shift valve B.





6. Driving in 3rd gear
The TCM turns shift control solenoid valve C on, and controls A/T clutch pressure control solenoid valve B to release LS B pressure (57). Shift control solenoid valve A remains on, and B remains off. Releasing LS B pressure in the CPC valve B releases CPC B pressure in the 2nd clutch pressure circuit. Shift control solenoid valve C is turned on, and SH C pressure (SC) in the right side of shift valve C is released. Then shift valve C is moved to the right side to switch the port of line pressure and CPC pressure. 3rd clutch pressure is changed to line pressure mode, and the 3rd clutch is engaged securely. The CPC A pressure (4A) stops at shift valve E.





7. Shifting between 3rd gear and 4th gear
As the speed of the vehicle reaches the prescribed value, the TCM turns shift control solenoid valve A off. The TCM also controls A/T clutch pressure control solenoid valve B to apply LS B pressure (57) to CPC valve B. Shift control solenoid valve B remains off, and C remains on. Shift control solenoid valve A is turned off, and SH A pressure (SA) is applied to the left side of shift valve A. Then shift valve A is moved to the left side to switch the port of line pressure and CPC pressure. Line pressure (4) becomes CPC B pressure (4B) at CPC valve B. The CPC B pressure (4B) becomes 4th clutch pressure (41) at shift valve D, and flows to the 4th clutch via the manual valve. The 3rd clutch pressure is changed to CPC pressure mode by switching the position of shift valve A.





8. Driving in 4th gear
The TCM turns shift control solenoid valve C off, and controls A/T clutch pressure control solenoid valve A to release LS A pressure (56). Shift control solenoid valves A and B remain off. Releasing LS A pressure (56) releases CPC A pressure in the 3rd clutch pressure circuit. Shift control solenoid valve C is turned off, and SH C pressure (SC) is applied to the right side of shift valve C. Then shift valve C is moved to the left side to switch the port of line pressure and CPC pressure. The CPC B pressure (5B) changes to line pressure (5B) at shift valve C, and flows to the 4th clutch via shift valve C, shift valve B, shift valve D, and the manual valve. The 4th clutch pressure is changed to line pressure mode by switching the position of shift valve A, shift valve C, and 4th clutch is engaged securely. The CPC B pressure (5D) stops at shift valve A.

[2] Position





The TCM controls the shift control solenoid valves and the A/T clutch pressure control solenoid valves. The conditions of the shift control solenoid valves and the positions of the shift valves are as follows:
- Shift control solenoid valve A is turned on, and shift valve A is in the right side.
- Shift control solenoid valve B is turned on, and shift valve B is in the right side.
- Shift control solenoid valve C is turned off, and shift valve C is moved to the left side. The TCM also controls A/T clutch pressure control solenoid valve B to apply LS B pressure (57) to CPC valve B. Line pressure (4) from the manual valve becomes line pressure (5C) at shift valve C. Line pressure (5C) flows to shift valve A via shift valve B, and becomes 2nd clutch pressure (20). The 2nd clutch pressure is applied to the 2nd clutch, and 2nd clutch is engaged securely.

[1] Position





The TCM controls the shift control solenoid valves and the A/T clutch pressure control solenoid valves. The conditions of the shift control solenoid valves and the positions of the shift valves are as follows:
- Shift control solenoid valve A is turned off, and shift valve A is moved to the left side.
- Shift control solenoid valve B is turned on, and shift valve B is in the right side.
- Shift control solenoid valve C is turned on, and shift valve C is in the right side.
Line pressure (4) becomes line pressure (5B) at shift valve C. Line pressure (5C) flows to shift valve B via shift valve A, and becomes 1st clutch pressure (10). 1st clutch pressure (10) is applied to the 1st clutch, and 1st clutch is engaged securely.

[R] Position





1. Shifting to [R] position from [P]or [N] position
Line pressure (1) becomes line pressure (3) at the manual valve, and flows to the reverse CPC valve. Line pressure (3) is regulated by the reverse CPC valve and becomes line pressure (3'). Line pressure (Y) pushes the servo valve to the reverse position, passes through the servo valve, and flows to the manual valve. Line pressure (3') becomes 4th clutch pressure (40). The 4th clutch pressure (40) is applied to the 4th clutch, and 4th clutch is engaged with the reverse CPC pressure mode.





2. Driving in reverse gear
The TCM turns shift control solenoid valve C off. Shift control solenoid valve A remains off, and B remains on. Shift control solenoid valve C is turned off, and SH C pressure (SC) is applied to the right side of the reverse CPC valve. Then the reverse CPC valve moves to the left side and full the port leading to line pressure. Line pressure to the 4th clutch is the same as in [R] position, and 4th clutch pressure increases. The 4th clutch is engaged with line pressure mode.

[P] Position





Shift control solenoid valve C is turned off by the TCM, and SH C pressure (SC) is applied to the right side of the reverse CPC valve. Then the reverse CPC valve is moved to the left side to uncover the port leading line pressure (3) to the servo valve. Line pressure (3') passes through the servo valve and flows to the manual valve. Line pressure (3') is intercepted at the manual valve, and is not applied to the clutches.

LOCK-UP SYSTEM





In [D4] position and sequential sportshift mode (2nd, 3rd and 4th), and [D3] position (2nd and 3rd), pressurized fluid is drained from the back of the torque converter through a fluid passage, causing the lock-up piston to be held against the torque converter cover. As this takes place, the mainshaft rotates at the same speed as the engine crankshaft. Together with hydraulic control, the TCM optimizes the timing of the lock-up mechanism. When the lock-up control solenoid valve activates, modulator pressure changes to switch lock-up on and off. The lock-up control valve and the lock-up timing valve control the range of lock-up according to A/T clutch pressure control solenoid valves A and B. The lock-up control solenoid valve is mounted on the torque converter housing, and A/T clutch pressure control solenoid valves A and B are mounted on the transmission housing. They are controlled by the TCM.
The table below shows the lock-up conditions for lock-up control solenoid valve and A/T clutch pressure control solenoid A or B pressure.

Lock-Up Clutch





1. Operation (clutch on)
With the lock-up clutch on, fluid in the chamber between the torque converter cover and the lock-up piston is drained off, and the converter fluid exerts pressure through the piston against the torque converter cover. As a result, the converter turbine is locked to the converter cover. The effect is to bypass the converter, placing the vehicle in direct drive.





2. Operation (clutch off)
With the lock-up clutch off, fluid flows in the reverse of CLUTCH ON. As a result, the lock-up piston moves away from the converter cover, and torque converter lock-up is released.

No Lock-Up





The lock-up control solenoid valve is turned off by the TCM.
The lock-up shift valve receives LC pressure (LA) on the left side, and modulator pressure (6) on the right side. The lockup shift valve is in the right side to uncover the port leading torque converter pressure (92) to the left side of the torque converter. Torque converter pressure (92) becomes torque converter pressure (94), and enters into the left side of the torque converter (to disengage the lock-up clutch). The lock-up clutch is OFF.

NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.

Partial Lock-up





As the speed of the vehicle reaches the prescribed value, the lock-up control solenoid valve is turned on by the TCM to release LC pressure (LA) in the left side of the lock-up shift valve. The lock-up shift valve is moved to the left side to switch the port leading torque converter pressure to the left side and right side of the torque converter. Torque converter pressure (92) flows to the right side of the torque converter to engage the lock-up clutch. The TCM also controls A/T clutch pressure control solenoid valves A and B, and LS A or LS B pressure is applied to the lock-up control valve and the lock-up timing valve. The position of the lock-up control valve depends on torque converter pressure and LS A or LS B pressure. When LS A or LS B pressure (58) is lower, torque converter pressure (92) from the regulator valve passes through the lock-up control valve, and flows to the left side of the torque converter to disengage the lock-up clutch. Under this condition, the torque converter receives pressure from the right side (to engage the lock-up clutch) and the left side (to disengage the lock-up clutch); the lock-up clutch is in partial lock-up condition.

NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.

Half Lock-up





As the speed of the vehicle reaches the prescribed value, the TCM controls A/T clutch pressure control solenoid valves A and B. Higher LS A or LS B pressure (58) is applied to the lock-up control valve to release torque converter back pressure (F2). Torque converter back pressure (F2) goes lower, and this allows a greater amount of pressure (F1) to work on the lock-up clutch to engage the lock-up clutch. Back pressure (F2), which still exists, prevents the clutch from fully engaging.

NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.

Full Lock-up





When the vehicle speed further increases, the TCM controls A/T clutch pressure control solenoid valves A and B to increase LS A or LS B pressure (58). The LS A or LS B pressure (58) is applied to the lock-up control valve and the lockup timing valve, and moves them to the left side. Under this condition, torque converter back pressure (F2) is fully released, causing the lock-up clutch to be fully engaged.

NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.

Deceleration Lock-up





When decelerating, the TCM controls the lock-up control solenoid valve and the A/T clutch pressure control solenoid valve A or B to activate the same as in half lock-up conditions. Medium LS A or LS B pressure (58) is applied to the lock-up control valve to release torque converter back pressure (F2). Torque converter back pressure (F2) goes lower, and this allows a greater amount of pressure (F1) to work on the lock-up clutch to engage the lock-up clutch. Back pressure (F2), which still exists, prevents the clutch from fully engaging.

NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.

SHIFT LEVER / SEQUENTIAL SPORTSHIFT MODE

Mechanism





The shift lever has eight positions: [P], [R], [N], [D4], [D3], [2], [1] positions, and the sequential sportshift mode position. The shift lever shifts between positions along the gate in the A/T gear position indicator panel. The shift lever can shift out of [P] position and in to [R] position without depressing the shift lever. The shift lock/reverse lock mechanism is an additional shift lever lockout mechanism.
The shift lever is engaged with the shift cable bracket in [P], [R], [N], [D4], [D3], [2], and [1] positions. This unit shifts the transmission using the shift cable connected between the shift cable bracket and the transmission control shaft.
In the sequential sportshift mode position, the shift lever is disengaged from the shift cable bracket, and the shift lever can be used to shift gears electronically with the mode switch between 1st through 4th, much like a manual transmission.





When the shift lever shifts to the sequential sportshift mode position, the shift lever releases the lock lever, and the lock lever pops up to engage the shift cable bracket to the detent bracket; the shift cable bracket and the shifting positions in the transmission are held in position.
The lock lever receives its spring load, pops up in the sequential sportshift mode position, and is depressed by the shift lever and does not engage the shift cable bracket to the shift lever base bracket in any position except sequential sportshift mode.





The shift lever has a detent plunger which receives the detent plunger spring load to fit in the sequential sportshift mode position. When shifting to upshift or downshift positions, the detent plunger is depressed by the detent bracket inner wall, and the detent plunger spring puts the shift lever back into the position. The detent plunger also works in [P] position.

LOCK MECHANISM
The shift lock system reduces the risk of unintentional engine starting. Starting the engine is possible only in the [P] and [N] positions. The shift lock system and the key interlock system are the interlock control system. The key interlock mechanism is located in the steering lock assembly. The shift lock mechanism consists of the shift lock solenoid, shift lock stop, shift lock release and related parts. The reverse lock mechanism shares the shift lock solenoid with the shift lock mechanism, and the reverse lock stop and the shift lock stop are interlocked with the shift lock solenoid operation. The shift lock solenoid is electronically controlled by these shift lock control system signals: brake switch signal, interlock control signal, and A/T gear position switch [P] position signal. If the shift lock solenoid does not operate, the shift lock/reverse lock mechanism can be released by depressing the shift lock release.





In [P] position while depressing the brake pedal, the shift lock solenoid is turned ON, and the shift lock solenoid plunger is retracted to release the shift lock stop. This allows the shift lever to be moved from [P] position.





When the shift lever is shifted to [R] position from [D4] position and [N] position (under certain conditions), the shift lock solenoid is turned ON, and the shift lock solenoid plunger is retracted to release the reverse lock stop. This allows the shift lever to be moved to [R] position.





When the brake pedal is released, the shift lock solenoid remains OFF, and the shift lock stop locks to block the shift lever in the [P] position.





If the allowable conditions of turning ON the solenoid are not met, the shift lock solenoid remains OFF, and the reverse lock stop locks to block the shift lever in the [N] position.