During Operation
Hydraulic pressure is applied to the reverse clutch piston from the control valve when shifting in reverse. The drive plate and driven plate are connected by this pressure, and engine power from the high clutch drum is transmitted to the front sun gear through the 2-4 brake hub.
Reverse Clutch Function During Operation. Scheme 1184
During Non-Operation
When the shift lever is in any position other than reverse, no hydraulic pressure is applied to the reverse clutch piston. Hence the drive plate and driven plate are separated, and no power is transmitted.
The check ball is built into the clutch piston. This check ball releases oil pressure from the clutch piston while the drum rotates idle. It thus avoids build-up of residual pressure in the clutch drum and a resultant half-engaged clutch, which may otherwise be caused by centrifugal oil pressure.
Reverse Clutch Function During Non-Operation. Scheme 1185
Non Lock-Up Operation
The Transmission Control Module (TCM) sends output signals to the lock-up duty solenoid. This causes the amount of ATF drained from the lock-up duty solenoid valve to be reduced, which increases the lock-up duty pressure.
The increased lock-up duty pressure moves the lock-up control valve upwards, connecting the torque converter regulator valve to the torque converter control valve release port.
Therefore, the oil pressure from the torque converter regulator valve flows through the lock-up control valve release port to the torque converter clutch and the torque converter apply circuit. As a result, the lock-up piston is forced to separate from the impeller cover, and power is transmitted from impeller to turbine to input shaft, as with an ordinary torque converter clutch coupling.
Lock-Up Control - Non Lock-Up Operation. Scheme 1186
Lock-Up Operation
The Transmission Control Module (TCM) sends output signal to the lock-up duty solenoid. Since the lock-up duty solenoid operates in proportion to the duty ratio, the amount of ATF drained from there is increased, thus lock-up duty pressure being reduced.
As a result, the lock-up control valve moves downward, which connects the torque converter regulator valve and the lock-up control valve apply port to each other.
In this condition, the oil pressure from the torque converter valve flows through the lock-up control valve apply port to the torque converter and the torque converter clutch. This causes a pressure differential across the lock-up piston. The piston is then forced against the impeller cover and turned as an integral unit with the cover. Thus, power from the engine is directly transmitted to the transmission input shaft. That is, the transmission is directly coupled to the engine.
Lock-Up Control - Lock-Up Operation. Scheme 1187
Smooth control
The lock-up duty solenoid is controlled by the TCM and controls the operation of the lock-up control valve. Because the lock-up operating pressure is controlled by the lock-up control valve, the force applied to the lock-up clutch is controlled for smooth clutch operation.
When locking up, the clutch is set in the half-engaged state beforehand. After this, the lock-up operating pressure is gradually increased to achieve smooth locking up.
Scheme 1188
- The oil pump delivery pressure (line pressure) is regulated to the constant pilot pressure by the pilot valve.
- The pilot pressure applied to the pressure modifier valve is regulated by the line pressure controlling line pressure duty solenoid and changed into the pressure modifier pressure.
- The pressure modifier valve is an auxiliary valve for the pressure regulator valve, and it creates a signal pressure (pressure modifier pressure) for regulating the line pressure to an optimum pressure corresponding to the driving conditions.
- This pressure modifier pressure is applied to the pressure regulator valve to control the oil pump delivery pressure.
- The pressure modifier pressure regulated by the pressure modifier valve is smoothed by the pressure modifier accumulator and pulsation in the line pressure is eliminated. (Scheme 1188): Line-Pressure Control
Oil pressure which engages shift clutches (to provide 1st through 4th speeds) is electronically controlled to meet varying operating conditions.
In other words, line pressure decreases to match the selected shift position, minimizing shifting shock.
Line-Pressure Shifting Control - Function. Scheme 1189
Operation Of Indicator Light
On starting the engine, AT OIL TEMP indicator light illuminates as shown below.
If any trouble occurs, the light continues flashing until ignition switch is turned to ON position (engine turned off).
