1991 LEXUS SC400 automatic transmission

1. FUNCTION OF COMPONENTS AT±6
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A304E (1UZ±FE) AUTOMATIC TRANSMISSION OPERATION
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2. HYDRAULIC CONTROL SYSTEMThe hydraulic control system is composed of the oil pump, the valve body, the solenoid valves, the accumu-
lators, the clutches and brakes, as well as the fluid passages which connect al\
l of these components.
Based on the hydraulic pressure created by the oil pump, the hydraulic control system governs the hydrau-
lic pressure acting on the torque converter clutch, clutches and brakes \
in accordance with the vehicle driv-
ing conditions.
There are 4 solenoid valves on the valve body.
The No.1 and No.2 solenoid valves are turned on and off by signals from the ECM to operate the shift
valves, and change the gear shift position.
The No.3 solenoid valve is operated by signals from the ECM to engage or di\
sengage the lock±up clutch
of the torque converter clutch.
The No.4 solenoid valve is operated by signals from the ECM to control the \
engagement speed and reduce
gear shift shock.
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A304E (1UZ±FE) AUTOMATIC TRANSMISSION OPERATIONAT±7
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3. ELECTRONIC CONTROL SYSTEMThe electronic control system for the A340E automatic transmission provides\
extremely precise control of
the gear shift timing and lock±up timing in response to driving conditio\
ns as sensed by various sensors
located throughout the vehicle and in response to the engine's running condition.
At the same time, the ECM control reduces vehicle squat when the vehicle s\
tarts out and gear shift shock.
The electronic control system is also equipped with a self diagnosis sys\
tem which diagnoses malfunctions
of electronically controlled components and warns the driver, and a fail±safe system which makes it pos-
sible for the vehicle to continue functioning when a malfunction occurs.
CONSTRUCTION The electronic control system can be broadly divided onto 3 groups; the \
sensors, ECM and actuators.
AT±8±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION OPERATION
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SYSTEM DIAGRAM
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A304E (1UZ±FE) AUTOMATIC TRANSMISSION OPERATIONAT±9
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ARRANGEMENT COMPONENTS
AT±10±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION OPERATION
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PREPARATION
SST (SPECIAL SERVICE TOOLS)
AT06T±03
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A304E (1UZ±FE) AUTOMATIC TRANSMISSION PREPARATIONAT±11
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RECOMMENDED TOOLS
AT06U±04
AT±12±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION PREPARATION
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EQUIPMENT
AT06V±05\
 \
Feeler gauge Check major clearance\
 
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Vernier calipers
 

Check length of second coast brake
piston rod.
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Dial indicator or dial indicator with magnetic baseCheck piston stroke and end play of
the output shaft.
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Dial indicator with magnetic baseCheck inside diameter of major
bushing.
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Straight edgeCheck side clearance of oil pump.
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Torque wrench
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Cylinder gaugeCheck inside diameter of the trans-
mission case rear bushing.
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Voltmeter
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Ammeter(A)
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Ohmmeter
LUBRICANT
AT0GW±03
 Item Capacity Classification
 Automatic transmission fluid
 Dry fill 8.2 liters (8.7 US qts, 7.2 lmp. qts) ATF Type T±II or equivalent
 Drain and refill 1.9 liters (2.0 US qts, 1.7 lmp. qts) 
SSM (SPECIAL SERVICE MATERIALS)
AT06X±03
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 \
08826±00090 Seal Packing 1281, Transmission case X Oil pan
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THREE BOND 128\
1 or equivalentTransmission case X Extension
housing
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A304E (1UZ±FE) AUTOMATIC TRANSMISSION PREPARATIONAT±13
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