LEXUS SC400 1991 Service Repair Manual

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
±
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
±
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\
 
\

\
Vernier calipers
 

Check length of second coast brake
piston rod.
\
 
\

\
Dial indicator or dial indicator with magnetic baseCheck piston stroke and end play of
the output shaft.
\
 
\

\
Dial indicator with magnetic baseCheck inside diameter of major
bushing.
\
 \
Straight edgeCheck side clearance of oil pump.
\
 \
Torque wrench
\
 
\

\
Cylinder gaugeCheck inside diameter of the trans-
mission case rear bushing.
\
 \
Voltmeter
\
 \
Ammeter(A)
\
 \
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
\
 \
08826±00090 Seal Packing 1281, Transmission case X Oil pan
\
 
\

\

THREE BOND 128\
1 or equivalentTransmission case X Extension
housing
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION PREPARATIONAT±13
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ON±VEHICLE REPAIR
AT06Y±04
CAUTION: Work must be started after 90 seconds from
the time the ignition switch is turned to the ªLOCKº posi-
tion and the negative (±) terminal cable is disconnected
from the battery.
EXTENSION HOUSING
EXTENSION HOUSING REAR OIL SEAL
REPLACEMENT
AT0QW±01
1. DRAIN ATF
2. REMOVE FRONT EXHAUST PIPE AND HEAT INSULATOR
(See pages EG±204)
3. REMOVE PROPELLER SHAFT (See pages PR±6)
4. REMOVE TRANSMISSION OUTPUT FLANGE
(a) Using a hammer and chisel, loosen the staked part of the nut.
HINT: Shift the shift lever to the P position.
(b) Using SST, remove the nut.
SST 09060±20100
(c) Tap the output flange with a plastic hammer to remove it and 2 washers.
(d) Using a screwdriver, remove the oil seal from the output flange.
5. REMOVE EXTENSION HOUSING REAR OIL SEAL Using SST, remove the oil seal.
SST 09308±00010
AT±14
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION EXTENSION HOUSING
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6. INSTALL EXTENSION HOUSING REAR OIL SEAL
(a) Coat the lip of oil seal with MP grease.
(b) Using SST and a hammer, drive in a new oil seal with the lipfacing downward.
SST 09309±37010
Oil seal depth from flat end:
0±0.3 mm (0±0.012 in.)
7. INSTALL TRANSMISSION OUTPUT FLANGE
(a) Using SST and a hammer, drive in a new oil seal.SST 09517±36010
(b) Install the output flange and 2 washers.
(c) Using SST, install and torque a new nut. SST 09060±20010
Torque: 123 N Vm (1,250 kgf Vcm, 90 ft Vlbf)
HINT: Shift the shift lever to the P position.
(d) Using a hammer and chisel, stake the nut.
8. INSTALL PROPELLER SHAFT (See pages PR±12)
9. INSTALL FRONT EXHAUST PIPE AND HEAT INSULATOR (See page EG±204)
10. FILL WITH ATF
11. CHECK FLUID LEVEL (See page AT±47)
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A304E (1UZ±FE) AUTOMATIC TRANSMISSION EXTENSION HOUSINGAT±15
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SPEED SENSOR
NO.1 VEHICLE SPEED SENSOR
REPLACEMENT
(w/ Speedometer Driven Gear)
AT070±04
1. REMOVE TRANSMISSION CONTROL ROD REAR SIDERemove the transmission control rod rear side set nut.
2. DISCONNECT NO.1 VEHICLE SPEED SENSOR CONNECTOR
3. REMOVE NO.1 VEHICLE SPEED SENSOR ASSEMBLY
(a) Remove the bolt and No.1 vehicle speed sensor assembly.
(b) Remove the speedometer driven gear from No.1 vehicle
speed sensor.
(c) Remove the O±ring from No.1 vehicle speed sensor.
4. INSPECT NO.1 VEHICLE SPEED SENSOR
(See page AT±78)
5. INSTALL NO.1 VEHICLE SPEED SENSOR ASSEMBLY
(a) Coat a new O±ring with ATF and install it to the speed sensor.
(b) Install the speedometer driven gear to the speed sensor.
(c) Install the No.1 vehicle speed sensor assembly and torque the bolt.
Torque: 16 N Vm (160 kgf Vcm, 12 ft Vlbf)
6. CONNECT NO.1 VEHICLE SPEED SENSOR
CONNECTOR
7. INSTALL TRANSMISSION CONTROL ROD REAR SIDE
8. INSPECT AND ADJUST SHIFT LEVER POSITION (See page AT±48)
AT±16
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A304E (1UZ±FE) AUTOMATIC TRANSMISSION SPEED SENSOR
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NO.2 VEHICLE SPEED SENSOR
REPLACEMENT
AT0GF±02
1. DISCONNECT NO.2 VEHICLE SPEED SENSORCONNECTOR
2. REMOVE NO.2 VEHICLE SPEED SENSOR
(a) Remove the bolt and No.2 vehicle speed sensor.
(b) Remove the O±ring from it.
3. INSPECT NO.2 VEHICLE SPEED SENSOR (See page AT±86)
4. INSTALL NO.2 VEHICLE SPEED SENSOR
(a) Cost a new O±ring with ATF and install it to the speed sensor.
(b) Install the speed sensor and torque the bolt.
Torque: 5.4 N Vm (55 kgf Vcm, 48 in. Vlbf)
5. CONNECT NO.2 VEHICLE SPEED SENSOR
CONNECTOR
O/D DIRECT CLUTCH SPEED SENSOR
REPLACEMENT
AT072±04
1. REMOVE FRONT EXHAUST PIPE AND LH SIDECATALYTIC CONVERTER
(See pages EG±204)
2. REMOVE LH SIDE HEAT INSULATORS
3. DISCONNECT O / D DIRECT CLUTCH SPEED SENSOR CONNECTOR
4. REMOVE O/D DIRECT CLUTCH SPEED SENSOR
(a) Remove the bolt and O/D direct clutch speed sensor.
(b) Remove the O±ring from it.
5. INSPECT O/D DIRECT CLUTCH SPEED SENSOR (See page AT±98)
6. INSTALL O/D DIRECT CLUTCH SPEED SENSOR
(a) Coat a new O±ring with ATF and install it to the O/D direct clutch speed sensor.
(b) Install the O/D direct clutch speed sensor and torque the bolt.
Torque: 5.4 N Vm (55 kgf Vcm, 48 in. Vlbf)
7. CONNECT O/D DIRECT CLUTCH SPEED SENSOR
CONNECTOR
8. INSTALL LH SIDE HEAT INSULATORS
9. INSTALL LH SIDE CATALYTIC CONVERTER AND FRONT EXHAUST PIPE
(See page EG±204)
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A304E (1UZ±FE) AUTOMATIC TRANSMISSION SPEED SENSORAT±17
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