1991 LEXUS SC400 sensor

TORQUE SPECIFICATION
AT07F±04\
 \
Part tightened NVm kgf Vcm ft Vlbf\
 
\

\
Engine x Transmission
 

64
 

650
 

47
\
 \
Rear mounting x Body 25 260 19
\
 \
Rear mounting x Extension housing 25 250 18
\
 \
Transmission housing x Transmission case 14 mm (0.55 in.) 34 345 25
\
 \
17 mm (0.67 in.) 57 580 42
\
 \
Extension housing x Transmission case 34 345 25
\
 \
Valve body x Transmission case 10 100 7
\
 \
Oil strainer 10 100 7
\
 \
Oil pan 7.4 75 65 in.
Vlbf\
 \
No.1 vehicle speed sensor 16 160 12\
 
\

\
No.2 vehicle speed sensor 

5.4 

55 

48 in.
Vlbf
\
 \
Solenoid wiring stopper plate 5.4 55 48 in. Vlbf
\
 \
O/D direct clutch speed sensor 5.4 55 48 in. Vlbf
\
 \
Transmission output flange 123 1,250 90
\
 \
Throttle cable x Transmission case 5.4 55 48 in. Vlbf
\
 \
Union 29 300 22
\
 \
Cooler pipe union nut 34 350 25
\
 \
Drive plate x Crankshaft 99 1,000 72
\
 \
Torque converter clutch x Drive plate 33 340 25\
 \
Park/Neutral position switch Bolt 13 130 9\
 \
Nut 6.9 70 61 in. Vlbf\
 
\

\
Control shaft lever
 

16
 

160
 

12
±
A340E (1UZ±FE) AUTOMATIC TRANSMISSION SERVICE SPECIFICATIONSAT±123
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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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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
±
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)
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION SPEED SENSORAT±17
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HOW TO PROCEED WITH TROUBLESHOOTING
AT09N±0D
1. CUSTOMER PROBLEM ANALYSISUsing the customer problem analysis check sheet for reference, ask the c\
ustomer in as much detail as
possible about the problem.
2. CHECK AND CLEAR THE DIAGNOSTIC TROUBLE CODES (PRECHECK) Before confirming the problem symptom, first check if there are any diagnostic\
trouble malfunction codes
stored in memory. When there are malfunction codes, make a note of them, then clear them\
and proceed
to ª3. Problem Symptom Confirmationº.
3. PROBLEM SYMPTOM CONFIRMATION Confirm the problem symptoms.
4. SYMPTOM SIMULATION If the problem does not reappear, be sure to simulate the problem by mainly checking the circuits indica\
ted
by the diagnostic trouble code in step 2., using ªProblem Simulation me\
thodº.
5. DIAGNOSTIC TROUBLE CODE CHECK Check the diagnostic trouble codes. Check if there is abnormality in the\
sensors or the wire harness.
If a malfunction code is output, proceed to ª6. Diagnostic Trouble Code Chartº.
If the normal code is output, proceed to ª11. Matrix Chart of Problem Symptomsº.
Be sure to proceed to ª6. Diagnostic Trouble Code Chartº after the steps 2. and 3. are completed.
If troubleshooting is attempted only by following the malfunction code sto\
red in the memory is output, errors
could be made in the diagnosis.
6. DIAGNOSTIC TROUBLE CODE CHART If a malfunction code is confirmed in the diagnostic trouble code check, p\
roceed to the inspection proce-
dure indicated by the matrix chart for each diagnostic trouble code.
7. PRELIMINARY CHECK Carry out a preliminary check of the transmission oil level, throttle ca\
ble adjustment, etc.
8. SHIFT POSITION SIGNAL CHECK
Carry out the shift position signal check when the transmission gears do\
not up±shift, down±shift or lock±
up. This is to check the output condition from the ECM to each solenoid. If the r\
esults are NG, then it is
likely that the trouble is in the electrical system (particularly in th\
e sensors or the ECM).
Proceed to Part 1 (Electrical System) under ª11. Matrix Chart of Problem Symptomsº. If all the circuits speci-
fied in Part 1 are OK, check the ECM and replace it.
9. MECHANICAL SYSTEM TEST (Stall Test, Time Lag Test, Line Pressure Test, Accumulator Back Pressure Test)
If the malfunction is found in the stall test, time lag test, line press\
ure test or accumulator back pressure
test, check the parts indicated in the respective tests. If the problem is th\
at ªshift shock is largeº, perform
the accumulator back pressure test.
10. MANUAL SHIFTING TEST If the results of the manual driving test are NG, it is likely that the trouble is in the mechanical system or
hydraulic system. Proceed to Part 2 (Mechanical System) under the Matrix Chart \
of Problem Symptoms.
AT±32
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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11. MATRIX CHART OF PROBLEM SYMPTOMSIf the normal code is confirmed in the diagnostic trouble code check, perform inspection according to the
inspection order in the matrix chart of problem symptoms. Perform diagno\
sis of each circuit or part in the
order shown in the Matrix Chart. The Matrix Chart contains 3 chapters, Electronically Controlled Circuits
in Chapter 1, On±vehicle Inspection in Chapter 2 and Off±vehicle Inspection in Chapter 3. If all the circuits
indicated in Chapter 1 are normal, proceed to Chapter 2. If all the parts indicated i\
n Chapter 2 are normal,
proceed to Chapter 3. If all the circuits and parts in Chapter 1±Chapter 3 are normal and the trouble still
occurs, check and replace the ECM.
12. CIRCUIT INSPECTION Perform diagnosis of each circuit in accordance with the inspection order confirmed in 6. and 11. Judge
whether the cause of the problem is in the sensor, actuators, wire harness and connectors, or the ECM.
In some cases, the Flow Chart instructs that a throttle signal check, brak\
e signal check or kick down signal
check (in test mode) be performed. These are diagnosis functions used \
to check if signals are being input
correctly to the ECM.
13. PARTS INSPECTION Check the individual parts of the mechanical system and hydraulic system in t\
he order of the numbers indi-
cated in the Matrix Chart.
14. REPAIRS After the cause of the problem is located, perform repairs by following the i\
nspection and replacement pro-
cedures in this manual or '94 A340E and A341E Automatic Transmission Repair Manual (for LEXUS
SC400).
15. CONFIRMATION TEST
After completing repairs, confirm not only that the malfunction is eliminated\
, but also conduct a test drive,
etc., to make sure the entire electronically controlled transmission system i\
s operating correctly.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±33
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REMOVAL OF FRONT FENDER
(See page BO±92)
1. REMOVE FRONT BUMPER (See page BO±91)
2. REMOVE FRONT FENDER WHEEL OPENING MOULDING
(See page BO±102)
3. REMOVE FENDER LINER (a) Remove eight screws.
(b) Remove the liner with four clips.
4. REMOVE FRONT FENDER Remove eleven bolts and the fender.
CAUTION: Do not damage or shock the front airbag
sensor at all.
INSTALLATION OF FRONT FENDER
(See page BO±91)
1. INSTALL FRONT FENDER Install eleven bolts and the fender.
BO±92
±
BODY Front Fender
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SRS AIRBAG
(See page AB±2)
The LEXUS SC300 is equipped with an SRS (Supplemental Restraint System)\
airbag.
Failure to carry out service operations in the correct sequence could cause the airbag system to deploy,
possibly leading to a serious accident.
When removal or installation of airbag parts and the yellow wire harness\
and connector for the airbag is
necessary, refer to the precautionary notices in the AB section before performing\
the operation.

Work must be started after 20 seconds or longer from the time the ignition switch is set to the LOCK
position and the negative (±) terminal cable is disconnected from the batte\
ry.
(The airbag system is equipped with a back±up power source so that if wor\
k is started within 20 se-
conds of disconnecting the negative (±) terminal cable of the batte\
ry, the airbag may be deployed.

To avoid erasing the memory of each memory system, never use a back±up power supply from
outside the vehicle.

Before repairs, remove the airbag sensors if shocks are likely to be applied t\
o the sensors during
repaires.

The front airbag sensor set bolt has been anti±rust treated. When the\
sensor is removed, always
replace the set bolt with a new one.

If the front airbag sensors, center airbag sensor or steering wheel pad ha\
ve been dropped, or if there
are cracks, dents or other defects in the case, bracket or connector, replace them with new ones.

Never use airbag parts from another vehicle. When replacing parts, repla\
ce them with new parts.

Do not expose the front airbag sensors, center airbag sensor or steering w\
heel pad directly to hot air
or flames.

The airbag system's wire harness is integrated with the cowl wire harness assembly. The wires for the
airbag wire harness are encased in a yellow corrugated tube. All the connector\
s for the system are
also a standard yellow color. If the airbag system wire harness becomes disconnected or the
connector becomes broken due to an accident, etc., repair or replace it as shown \
on page AB±20.

The steering wheel must be fitted correctly to the steering column with the\
spiral cable at the neutral
position; otherwise, cable disconnection and other troubles may result. \
Refer to page AB±14 of this
manual concerning correct steering wheel installation.

When removing the steering wheel pad or handling a new steering wheel pad, i\
t should be placed with
the pad top surface facing up. In this case, the twin±lock type connector lock lever should be in the
locked state and care should be taken to place it so the connector will not be damaged. (\
Storing the
pad with its metallic surface up may lead to a serious accident if the a\
irbag inflates for some reason.)

Grease should not be applied to the steering wheel pad and the pad should not \
be cleaned with
detergents of any kind.

Store the steering wheel pad where the ambient temperature remains below 93 C (200 F), without
high humidity and away from electrical noise.

Information labels are attached to the periphery of the airbag component\
s. Follow the notices.

When the ignition switch is at ACC or ON and the airbag warning light remains on, the cent\
er airbag
sensor assembly has detected a malfunction code. (See page AB±30).
BO±8
±
BODY General Information
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