1991 LEXUS SC400 clutch

NGNG
OKNG
INSPECTION PROCEDURE
1Check resistance between terminals NCO+ and NCO± of ECM connector.
C
OK
PConnect the check harness A to the ECM (See EG sec-
tion).
Check resistance between terminals NCO
+ and NCO±
of ECM connector.
Resistance: 560 ± 680

Proceed to next circuit inspection shown on matrix chart
(See page AT±66). However, when diag. trouble code 67
is displayed, check and replace ECM.
2Check O/D direct clutch speed sensor.
C
OK
Hint
P
OK
C
Remove O/D direct clutch speed sensor from transmis-
sion (See page AT±17).
Measure resistance between terminals 1 and 2 of O/D
direct clutch speed sensor.
Resistance: 560 ± 680

Reference
Check the speed sensor function
Check voltage between terminals 1 and 2 of the speed
sensor when a magnet is put close to the front end of the
speed sensor then taken away quickly.
Voltage is generated intermittently.
The voltage generated is extremely low.
Replace O/D direct clutch speed sensor.
Check and repair harness and connector between
ECM and O/D direct clutch speed sensor (See
page IN±33).
AT±100±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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AT±66BE
IN±33
WIRING DIAGRAM
Stop Light Switch Circuit
CIRCUIT DESCRIPTION
The purpose of this circuit is to prevent the engine from stalling, while d\
riving in lockup condition, when
brakes are suddenly applied.When the brake pedal is operated, this switch sends a signal to ECM. Then
the ECM cancels operation of the lockup clutch while braking is in progress\
.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
AT±108±
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SERVICE SPECIFICATIONS
SERVICE DATA
AT0GH±02 Line pressure (wheel locked)\
 \

 \
 \
382±441 kPa 3.9±4.5 kgf/cm255±64 psi
 Engine idling D position\
 \

 \
 \
637±716 kPa 6.5±7.3 kgf/cm292±104 psi
 R position\
 \

\
1,265±1,402 kPa 12.9±14.3 kgf/cm2183±203 psi AT stall (Throttle valve opened) D position\
 \

 \
 \
1,726±2,060 kPa 17.6±21.0 kgf/cm2250±298 psi R position\
 \

 ECM SLN termina lNot ground\
 \
177±255 kpa 1.8±2.6 kgf/cm226±37 psi
 Ground\
 \
0
 Engine stall revolution\
 \
2,200+150 RPM
 Time lag N position " D position\
 \
Less than 1.2 seconds
 N position " R position\
 \
Less than 1.5 seconds
 Engine idle speed (Cooling fan and A/C OFF
)N position\
 \
650 RPM
 \
 \
Boot end face and inner cable stopper Throttle cable adjustment (Throttle valve fully closed)\
 \

 \
 \
0±1 mm 0±0.04 in.
 Torque converter clutch installing (Correct distance)\
 \
17.1mm 0.673 in.
 Drive plate runout Limit\
 \
0.20 mm 0.0079 in.
SHIFT POINT (Kick±down foot switch activated)
 Shift position Shifting point Vehicle speed km/h (mph)2
  Throttle valve fully opened 1"2 67±71 (42±44)
  2" 3 118±124 (73±77)
  3" O/D (NORM) 170±177 (106±110)
  3" O/D (PWR) 179±186 (111±116)
 D position (NORM or PWR) O/D "3 164±170 (102±106)
  3" 2 105±111 (65±69)  2" 1 53±57 (33±35) 

2 iti
 

Throttle valve fully opened 1
"2
 

67±71 (42±44)
 2 position
(NORM or PWR) 3
" 2 106±112 (66±70)
 
(NORM or PWR)
 2" 1 53±57 (33±35)
 L position Throttle valve fully opened 3 "2 104±109 (65±68)
 
L osition
(NORM or PWR) 2" 1 57±63 (35±39)
±
A340E (1UZ±FE) AUTOMATIC TRANSMISSION SERVICE SPECIFICATIONSAT±121
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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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DESCRIPTION
GENERAL DESCRIPTION
AT0GE±02
The A340E automatic transmission is a 4±speed Electronically Controlled \
Transmission with an intelligent
control like the A341E automatic transmission used in the LS400. The A34\
0E automatic transmission has
the following features.

When shifting, engine torque is controlled and the clutch hydraulic pressure\
in the transmission is
electronically controlled to reduce transmission shift shock.

A new type of ATF (ATF Type T±II) is used which provides improved shifting characteristics a\
nd
prevents deterioration in the ATF over time.
HINT: For the A340E automatic transmission, use ATF Type T±II or equivalent.

A super flow torque converter clutch is used to improve the transmission\
efficiency.
The A340E automatic transmission is mainly composed of a torque converter c\
lutch with lock±up clutch,
4±speed planetary gear unit, hydraulic control system and the electro\
nic control system.
To minimize the possibility of incorrect operation of the automatic transm\
ission, a shift lock mechanism has
also been added.
AT±2
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION DESCRIPTION
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Type of Transmission  A340E
\
 \
Type of Engine61UZ±FE
\
 
\

\
Torque Converter Clutch Stall Torque Ratio1.900 :1
\
 \
Torque Converter Clutch Lock±up MechanismEquipped
 Gear Ratio 1st Gear 2.804
  2nd Gear 1.531 


 

3rd Gear
 

1.000
  O/D Gear 0.705
  Reverse Gear 2.393
 
Number of Discs/Plates 
O/D Direct Clutch (C0) 
2 / 2 


 

Forward Clutch (C1)
 

6 / 6
  Direct Clutch (C2) 4 / 4
  2nd Brake (B0) 5 / 5 


 

1st & Reverse Brake (B2)
 

7 / 7
  O/D Brake (B0) 5 / 4
 2nd Coast Brake (B) Band Width mm (in.) 40 (1.57)
 ATF TypeATF Type T±II or equivalent 

Capacity liter (US qts, lmp. qts)
 

Total
 

8.2 (8.7, 7.2)
  Drain & Refill 1.9 (2.0, 1.7)
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION DESCRIPTIONAT±3
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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.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION OPERATIONAT±7
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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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