engine LEXUS SC400 1991 Service Manual PDF

(f) Fully apply the parking brake and chock the 4 wheels.
(g) Start the engine and check idling RPM.
(h) Keep your left foot pressed firmly on the brake pedal and shift into D p\
osition.
(i) Measure the accumulator back pressure.
(j) With the conditions the same as in (h), ground the other probe of the test\
lead which has one end insertedinto the terminal SLN of the ECM harness side connector, then measure the accumulator back pressure
again.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±57
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LOCATION OF CONNECTORS
AT0LA±02
Location of Connectors in Engine Compartment
AT±72±
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DTC46No. 4 Solenoid Valve Circuit (For Accumula-
tor Back Pressure Modulation)
CIRCUIT DESCRIPTION
The No. 4 solenoid valve controls the hydraulic pressure acting on the
brakes and clutches of the planetary gear units when gears are shifted and
performs smooth gear shifting.
The ECM determines optimum operating pressure according to the signals
from the throttle position sensor, vehicle speed sensor and O/D clutch
speed sensor and controls the volume of current flow to the solenoid valve.
The amount of electric current to the solenoid is controlled by the (*) \
duty
ratio of ECM out put signals, causing momentary change to the hydraulic
pressure acting on the clutches during gear shifting.
When the duty ratio is high, the hydraulic pressure acting on the clutch\
es
is low.
(*) Duty Ratio
The duty ration is the ration of the period of continuity in one cycle. For\
example, if A is the period of continuity
in one cycle, and B is the period of non±continuity, then
DTC No.DTC Detecting ConditionTrouble Area
46
All conditions below are detected for 1 sec. or more.
2trip detection logic*
(a) ECM outputs duty signal to No. 4 solenoid in 90%
or higher duty ratio.
(b) Current to No. 4 solenoid:330
100 Ma OR LESS
(O/D OFF indicator light doesn't blink)
 No. 4 solenoid valve.
 Harness or connector between No. 4 sole-
noid valve and ECM
 ECM
*: See page AT±62.
Reference Reference
 Waveform between terminals SLN± and E
1when engine is idling. 
Waveform between terminals SLN± and E1 during shift
change.
AT±82±
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This sensor detects the rotation speed of the O/D input shaft from the
rotation of the O/D direct clutch drum.
Its construction is the same as that of the No. 2 vehicle speed sensor
(See page AT±86).
By comparing the O/D direct clutch speed signal and the No. 2 vehicle
speed sensor signal, ECM detects the shift timing of the gears and ap-
propriately controls the engine torque and hydraulic pressure in re-
sponse to various conditions, thus performing smooth gear shift.
DTC67O/D Direct Clutch Speed Sensor Circuit
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
67
All conditions below are detected for 4 secs. or more
2 trip detection logic*
(a) Gear position: 1st, 2nd and 3rd
(b) T/M input shaft rpm: 100 rmp or more
(c) T/M output shaft rpm: less than 300 rpm
(d) PNP: OFF (other than P or N position)

O/D direct clutch speed sensor.

Harness or connector between O/D direct
clutch speed sensor and ECM.

ECM
*: See page AT±62.
Reference

Wave form between terminals NCO
+ and NCO± during engine idling.
AT±98
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OKNG
OKNG
OKNG
INSPECTION PROCEDURE
1Main throttle position signal check.
C
OK
Hint
PTurn ignition switch ON (Do not start the engine).
Check voltage at the terminal T
T of the DLC2 while grad-
ually depressing the accelerator pedal from the fully
closed position to the fully opened position.
Voltage changes from 0 V to 8 V by stages.
Do not depress the brake pedal during this test. The
voltage will stay at 0 V if depressed.
Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
2Check throttle position sensor.
See engine troubleshooting section in EG section.
Replace throttle position sensor.
3Check harness and connector between ECM and throttle position sensor (S\
ee page IN±33).
Repair or replace harness or connector.
Check and replace ECM.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±103
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OKNG
OKNG
OKNG
INSPECTION PROCEDURE
1Check voltage between terminal KD of ECM connector and body ground.
C
OK
P1. Connect the check harness A to the ECM (See EGsection).
2. Turn ignition switch ON (Do not start the engine.)
Measure voltage between terminal KD of ECM connec-
tor and body ground when accel. pedal is fully de-
pressed or not.
Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
2Check kick±down switch.
C
OK
1. Disconnect dick±down switch connector. (See page AT±18)
2. Measure resistance between terminals 1 and 2 of kick±down switch connector when kick±down
switch is ON and OFF
Replace kick±down switch.
3Check harness and connector between ECM and kick±down switch, kick±down\
switch and
body ground (See page IN±33).
Repair or replace harness or connector.
Check and replace ECM
±
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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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OKNG
OKNG
OKNG
INSPECTION PROCEDURE
1Check operation of stop light.
Check if the stop lights go on and off normally when the brake pedal is operated and released.C
Check and repair stop light circuit (See BE section).
2Check stop light signal.
C
OK
1. Connect voltmeter to the terminals TT and E1 of the
DLC2.
2. Turn ignition switch ON (Do not start the engine).
3. Fully depress the accelerator pedal until the volt- meter indicates 8 V and hold it.
4. Depress and release the brake pedal and check the
voltage.
Proceed to next circuit inspection shown on matrix chart
(See page AT±66).
3Check harness and connector between ECM and stop light switch (See page\
IN±33).
Repair or replace harness or connector.
Check and replace ECM.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±109
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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)
±
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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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