1991 LEXUS SC400 lock

(1) Turn ignition switch LOCK.
(2) Disconnect battery negative (±) terminal cable,and wait at least 20 seconds.
(3) Connect steering wheel pad (squib) connector.
(4) Connect negative (±) terminal cable to battery, and wait at least 2 seconds.
Check squib.
Measure voltage at D+ on spiral cable side of con-
nector between spiral cable and steering wheel
pad.
Repair or replace spiral cable.
Diagnostic code 12 is not output.
Replace steering wheel pad.
From the results of the above inspection, the malfunctioning part can now be\
considered normal.
To make sure of this, use the simulation method to check.
Repair or replace harness or connector between center airbag sensor assembly a\
nd spiral cable.
Check spiral cable.
(1) Turn ignition switch ACC or ON, and wait at least 20 seconds.
(2) Using SST, connect terminals Tc and E
1 of
TDCL.
SST 09843±18020
(3) Check diagnostic code.
Codes other than code 12 may be output at this
time, but this is not relevant.
Voltage: Below 1 V
(1) Turn ignition switch LOCK.
(2) Disconnect connector between center airbag sensor assembly and spiral cable.
(3) Turn ignition switch ON.
AB±52
SRS AIRBAG
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(1) Connect negative (±) terminal cable to battery.
(2) Clear malfunction code 41 stored in memory(See page AB±32).
Check center airbag sensor assembly.
Replace center airbag sensor assembly.
(1) Turn ignition switch LOCK, and wait at least 2
seconds.
(2) Turn ignition switch ACC or ON, and wait at least 20 seconds.
(3) Using SST, connect terminals Tc and E
1 of
TDCL.
SST 09843±18020
(4) Check diagnostic code.
Codes other than code 13 may be output at this
time, but this is not relevant to this check.
Diagnostic code 13 is not output.
(1) Turn ignition switch LOCK.
(2) Disconnect battery negative (±) terminal cable, and wait at least 2 seconds.
(3) Connect steering wheel pad (squib) connector.
(4) Connect negative (±) terminal cable to battery.
(5) Clear malfunction code 41 stored in memory
(See page AB±32).
Check squib.
Replace steering wheel pad.
Codes other than code 13 may be output at this
time, but this is not relevant to this check.
Diagnostic code 13 is not output.
(1) Turn ignition switch LOCK, and wait at least 2
seconds.
(2) Turn ignition switch ACC or ON, and wait at least 20 seconds.
(3) Using SST, connect terminals Tc and E
1 of
TDCL.
SST 09843±18020
(4) Check diagnostic code.
From the results of the above inspection, the malfunctioning part can now be\
considered normal.
To make sure of this, use the simulation method to check. AB±57
SRS AIRBAG
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CHECK TERMINAL TT OUTPUT
VOLTAGE
AT00R±01
When a voltmeter is connected to the DLC1, the following
items can be checked.
1. Throttle position sensor signal
2. Brake signal
3. Shift position signal
1. VOLTMETER CONNECTION Connect the positive (+) probe of the voltmeter to terminal T
T
and the negative (±) probe to terminal E1 of the DLC2.
HINT: If a voltmeter with small internal resistance is used, the
correct voltage will not be indicated, so use a voltmeter with
an internal resistance of at least 10 k
.
2. TURN IGNITION SWITCH TO ON (DO NOT START THE
ENGINE)
3. CHECK THROTTLE POSITION SENSOR SIGNAL Check if the voltage changes from approximately 0 V to
approximately 8 V when the accelerator pedal is gradually
depressed from the fully closed position.
4. CHECK BRAKE SIGNAL (LOCK±UP CUT SIGNAL)
(a) Open the throttle valve fully to apply approximately 8 V to terminal T
T.
(b) In this condition, check terminal T
T voltage when the brake
pedal is depressed and released.
TT terminal voltage:
0 V (When brake pedal is depressed)
8 V (When brake pedal is released)
5. START ENGINE
6. CHECK SHIFT POSITION SIGNAL (VEHICLE SPEED ABOVE 60 KM/H OR 37 MPH)
Check up±shifting together with terminal T
T voltage.
HINT: Check for light shocks from up±shifting and for
changes in the tachometer.
 Gear Position Terminal TT output voltage 1st GearBelow 0.5 V 

2nd Gear1.5 ~
2 6 V
 3rd Gear3.5 ~ 4.6 V
 3rd Lock±up4.5 ~ 5.9 V
 O/D5.5 ~ 6.9 V
 O/D Lock±up6.5 ~ 7.9 V
If terminal TT output voltage check cannot be performed, per-
form the check of terminal T
T circuit on page AT±120.
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±39
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PROBLEM SYMPTOM CONFIRMATION
AT09U±07
Taking into consideration the results of the customer problem analysis, try to\
reproduce the symptoms of
the trouble. If the problem is that the transmission does not up±shift, \
does not down±shift, or the shift point
is too high or too low, conduct the following road test referring to the automatic shift schedu\
le and simulate
the problem symptoms.
ROAD TEST
AT09V±05NOTICE: Perform the test at normal ATF operating temperature
50±80 5C (122±176 5F).
1. D POSITION TEST (NORM AND PWR PATTERN)
Shift into the D position and fully depress the accelerator ped-
al and check the following points:
(a) Check up±shift operation
1" 2, 2 "3 and 3 "O/D up±shift takes place, and shift point
should conform to those shown in the automatic shift sched-
ule (See page AT±45)
Conduct a test under both Normal and Power patterns.
HINT:
w O/D up±shift or lock±up will not occur when the engine
coolant temp. is below 60
C (140
F) and speed is under
60 km/h (37 mph), or if there is a 10 km/h (6 mph)
difference between the set cruise control speed.
w 3rd up±shift or lock±up will not occur when engine
coolant temp. is below 35
C (95
F) and speed is under
40 km/h (25 mph).
(b) Check for shift shock and slip. In the same manner, check the shock and slip at the 1 "2,
2 " 3 and 3 "O/D up±shifts.
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A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±41
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(c) Check for abnormal noise and vibration.Run at the D position lock±up or O/D gear and check for ab-
normal noise and vibration.
HINT: The check for the cause of abnormal noise and vibra-
tion must be performed very thoroughly care as it could also
be due to loss of balance in the propeller shaft, differential,
torque converter clutch, etc..
(d) Check kick±down operation While running in the D position, 2nd, 3rd and O/D gears,
check to see that the possible kick±down vehicle speed limits
for 2 "1, 3 "2 and O/D "3 kick±downs conform to those indi-
cated on the automatic shift schedule. (See page AT±45)
(e) Check abnormal shock and slip at kick±down.
(f) Check the lock±up mechanism. (1) Drive in D position, O/D gear, at a steady speed (lock±upON) of about 58 km/h (36 mph).
(2) Lightly depress the accelerator pedal and check that the engine RPM does not change abruptly.
If there is a big jump in engine RPM, there is no lock±up.
2. 2 POSITION TEST Shift into the 2 position and fully depress the accelerator ped-
al and check the following points:
(a) Check up±shift operation Check to see that the 1 "2 up±shift takes place and that the
shift point conforms to that shown on the automatic shift
schedule. (See page AT±45)
HINT:
w There is no O/D up±shift and lock±up in the 2 position.
(b) Check engine braking While running in the 2 position and 2nd gear, release the ac-
celerator pedal and check the engine braking effect.
AT±42
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5. P POSITION TESTStop the vehicle on a gradient (more than 5
) and after shift-
ing into the P position, release the parking brake. Then check
to see that the parking lock pawl holds the vehicle in place.
AT±44
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PWR Mode (Kick±down foot switch deactivated)
Shift positionShifting pointVehicle speed km/h (mph)  Throttle valve fully opened 1"2 67±71 (42±44)  2"3 118±124 (73±77)  3"O/D 179±186 (111±116) 
Dposition
 O/D"3 149±155 (93±96) D position 3"2 95±100 (59±62)  2"1 22±26 (14±16)  Throttle valve fully closed 3"O/D 32±35 (20±22)  O/D"3 23±26 (14±16)  Throttle valve fully opened 1"2 67±71 (42±44) 
2 position
 3"2 106±112 (66±70)  2"1 10±13 (6±8) 
Lposition
 Throttle valve fully opened 3"2 104±109 (65±68) L position 2"1 57±63 (35±39)
LOCK±UP POINT
NORM Mode
 D position km/h (mph) 
Lock±upON
 
Lock±upOFF Throttle valve opening 5% Lock±up ON Lock±up OFF
 *3rd Gear 83±88 (52±55) 77±82 (48±51)
 O/D Gear 56±60 (35±37) 53±57 (33±35)
*: O/D Switch OFF
PWR Mode
D position km/h (mph)Lock±upONLock±upOFF Throttle valve opening 5%Lock±up ONLock±up OFF
 *3rd Gear 83±88 (52±55) 77±82 (48±51)
 O/D Gear 56±60 (35±37) 53±57 (33±35)
*: O/D Switch OFF
HINT:
(1) There is no lock±up in the 2 and L positions.
(2) In the following cases, the lock±up will be released regardless\
of the lock±up pattern.

When the throttle valve is completely closed.

When the brake light switch is ON.
(3) Shift up to 3rd will not occur when the engine coolant temp. is below 3\
5 C (95 F) and the vehicle speed
is below 40 km/h (25 mph).
(4) Shift±up to O/D will not occur when the engine coolant temp. is\
below 60 C (140 F) and the vehicle
speed is below 63 km/h (39 mph).
(5) During cruise control operation, the shift pattern is fixed in NOR\
M. And when the vehicle speed drops to 10 km/h (6 mph) or more below the cruise control set vehicle speed, s\
hift down from O/D to 3rd
occurs.
(6) The kick±down foot switch turns ON when the accelerator pedal i\
s depressed further with the throttle valve already fully open.
AT±46
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MANUAL SHIFTING TEST
AT0QV±01
HINT: With this test, it can be determined whether the trouble
is within the electrical circuit or is a mechanical problem in the
transmission.
1. DISCONNECT SOLENOID WIRE
2. INSPECT MANUAL DRIVING OPERATION Check that the shift and gear positions correspond with the
table below.
 Shift Position Gear Position
 D PositionO/D 2 Position3rd L Position1st 

R PositionReverse
 P PositionPawl Lock
HINT: If the L, 2 and D position gear positions are difficult to
distinguish, perform the following road test.
w
While driving, shift through the L, 2 and D positions.
Check that the gear change corresponds to the shift
position.
If any abnormality is found in the above test, the problem is
in the transmission itself.
3. CONNECT SOLENOID WIRE
4. CANCEL OUT DIAGNOSTIC TROUBLE CODE (See page AT±39)
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±59
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