1991 LEXUS SC400 transmission

±Memo±
AT00X±01
AT±30±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION SHIFT LOCK SYSTEM
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TROUBLESHOOTING
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTINGAT±31
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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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P. AT±35P. AT±37 ~ AT±38
P. AT±47
P. AT±60 P. AT±39
P. AT±50
P. AT±59
P. AT±65
P. AT±66 P. AT±68
P. AT±70
P. AT±78 ± AT±120
P. AT±37 ~ AT±38
P. IN±26
P. AT±41
AT±34
±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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PRECHECK TYPE I
In cases where the wireless door lock control system fails to operate only\
at a specific locality, perform this check
at that locality.
Open the driver's door
(Other doors remain closed).Using the door lock control switch, perform
ªlock, unlockº
*1 operation 10 times within 30
seconds.
How many times in 10 seconds is ªlock, un-
lockº
*1 operation performed automatically by
the ECU?
Noise is being produced at that locality.
*3
Vehicle is now receiving signals from a
transmitter of another vehicle (during
transmission from transmitter of another
vehicle).
Malfunction on vehicle side
(Proceed to Matrix Chart of Problem
Symptom on page
BE±454).
Does not
operate
2 times
3 times
Normal
*2
*1: Performing lock and unlock once counts as one time.
*2: If noise is not constantly produced at the locality being used and inspect\
ion is performed on an occasion when there is no noise, then it may happen that the system is judged normal.\
*3: If the conclusion is that noise is produced in the locality the vehicle is\
used, then transmitter use is limited in that locality. Limitations on usage are described below.
HINT:
Because the transmitter uses weak electromagnetic waves, it is easily affected by noise, so remote control with-
in the normal range becomes difficult.
To reduce the influence of noise, bring the transmitter as close as possib\
le to the back window glass (antenna
section), or touch (ground) the grooved key tip of the transmitter to\
the door key cylinder and then operate the
transmitter switch; this should make door lock remote control operation possible.
If door lock remote control operation is still not possible, insert the \
key in the door key cylinder and press the
transmitter switch.
±
BODY ELECTRICAL SYSTEM Wireless Door Lock Control SystemBE±445
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Description
The power source supplies power to each of the vehicle's electrical devices. It is composed of the battery, fuses
and relays, which are located centrally at relay block No. 2 and relay block No. 6 i\
n the engine compartment
and junction block No. 1 relay block No. 4 and relay block No. 5 in the \
cabin near the driver's feet.
Related systems for each Fuse
No.Part NameRelated Systems or Parts
1IGN
Charging System
AIR±BAG System1IGN
Engine
2ST
Starter
3WIPER
Wiper and Washer System
4HTR
Defogger System
A/C System
5ENGINE
Charging System
6RADIO NO. 2
Audio System
Power Mirror System

Cigarette Lighter
A/C System
7CIG
Combination Meter System
AIR±BAG System7CIG
Shift Lock System
Theft Deterrent System

TEL System
8STOP
Stop Light System
Cruise Control System
9TURN
Turn Signal and Hazard
Warning Light System
Cornnering Light System
10MIR HTR
Mirror Heater System
11PANEL
Illumination Light System
12ECU±B
Combination Meter System
AIR±BAG System

Combination Meter System
ECT System
13GAUGE
Back±Up Light
Transmission Indicator

Light Failare Sensor
ABS and TRAC

Power Seat System
Door Lock Control System

TEL System
Shift Lock System
14ECU±IG
Radiator Fan
Auto Antenna

Electric Tension Reducer System
Power Steering

Auto±Tilt away Steering
Cruise Control System
15TAIL
Taillight System
Side Marker15TAIL
Clearance Light
16DOOR
Power Seat System
Luggage Door Opener16DOOR
Door Lock Control System
Fuel Lid Opener System
17IG SWUpstream of ECU±IG, ENGINE, WIP, HTR, TURN, GAUGE, and ST Fuse
18PWR
Power Window System
Sliding Roof System
19ABS NO. 1
ABS and TRAC
20AM1Upstream of MIR HTR, TAIL, PANEL, STOP, ECUA±B, DOOR and PWR Fuse
21ALTUpstream of DEF, HTR, AM1, and ABS No. 1 Fuse
BE±18±
BODY ELECTRICAL SYSTEM Power Source
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DESCRIPTION
The combination meter has various meters and gauges which show the vehicle'\
s condition, warning lights which
monitor abnormalities in the vehicle and inform the driver, indicator lights which inform the driver of the condition
of each part of vehicle, and a function for illumination and brightness ad\
justment of meters and gauges.
The component parts of this system and their functions are described in \
the following table.
Parts NameFunction
SpeedometerThe speedometer needle moves in accordance with signals from the speed s\
ensor to
indicate the vehicle's speed.
TachometerThe tachometer needle moves in accordance with signals from the igniter \
to indicate the
engine's speed.
Water Temperatrue
GaugeThe water temperature gauge's needle moves in accordance with signals from the send-
er gauge and indicates the temperature of the engine coolant.
Fuel GaugeThe fuel gauge needle moves in accordance with signals from the sender g\
auge, indicat-
ing the amount of fuel remaining in the fuel tank.
OdometerThe odometer counts the total distance traveled by the vehicle in accord\
ance with pulse
signals from the speed sensor.
Twin Trip Switch
The twin trip meter counts the distance traveled by the vehicle in accor\
dance with pulse
signals from the speed sensor. It can be reset using a switch and can be used to switch
between trip meters A and B.
Circuit Plate
This plate contains the circuitry for each meter and gauge and for each \
warning light and
indicator light, as well as an internal engine oil level warning drive c\
ircuit, drive circuits for
the odometer and trip meter and brightness adjustment circuitry for each\
indicator.
Speed SensorMounted in the transmission, this sensor outputs pulse signals to the co\
mbination meter
in accordance with the speed of the output shaft.
Twin Trip SwitchOperation of this switch switches between the A and B trip meters and se\
nds reset sig-
nals to the combination meter.
Water
Temperature Sender
GaugeThis sender converts engine coolant temperatures to a resistance value i\
n signal form to
the combination meter.
Fuel Sender GaugeThis sender converts the level of fuel remaining in fuel tank to resista\
nce value and
sends the resistance value in signal form to combination meter.
Rheostat Light
Control VolumeIn order to adjust the degree of illumination of the combination meter, the resistance val-
ue of the built±in variable resistor is sent to the combination meter\
and rheostat light
control.
Fuel Level Warning
SwitchWhen the level of fuel remaining falls below a predetermined level, cont\
inuity is estab-
lished with this switch, which is built into the fuel sender gauge, caus\
ing a warning light
to light up.
Low Oil Pressure
Warning SwitchThis switch is mounted on the engine block. Continuity is established in\
this switch when
the oil pressure is low, causing a warning light to light up.
Integration Relay (Seat
Belt Warning Relay)
This relay receives current from fuse GAUGE and DOME and is connected to\
each
buckle switch, door courtesy switch, key unlock warning switch and warni\
ng light. As
part of the seat belt warning system, it sounds a chime and lights a war\
ning light when
seat belts are unfastened. As part of the key unlock warning system, it \
sounds a chime
when the set conditions are fulfilled.
Light Failure SensorThis sensor senses when a bulb in rear combination light is burnt out an\
d lights up a
warning light.
BE±96±
BODY ELECTRICAL SYSTEM Combination Meter
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