1991 LEXUS SC400 speedometer

PRECAUTIONS FOR VEHICLES
EQUIPPED WITH TRACTION
CONTROL (TRAC) SYSTEM
When using a rear wheel two±wheel drum tester such as a
speedometer tester or chassis dynamometer, etc., or jacking up
the rear wheels and driving the wheels, always push in the TRAC
cut (ºTRAC OFFº) switch and turn the TRAC system OFF.
CONFIRM TRAC SYSTEM IS OFF
1. Press the TRAC cut (ºTRAC OFFº) switch.
2. Check that the TRAC OFF indicator light comes on when the
TRAC system is turned off by the TRAC cut switch.
HINT: The TRAC indicator light should always operate right after
the engine is restarted.
3. Begin measurements.
4. Press the TRAC cut switch again to change the TRAC to operative and check that the TRAC OFF indicator light goes
off.
HINT: The TRAC indicator light blinks when the TRAC system is
operative.
±
INTRODUCTION Precautions for V
ehicles Equipped with Traction Cotnrol
(TRAC)SystemIN±13
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OKNG
OKNG
INSPECTION PROCEDURE
1Check operation of speedometer.
Drive the vehicle and check if the operation of the speedometer in the c\
ombination meter is normal.
The No. 1 vehicle speed sensor is operating normally if the speedometer dis\
play is normal.C
Hint
Check speedometer circuit. See combination meter
troubleshooting on BE section.
2Check voltage between terminal SPD of ECM connector and body ground.
C
OK
P3. Connect the check harness A to the ECM (See EG section.)
4. Shift the shift lever to N position.
5. Jack up one of the rear wheels.
6. Turn ignition switch ON.
Measure voltage between terminal SPD of ECM con-
nector and body ground when he rear wheel is turned
slowly.
Voltage is generated intermittently.
Check speedometer circuit. See combination meter
troubleshooting on BE section.
Proceed to next circuit inspection shown on ma-
trix chart (See page AT±66).
However, when diag. trouble code 42 is displayed,
check and replace ECM.
AT±80±
A304E (1UZ±FE) AUTOMATIC TRANSMISSION TROUBLESHOOTING
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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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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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(Odometer and Twin Trip Switch)
REMOVAL AND INSTALLATION OF
ODOMETER AND TWIN TRIP SWITCH
(See page BE±103)
INSPECTION OF ODOMETER AND TWIN
TRIP SWITCH
INSPECT ODOMETER AND TWIN TRIP SWITCH
(Continuity)
Inspect continuity between terminals.
If continuity is not as specified, replace the odometer and twin
trip switch.
(Speedometer)
INSPECTION OF SPEEDOMETER
INSPECT SPEEDOMETER (ON±VEHICLE)Using a speedometer tester, inspect the speedometer for al-
lowable indication error and check the operation of the odom-
eter.
HINT: Tire wear and tire over or under inflation will increase
the indication error.
If error is excessive, replace the speedometer.
±
BODY ELECTRICAL SYSTEM Combination MeterBE±109
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3. DISCONNECT ENGINE WIRE
(a) Disconnect the following connector:(1) O/D direct clutch speed sensor connector
(2) No.1 VSS connector for Speedometer
(3) No.2 VSS connector for ECM
(4) PNP switch connector
(5) Solenoid connector
(b) D i s c onnect the 5 wire clamps from the brackets on
transmission.
4. REMOVE TRANSMISSION (See page AT±23)
±
1UZ±FE ENGINE ENGINE MECHANICALEG±151
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ENGINE & TRANSMISSION ASSEMBLY
EG34U±01
(See Components for Engine & Transmission Separation and
Assembly)
1. INSTALL TRANSMISSION TO ENGINE
(See page AT±23)
2. CONNECT ENGINE WIRE
(a) Connect the following parts: (1) O/D direct clutch speed sensor connector
(2) No.1 VSS connector for speedometer
(3) No.2 VSS connector for ECM
(4) PNP switch connector
(5) Solenoid connector
(b) Install the 5 wire clamps to the brackets on the transmission.
EG±190
±
1UZ±FE ENGINE ENGINE MECHANICAL
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Diag. Code 42Vehicle Speed Sensor Signal Circuit
CIRCUIT DESCRIPTION
The No. 1 speed sensor outputs a 20±pulse signal for every revolution of the rotor shaft, which is r\
otated by
the transmission output shaft via the driven gear. This signal is converted in the combination meter to 4±pulse
signal by the pulse conversion circuit and then sent to the Engine & ECT ECU. \
The ECU determines the vehicle
speed based on the frequency of these pulse signals.
Code No.Diagnostic Code Detecting ConditionTrouble Area
42
All conditions below are detected continuously for 8
sec. or more.(a) Vehicle speed signal: 0 km/h (0 mph)
(b) Engine speed: 1,500 rpm or more
(c) Neutral start switch (NSW): OFF
No. 1 speed sensor.

Combination meter.

Open or short in No. 1 speed sensor circuit.

ECU
HINT: In test mode, diag. code 42 is output when vehicle speed is 5 km/h (3\
mph) or below.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
Check operation of speedometer.
Check voltage of terminal SPD.
Check and replace ECU. Check speedometer circuit.
(See page
BE±131).
Check speedometer circuit.
(See page BE±131).
WIRING DIAGRAM
TR±98±
ENGINE TROUBLESHOOTING Circuit Inspection
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