sensor LEXUS SC400 1991 Service Repair Manual

PREPARATION
SST (SPECIAL SERVICE TOOLS)
IllustrationPart No.Part NameNote
09268±41045Injection Measuring
Tool Set
(09268±41090)(No. 7 Union)
Injector
(09268±52010)(Injection Measuring
Attachment)
Injector
(09405±09015)(No. 1 Union)
Injector
09268±45012EFI Fuel Pressure
Gauge
09612±24014
Steering Gear
Housing Overhaul
Tool Set
(09617±24011(Steering Rack Wrench)
Fuel pressure pulsation damper
09631±22020
Power Steering
Hose Nut 14 x 17 mm
Wrench SetFuel line flare nut
09816±30010Oil Pressure
Switch Socket
Knock sensor
09842±30070Wire ªFº
EFI Inspection
Injector
09843±18020Diagnosis Check
Wire
09990±01000
Engine Control
Computer Check
Harness ªAº
±
EFI SYSTEM PreparationFI±9
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Preparation
SST (SPECIAL SERVICE TOOLS)
IllustrationPart No.Part NameNote
09268±41045Injection Measuring
Tool Set
(90268±41070)No. 4 Union
Injector
(09268±41080)No. 6 Union
Cold start Injector
(09268±52010)Injection Measuring
Attachment
Injector
09268±45012EFI Fuel Pressure
Gauge
09612±24014
Steering Gear
Housing Overhaul
Tool Set
(09617±24011)Steering Rack Wrench
Fuel pressure pulsation damper
09631±22020
Power Steering
Hose Nut 14 X 17 mm
Wrench SetFuel line flare nut
09816±30010Oil Pressure
Switch SocketKnock sensor
09842±30055Wire ªGº
EFI Inspection
Cold start Injector
09842±30070Wire ªFº
EFI Inspection
Injector
09843±18020Diagnosis Check
Wire
0990±01000
Engine Control
Computer
Check Harness ªAº
FI±10 ± PreparationEFI SYSTEM
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PRECAUTIONS
1. Before working on the fuel system, disconnect the cablefrom negative (±) terminal of the battery.
HINT: Any diagnostic code retained by the computer will be
erased when the battery terminal is removed. Therefore, if
necessary, read the diagnosis before removing the battery
terminal.
CAUTION: Turn the ignition switch to ºLOCKº. Discon-
nect the cable from the negative (±) terminal of the bat-
tery. Wait at least 20 seconds before proceeding with
work.
2. Do not smoke or work on open flame when working on the fuel system.
3. Keep gasoline away from rubber or leather parts.
INSPECTION PRECAUTIONS
MAINTENANCE PRECAUTIONS
1. CHECK CORRECT ENGINE TUNE±UP (See page EM±8)
2. PRECAUTIONS WHEN CONNECTING GAUGE (a) Use the battery as the power source for the timing light,tachometer, etc.
(b) Connect the test probe of a tachometer to the terminal IG
of the check connector.
3. IN EVENT OF ENGINE MISFIRE, FOLLOWING PRECAUTIONS SHOULD BE TAKEN
(a) Check proper connection of battery terminals, etc.
(b) Handle high±tension cords carefully.
(c) After repair work, check that the ignition coil terminalsand all other ignition system lines are reconnected
securely.
(d) When cleaning the engine compartment, be especially careful to protect the electrical system from water.
4. PRECAUTIONS WHEN HANDLING OXYGEN SENSOR (a) Do not allow oxygen sensor to drop or hit against anobject.
(b) Do not allow the sensor to come into contact with water.
±
EFI SYSTEM Precautions, Inspection PrecautionsFI±11
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PRECAUTIONS
1. Before working on the fuel system, disconnect the cablefrom negative (±) terminal of the battery.
HINT: Any diagnostic code retained by the computer will be
erased when the battery terminal is removed. Therefore, if
necessary, read the diagnosis before removing the battery
terminal.
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and negative (±) terminal
cable is disconnected from the battery.
2. Do not smoke or work on open flame when working on the fuel system.
3. Keep gasoline away from rubber or leather parts.
INSPECTION PRECAUTIONS
MAINTENANCE PRECAUTIONS
1. CHECK CORRECT ENGINE TUNE±UP (See page EM±8)
2. PRECAUTIONS WHEN CONNECTING GAUGE (a) Use the battery as the power source for the timing light,tachometer, etc.
(b) Connect the test probe of a tachometer to the terminal IG of the check connector.
3. IN EVENT OF ENGINE MISFIRE, FOLLOWING PRECAUTIONS SHOULD BE TAKEN
(a) Check proper connection of battery terminals, etc.
(b) Handle high±tension cords carefully.
(c) After repair work, check that the ignition coil terminalsand all other ignition system lines are reconnected
securely.
(d) When cleaning the engine compartment, be especially careful to protect the electrical system from water.
4. PRECAUTIONS WHEN HANDLING OXYGEN SENSOR (a) Do not allow oxygen sensor to drop or hit against anobject.
(b) Do not allow the sensor to come into contact with water.
FI±12
± Precautions, Inspection PrecautionsEFI SYSTEM
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11. REMOVE LH NO.3 TIMING BELT COVER(a) Remove the four mounting bolts.
(b) Disconnect the cord grommet from the timing belt cover,
and remove the timing belt cover.
(c) Remove the cord grommet from the high±tension cord.
12. REMOVE LOWER HIGH±TENSION CORD COVER (a) Disconnect the high±tension cord from the RH ignitioncoil.
(b) D i s c onnect the high±tension cords from the
high±tension cord cover.
(c) Remove the bolt and cord cover.
13. REMOVE THROTTLE BODY (a) Disconnect the following connectors:(1) Throttle position sensor connector
(2) (w/ TRAC) Sub±throttle position sensor connector
(3) (w/ TRAC) Sub±throttle actuator connector
(b) Disconnect the following hoses: (1) Heater water hose from heater water valve FI±29
EFI SYSTEM
± Fuel System (Cold Start Injector)
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(4) Heater water hose to heater water valve
(e) Connect the following connectors: (1) Throttle position sensor connector
(2) (w/ TRAC)
Sub±throttle position sensor connector
(3) (w/ TRAC) Sub±throttle actuator connector
5. INSTALL LOWER HIGH±TENSION CORD COVER (a) Connect the end portions of the high±tension cord to the
cord clamps
(b) Install the high±tension cord cover with the bolt.
(c) Install the clamps on the high±tension cords to the
high±tension cord cover.
(d) Connect the high±tension cord to the RH ignition coil.
7. INSTALL RH NO.3 TIMING BELT COVER (a) Install the three gaskets to the timing belt cover.
(b) Fit portion A of the timing belt cover, matching it with the
lower high±tension cord cover.
(c) Install the timing belt cover with the three bolts. FI±39
EFI SYSTEM
± Fuel System (Cold Start Injector)
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ENGINE SPEED SENSOR
COMPONENTS FOR REMOVAL AND
INSTALLATION
REMOVAL OF ENGINE SPEED SENSOR
1. DISCONNECT CABLE FROM NEGATIVE TERMINAL OFBATTERY
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and the negative (±) termi-
nal cable is disconnected from the battery.
2. REMOVE ENGINE UNDER COVER
3. DISCONNECT ENGINE SPEED SENSOR CONNECTOR
4. REMOVE ENGINE SPEED SENSOR Remove the bolt and engine speed sensor.
INSTALLATION OF ENGINE SPEED
SENSOR
1. INSTALL ENGINE SPEED SENSOR
Torque: 6.4 N Vm (65 kgf Vcm, 56 in. Vlbf)
2. CONNECT ENGINE SPEED SENSOR CONNECTOR
3. INSTALL ENGINE UNDER COVER
4. CONNECT CABLE TO NEGATIVE TERMINAL OF
BATTERY
IG±30
±
IGNITION SYSTEM Engine Speed sensor
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SERVICE SPECIFICATIONS
SERVICE DATA
Ignition timing8±125 BTDC @ idlegg
(w/ Terminals TE1 and E1 connected)
Firing order1±8±4±3±6±5±7±2
Spark plugTypeNDPK20R11g
NGK BKR6EP11
Electrode gapNew plug STD 1.1 mm 0.043 in.
Used plug Limit 1.3 mm 0.051 in.
High±tensionResistance25 k
per cordg
cord
Ignition coilPrimary coil resistance0.40±0.50
gy
Secondary coil resistance10.0±14.0 k

Cam positionResistanceat ±10± +40 5C (14±104 5F)835±1,350

sensor
Engine speedResistanceat ±10± +40 5C (14±104 5F)835±1,350

sensor
TORQUE SPECIFICATIONS
Part tightenedNVmkgf Vcmft Vlbf
Spark plug X Cylinder head1818013
Cam position sensor X Distributor housing18185 13
Distributor cap X Distributor housing3.839 34 in. Vlbf
Distributor rotor X Camshaft timing pulley3.839 34 in. Vlbf
RH No.2 timing belt cover X Cylinder block (for 12 mm head)16160 12
Drive belt idler pulley X Hydraulic pump37380 27
Engine speed sensor X Oil pump6.46556 in. Vlbf
IG±32±
IGNITION SYSTEM Service Specifications
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DESCRIPTION
The ECU is programmed with data for optimum ignition timing under any and a\
ll operating conditions. Using
data provided by sensors which monitor various engine functions (rpm, i\
ntake air volume, engine temperature,
etc.) the microcomputer (ECU) triggers the spark at precisely the right ins\
tant.
The ECU monitors the engine condition by signals from each sensor, calculates the ignition timing and sends
an ignition signal to the igniter. High voltage from the ignition is distributed to each spark plug in th\
e appropriate
order to generate a spark between the electrodes, which ignites the air±fu\
el mixture.
IGNITERS The igniter temporarily interrupts the primary current with the ignition si\
gnal (IGT signal) from the ECU and
generates sparks at the spark plug. Also, as a fail±safe measure, when ignitio\
n occurs, an ignition confirmation
signal (IGF signal) is sent to the ECU.
IGNITION COIL
The ignition coil uses a closed core coil with the primary coil wrapped \
around the core and the secondary
coil wrapped around the primary coil. This allows the generation of a hi\
gh voltage sufficient to cause a spark
to jump across the spark plug gap.
DISTRIBUTORS
This correctly distributes high voltage to the spark plug of each cylind\
er in the specified ignition order.
ENGINE SPEED SENSOR The engine speed sensor detects the crank angle.
CAM POSITION SENSORS The RH and LH cam position sensors detect the cam angle.
IG±2
±
IGNITION SYSTEM Description
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INSPECTION OF CAM POSITION
SENSORS
1. DISCONNECT CAM POSITION SENSOR CONNECTORS(a) (RH Cam Position Sensor)Disconnect the cam position sensor connector from the
ignition coil bracket.
(See steps 5 (a) on page IG±24)
(b) Disconnect the cam position sensor connectors.
2. INSPECT CAM POSITION SENSOR RESISTANCE Using an ohmmeter, measure the resistance between termi-
nals.
Resistance (Cold):
835±1,350
at ±10± +40 5C (14±104 5F)
If the resistance is not as specified, replace the cam position
sensor.
3. RECONNECT CAM POSITION SENSOR CONNECTORS
INSPECTION OF ENGINE SPEED
SENSOR
1. REMOVE ENGINE SPEED SENSOR (See page IG±30)
2. INSPECT ENGINE SPEED SENSOR RESISTANCE Using an ohmmeter, measure the resistance between termi-
nals.
Resistance (Cold):
835±1,350
at ±10± +40 5C (14±104 5F)
If the resistance is not as specified, replace the engine speed
sensor.
3. REINSTALL ENGINE SPEED SENSOR (See page IG±30)
INSPECTION OF ENGINE SPEED
SENSOR
(See procedure Spark Test on page IG±6)
IG±10
±
IGNITION SYSTEM On±Vehicle Inspection
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