1991 LEXUS SC400 sensor

6. DISCONNECT COOLING FAN INLET PIPE FROM FANSHROULD
Remove the two bolts, brackets and bushings, and discon-
nect the inlet pipe.
7. DISCONNECT COOLING FAN RESERVOIR TANK FROM FAN SHROULD
(a) Disconnect the suction hose from the clamp on the fanshrould.
(b) Remove the four bolts, and disconnect the reservoir tank.
8. REMOVE RADIATOR FAN SHROULD (a) Disconnect the wire clamp (for temperature sensor)from the radiator fan shrould.
(b) Remove the four bolts, and disconnect the fan shrould from the radiator.
(c) Slightly lift the fan shrould, and disconnect the two oil cooler hoses (for cooling fan) from the hose clamp on
the fan shrould.
(d) Remove the fan shrould.
±
COOLIING SYSTEM Electronically Controlled Hydraulic Cooling Fan
(Hydraulic Motor)CO±49
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7. INSTALL RADIATOR RESERVOIR TANK(a) Install the reservoir tank to the reservoir tank bracket.
(b) Install the reservoir tank bracket with two bolts.
Torque: 4.9 N Vm (50 kgf Vcm, 43 in. Vlbf)
(c) Connect the following hoses:
(1) Reservoir hose to water inlet housing
(2) Reservoir hose to radiator
(d) Connect the coolant level sensor connector.
8. INSTALL BATTERY
9. FILL ENGINE WITH COOLANT (See page CO±7)
10. FILL COOLING FAN RESERVOIR TANK WITH FLUID
(See pages CO±23 and 24)
11. START ENGINE AND CHECK FOR LEAKS
12. INSTALL ENGINE UNDER COVER
±
COOLIING SYSTEM Electronically Controlled Hydraulic Cooling Fan
(Hydraulic Motor)CO±57
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(Water Temperature Sensor)
COMPONENTS FOR REMOVAL AND
INSTALLATION
INSPECTION OF WATER TEMPERATURE
SENSOR
1. DISCONNECT CABLE FROM NEGATIVE TERMINAL OFBATTERY
CAUTION: Work must be started after 20 seconds or
longer from the time the ignition switch is turned to the
ºLOCKº position and the negative (±) terminal cable is
disconnected from the battery.
2. REMOVE ENGINE UNDER COVER
3. DRAIN ENGINE COOLANT (See page CO±6)
4. REMOVE WATER TEMPERATURE SENSOR (a) Disconnect the water temperature sensor connector.
(b) Remove the water temperature sensor from left side ofthe radiator lower tank.
(c) Remove the O±ring from the water temperature sensor.
CO±62
±
COOLIING SYSTEM Electronically Controlled Hydraulic
Cooling Fan (Electronic Control Parts)
WhereEverybodyKnowsYourName

5. INSPECT WATER TEMPERATURE SENSORUsing an ohmmeter, measure the resistance between the ter-
minals.
Resistance: 1.48±1.58 k
at 80 5C (176 5F)
If the resistance is not as specified, replace the sensor.
6. REINSTALL WATER TEMPERATURE SENSOR (a) Install a new O±ring to the water temperature sensor.
(b) Apply soapy water to the O±ring.
(c) Install the water temperature sensor to the radiator.
Torque: 7.4 N Vm (75 kgf Vcm, 65 in. Vlbf)
(d) Connect the water temperature sensor connector.
7. REFILL WITH ENGINE COOLANT (See page CO±7)
8. REINSTALL ENGINE UNDER COVER
9. RECONNECT CABLE FROM NEGATIVE TERMINAL OF BATTERY
(A/C High±Pressure Switch)
INSPECTION OF A/C HIGH±PRESSURE
SWITCH
1. DISCONNECT HIGH±PRESSURE SWITCH CONNECTOR
2. INSTALL MANIFOLD GAUGE SET (See AC section)
3. INSPECT HIGH±PRESSURE SWITCH(a) Wh e n th e A/C switch is OFF, ch e ck th a t th e re iscontinuity between terminals 2 and 3. (When the
pressure is 1,226 kPa (12.5 kgf/cm
2, 178 psi) or lower.)
(b) When the A/C switch and blower switch are ON, check
that there is no continuity between terminals 2 and 3.
(When the pressure is 1,520 kPa (15.5 kgf/cm
2, 220 psi)
or higher.)
If continuity is not as specified, replace the switch.
4. REMOVE MANIFOLD GAUGE SET
5. RECONNECT HIGH±PRESSURE SWITCH CONNECTOR
(Solenoid Valve)
(See page CO±36)
±
COOLIING SYSTEM Electronically Controlled Hydraulic
Cooling Fan (Electronic Control Parts)CO±63
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SERVICE SPECIFICATIONS
SPECIFICATIONS
VSV (For EVAP) Resistance30±34

VSV (For EGR)Resistance33±39

TORQUE SPECIFICATIONS
Part tightenedN mkgf cmftVlbf
VSV for EGR X Intake manifold18185 13
EGR valve X Intake manifold18185 13
EGR valve X EGR Pipe64650 47
Catalytic converter (Front) X Exhaust manifold62630 46
Catalytic converter (Front) X Front Exhaust pipe43440 32
Front exhaust pipe X Center exhaust pipe43440 32
Sub±oxygen sensor X Front exhaust pipe1818013
EC±20±
EMISSION CONTROL SYSTEMS Service Specifications
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(Sub±Catalytic Converter (USA Spec.
only)
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. DISCONNECT SUB±OXYGEN SENSOR CONNECTORS Disconnect the grommet from the floor, and disconnect the
sub±oxygen sensor from the front exhaust pipe.
3. REMOVE FRONT EXHAUST PIPE (SUB±CATALYTIC CONVERTER)
(a) Remove the four bolts holding the front exhaust pipe tothe transmission.
(b) Remove the two bolts and nuts holding the front exhaust
pipe to the center exhaust pipe.
(c) Remove the four bolts and nuts holding the front pipe to the catalytic converter, and remove the pipe support
bracket, front pipe and three gaskets.
4. REINSTALL FRONT EXHAUST PIPE (SUB±CATALYTIC CONVERTER)
(a) Temporarily install the pipe support bracket to thetransmission with the four bolts.
(b) Install three new gaskets, the front exhaust pipe and pipe support bracket with the six bolts and new nuts.
Torque: 43 N Vm (440 kgf Vcm, 32 ft Vlbf)
(c) Tighten the four bolts holding the pipe support bracket
to the transmission.
Torque: 43 N Vm (440 kgf Vcm, 32 ft Vlbf)
5. RECONNECT SUB±OXYGEN SENSOR CONNECTORS
(a) Install the two sub±oxygen sensors to the front exhaustpipe.
Torque: 44 N Vm (450 kgf Vcm, 33 ft Vlbf)
HINT:
w Before installing the s ub±oxygen sensor, twist the
sensor wire counterclockwise 3 \frb\1/2\fre turns.
w After installing the sub±oxygen sensor, check that the
sensor wire is not twisted. If it is twisted, remove the
sub±oxygen sensor and reinstall it.
(b) Install the two wire grommets to the floor.
6. RECONNECT CABLE TO NEGATIVE TERMINAL OF
BATTERY
±
EMISSION CONTROL SYSTEMS Three±Way Catalyst (TWC) SystemEC±29
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SERVICE SPECIFICATIONS
SERVICE DATA
VSVResistance30±34

for EVAP
VSVResistance33±39

for EGR
EGR valveResistance19.9±23.4

(CALIF. only)
TORQUE SPECIFICATIONS
Part tightenedNVmkgf Vcmft Vlbf
VSV for EGR X Air intake chamber (Exc. USA Spec.)1818513
EGR valve X Air intake chamber18185 13
Catalytic converter (Main) X Exhaust manifold62630 46
Catalytic converter (Main) X Front exhaust pipe43440 32
Front exhaust pipe support bracket X Transmission43440 32
Front exhaust pipe X Center exhaust pipe43440 32
Main oxygen sensor X Front exhaust pipe4445033
EC±30±
EMISSION CONTROL SYSTEMS Servuce Specifications
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INSPECTION OF EGR VALVE
1. REMOVE EGR VALVE(a) Disconnect the following hoses:(1) Vacuum hose from EGR vacuum modulator
(2) Pressure hose from EGR vacuum modulator(USA Spec.)
(b) Disconnect the EGR Gas Temp. Sensor connector
(c) Loosen the nut for EGR pipe.
(d) Remove the two nuts, EGR valve and gasket.
2. INSPECT EGR VALVE Check for sticking and heavy carbon deposits.
If a problem is found, replace the EGR valve assembly.
3. REINSTALL EGR VALVE (a) Place a new gasket on the intake manifold.
(b) Install the EGR valve with the two nuts.
Torque: 18 N Vm (185 kgf Vcm, 13 ft Vlbf)
(c) Torque the nut for EGR pipe.
Torque: 64 N Vm (650 kgf Vcm, 47 ft Vlbf)
±
EMISSION CONTROL SYSTEMS Exhaust Gas Recirculation (EGR) SystemEC±15
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