LEXUS SC400 1991 Service Repair Manual

4. REMOVE OIL COOLERRemove the three bolts and oil cooler.
INSPECTION OF OIL COOLER
INSPECT OIL COOLER
Check the oil cooler for damage or clogging.
If necessary, replace the oil cooler.
INSTALLATION OF OIL COOLER
(See Components on page CO±58)
1. INSTALL OIL COOLER Install the oil cooler with the three bolts.
Torque: 18 N Vm (180 kgf Vcm, 13 ft Vlbf)
2. CONNECT HOSES FROM OIL COOLER
Connect the following hoses:(1) Inlet hose (from reservoir tank)
(2) Outlet hose (from hydraulic motor)
3. INSTALL PS OIL COOLER Install the oil cooler with the two bolts.
4. REMOVE FENDER LINER
5. FILL COOLING FAN RESERVOIR TANK WITH FLUID
(See pages CO±23 and 24)
6. START ENGINE AND CHECK FOR LEAKS
±
COOLIING SYSTEM Electronically Controlled Hydraulic
Cooling Fan (Oil Cooler)CO±59
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Electronic Control Parts
(System Circuit)
(Cooling Fan ECU)
COMPONENTS FOR REMOVAL AND
INSTALLATION
CO±60±
COOLIING SYSTEM Electronically Controlled Hydraulic Cooling Fan
(Electronic Control Parts)
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INSPECTION OF COOLING FAN ECU
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 posi-
tion and the negative (±) terminal cable is disconnected from
the battery.
2. DISCONNECT COOLING FAN ECU CONNECTOR (See Components on page CO±60)
(a) Remove the instrument panel under cover.
(b) Remove the lower instrument panel finish panel and glove compartment door assembly.
(c) Disconnect the cooling fan ECU connector.
3. INSPECT COOLING FAN ECU (a) Connect the cable to the negative (±) terminal of thebattery.
(b) Check the connector on the wiring harness side as shown in the chart.
Check forTester connectionConditionSpecified value
Voltage1±GroundIgnition switch ONBattery voltage
Resistance2±3Solenoid valve at cold (20 5C (68 5F))7.5±8.5

Continuity4±Ground±Continuity
Continuity5±GroundThrottle valve openNo continuityContinuity5±GroundThrottle valve closedContinuity
Resistance9±10Coolant temp. at 80 5C (176 5F)1.48±1.58 k

(c) Disconnect the cable from the negative (±) terminal of
the battery.
4. RECONNECT COOLING FAN ECU CONNECTOR
5. RECONNECT CABLE TO NEGATIVE TERMINAL OF BATTERY
±
COOLIING SYSTEM Electronically Controlled Hydraulic
Cooling Fan (Electronic Control Parts)CO±61
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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)
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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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THREE±WAY CATALYST (TWC) SYSTEM
DESCRIPTION
To reduce HC, CO and NOx emissions, they are oxidized, reduced and convert\
ed to nitrogen (N2), carbon
dioxide (CO2) and water (H2O) by the catalyst.
OPERATION
EC±26±
EMISSION CONTROL SYSTEMS Three±Way Catalyst (TWC) System
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INSPECTION OF EXHAUST PIPE
ASSEMBLY
1. CHECK CONNECTIONS FOR LOOSENESS OR DAMAGE
2. CHECK CLAMPS FOR WEAKNESS, CRACKS OR
DAMAGE
INSPECTION OF CATALYTIC
CONVERTERS
CHECK FOR DENTS OR DAMAGE If any part of protector is damaged or dented to the extent that
it contacts the converter, repair or replace it.
INSPECTION OF HEAT INSULATORS
1. CHECK HEAT INSULATOR FOR DAMAGE
2. CHECK FOR ADEQUATE CLEARANCE BETWEEN
CATALYTIC CONVERTER AND HEAT INSULATOR
COMPONENTS FOR REPLACEMENT OF CATALYTIC CONVERTERS
±
EMISSION CONTROL SYSTEMS Three±Way Catalyst (TWC) SystemEC±27
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COMPONENTS FOR REPLACEMENT OF CATALYTIC CONVERTERS (Cont'd)
REPLACEMENT OF CATALYTIC
CONVERTERS
(Main Catalytic Converters)
1. REMOVE CATALYTIC CONVERTERS (MAIN)
(a) Check that the converter is cool.
(b) Remove the four bolts holding the pipe support bracket to thetransmission.
(c) Remove the four bolt and nuts holding the catalytic converters
to the front exhaust pipe. Remove the support bracket.
(d) Disconnect the front exhaust pipe from the catalytic converter,
and remove the two gaskets.
(e) Remove the three nuts, converter and gasket. remove the two
catalytic converters.
2. REINSTALL MAIN CATALYTIC CONVERTER
(a) Install a new gasket and the catalytic converter to the exhaust manifold with three new nuts. Install the two catalytic
converters.
Torque: 62 N Vm (630 kgf Vcm, 46 ft Vlbf)
(b) Install a new gasket to each front end of the front exhaust pipe,
and temporarily connect the front exhaust pipe to the catalytic
converters.
(c) Temporarily install the pipe support bracket to the transmission with the four bolts.
(d) Connect the front exhaust pipe to the catalytic converter with the four bolts and new nuts.
Torque: 43 N Vm (440 kgf Vcm, 32 ft Vlbf)
(e) Tighten the four bolts holding the pipe support bracket to the transmission.
Torque: 43 N Vm (440 kgf Vcm, 32 ft Vlbf)
EC±28±
EMISSION CONTROL SYSTEMS Three±Way Catalyst (TWC) System
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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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