1991 LEXUS SC400 cooling

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
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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
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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)
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COOLIING SYSTEM Electronically Controlled Hydraulic
Cooling Fan (Electronic Control Parts)CO±63
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EG21P±02
TIMING BELT REMOVAL
(See Components for Removal and Installation)
1. REMOVE BATTERY CAUTION: Work must be started after 90 seconds from
the time the ignition switch is turned to the ªLOCKº posi-
tion and the negative (±) terminal cable is disconnected
from the battery.
2. REMOVE ENGINE UNDER COVER
3. DRAIN ENGINE COOLANT
4. REMOVE DRIVE BELT
Loosen the drive belt tension by turning the drive belt tension-
er counterclockwise, and remove the drive belt.
HINT: The pulley bolt for the drive belt tensioner has a left±
hand thread.
5. REMOVE RADIATOR RESERVOIR TANK
(a) Disconnect the coolant level sensor connector.
(b) Disconnect the following hoses: (1) Reservoir hose from water inlet housing
(2) Reservoir hose from radiator
(c) Remove the 2 bolts and reservoir tank bracket.
(d) Remove the bolt holding the reservoir tank to the radiator.
(e) Disconnect the reservoir tank from the reservoir tank bracket,
and remove the reservoir tank.
6. REMOVE RADIATOR ASSEMBLY
(a) Disconnect the ECT sensor connector (for cooling fan).
(b) Disconnect the ECT sensor wire clamp from the radiator fan shroud.
EG±46
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(c) Disconnect the following hoses:(1) 2 oil cooler hoses (for cooling fan) from pipes
(2) 2 radiator hoses
(3) 2 oil cooler hoses (for transmission) from radiator
HINT: Plug the hose ends.
(4) Suction hose from hydraulic pump
(5) Pressure hose from hydraulic pump
(d) Remove the 2 bolts, screw and upper radiator support. Remove the 2 upper radiator supports.
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(e) Slightly lift the radiator, and disconnect the 2 oil cooler hoses(for cooling fan) from the hose clamp on the radiator fan
shroud.
(f) Remove the radiator assembly.
(g) Remove the 2 lower radiator supports from the radiator.
7. DISCONNECT AIR CONDITIONING (A/C) COMPRESSOR
FROM ENGINE
(a) Disconnect the A/C compressor connector.
(b) Remove the nut, and disconnect the ground cable from the
A/C compressor stay.
(c) Remove the bolt and A/C compressor stay.
(d) Remove the 2 bolts, and disconnect the A/C compressor from the engine.
HINT: Put aside the A/C compressor, and suspend it.
8. REMOVE INTAKE AIR CONNECTOR
(a) Disconnect the following hoses: (1) Air hose from IAC valve
(2) Air hose (from air control valve on PS pump) from intake
air connector
(b) Remove the bolt holding the intake air connector to the cylinder head cover.
(c) Loosen the 2 hose clamps.
(d) Disconnect the intake air connector from the throttle body
and air cleaner hose, and remove the intake air connector.
EG±48
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37. INSTALL AIR CONDITIONING (A/C) COMPRESSOR
(a) Install the A/C compressor, compressor stay and groundcable with the nut and 3 bolts.
Torque:
49 NVm (500 kgf Vcm, 36 ft Vlbf) for bolt
29 N Vm (300 kgf Vcm, 22 ft Vlbf) for nut
(b) Connect the A/C compressor connector.
38. INSTALL RADIATOR ASSEMBLY
(a) Install the 2 lower radiator supports to the radiator.
(b) Place the radiator assembly on the body bracket.
(c) Slightly lift the radiator, and connect the 2 oil cooler hoses (for
cooling fan) to the hose clamp on the radiator fan shroud.
(d) Install the upper radiator support with the 2 bolts and screw. Install the 2 upper radiator supports.
Torque: 12 N Vm (120 kgf Vcm, 9 ft Vlbf)
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(e) Connect the following hoses:(1) 2 oil cooler hoses (for cooling fan) to pipes
(2) 2 radiator hoses
(3) 2 oil cooler hoses (for transmission) to radiator
(4) Suction hose to hydraulic pump
(5) Pressure hose to hydraulic pump
(f) Connect the ECT sensor connector (for cooling fan).
(g) Install the ECT sensor wire clamp to the radiator fan shroud.
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