1991 LEXUS SC300 coolant level

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Water Valve VSV Circuit
CIRCUIT DESCRIPTION
If the target air mix damper position is on the hot side beyond a predeter\
mined level, the A/C control
assembly turns ON Tr inside the A/C control assembly.
This turns the water valve VSV ON so that engine coolant flows to the he\
ater core.
If the target air mix damper position is on the cool side beyond a prede\
termined level, the A/C control
assembly OFF Tr inside the A/C control assembly.
This turns OFF the VSV and stops circulation of engine coolant to the he\
ater core, thus increasing the
cooling performance.
DIAGNOSTIC CHART
Check voltage between terminal WV of A/C
control assembly connector and body
ground .
Check water valve VSV.
Check for open and short in harness
and connector between VSV and A/C
control assembly .
Check and replace A/C control assembly.
Replace water valve VSV.
Repair or replace harness or
connector.
Proceed to next circuit inspection
shown on matrix chart
(See page
AC-36).
WIRING DIAGRAM
AC±90±
AIR CONDITIONING SYSTEM Troubleshooting
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( Coolant Level Warning Switch)
REMOVAL AND INSTALLATION OF COOLANT
LEVEL WARNING SWITCH
1. REMOVE COOLANT LEVEL WARNING SWITCH(a) Disconnect the connector.
(b) Remove the boot.
(c) Using the notches in the head of switch, turn the switchcounterclockwise and remove it.
NOTICE: Do not remove when engine is hot.
2. INSTALL COOLANT LEVEL WARNING SWITCH For installation, follow the removal procedure in reverse.
INSPECTION OF COOLANT LEVEL WARNING
SWITCH
1. INSPECT COOLANT LEVEL WARNING SWITCH(Continuity)
(a) Remove the radiator cap and open the radiator drainclock.
NOTICE: Do not remove when engine is hot.
(b) Drain the coolant about 1 liter. (1.1 US qts, 0.9 lmp. qts)
(c) Check that there is continuity between terminals (float down).
(d) Close radiator drain cock and fill the cooling system with
coolant.
(e) Check that there is no continuity between terminals (float up).
If continuity is not as specified, replace the switch.
2. INSPECT COOLANT LEVEL WARNING LIGHT (a) Disconnect the connector from the coolant level warning
switch and ground terminal 1 on the wire harness side
connector.
(b) Start the engine, check that the warning light lights up.
If the warning light does not light up, inspect the bulb or wire
harness.
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BODY ELECTRICAL SYSTEM Combination MeterBE±117
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PREPARATION
SST (SPECIAL SERVICE TOOLS)
IllustrationPart No.Part NameNote
09213±31021
Crankshaft Pulley
Puller
For removing steering wheel
RECOMMENDED TOOLS
IllustrationPart No.Part NameNote
09082±00015TOYOTA
Electrical Tester
09041±0030Torx Driver
T30
For removing and installing steering wheel pad and
power window motor
09042±00010Torx Socket
T30For removing and installing steering wheel pad and
power window motor
EQUIPMENT
Part NameNote
Voltmeter
Ammeter
Ohmmeter
Test lead
ThermometerWater temperature sender gauge, Engine oil level, Warning switch, Seat heater
SyphonBrake fluid level warning switch
Oil bathEngine oil level warning switch
Bulb (1.4 W)Coolant level warning ECU
Bulb (3.4 W)Fuel sender, gauge, Seat belt warning relay
Bulb (21 W)Turn signal flasher relay
Dry cell batteryFuel sender gauge
Heat lightSeat heater
Hexagon wrench (6 mm)Power seat
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BODY ELECTRICAL SYSTEM Preparation
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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.
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Parts NameFunction
Coolant Level
Warning SwitchThis switch is installed in the radiator reservoir tank. It lights up a \
warning light when the
coolant level becomes low.
Engine Oil Level
Warning SwitchThis switch is mounted in the engine oil pan. It lights a warning light \
when the engine oil
level is low.
Brake Fluid Level
Warning SwitchThis switch is mounted in the brake master cylinder reservoir tank. It l\
ights up a warning
light when the brake fluid level is low.
Parking Brake SwitchThis switch is on the parking brake lever bracket. Continuity in this sw\
itch is established
when the lever is released, causing a warning light to light up.
Door Courtesy SwitchContinuity is established in this switch when a door is opened, causing \
a warning light to
light up.
Warning LightsWhen an abnormality is detected in the vehicle, current is sent to these\
lights, or they are
grounded, causing them to light up.
Indicator LightsCurrent is sent to these lights, or they are grounded, causing them to l\
ight up and indicate
the vehicle's condition to the driver.
Window Washer Level
Warning SwitchThis switch is mounted in the window washer tank. It lights a warning li\
ght when the
window washer level becomes low.
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BODY ELECTRICAL SYSTEM Cominbation MeterBE±97
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CHECK AND REPLACEMENT OF
ENGINE COOLANT
1. CHECK ENGINE COOLANT LEVEL AT RESERVOIR TANK
The coolant level should be between the ºLOWº and ºFULLº
lines at low temperature.
If low, check for leaks and add coolant up to the ºFULLº line.
2. CHECK ENGINE COOLANT QUALITY There should be no excessive deposits of rust or scales
around the radiator cap or radiator filler hole, and the coolant
should be free from oil.
If excessively dirty, replace the coolant
3. REPLACE ENGINE COOLANT (a) Remove the radiator cap.
CAUTION: To avoid the danger of being burned, do not
remove it while the engine and radiator are still hot, as
fluid and steam can be blown out under pressure.
(b) Drain the coolant from the radiator drain cock andengine drain plug.
(c) Close the drain cock and plug.
Torque (Engine drain plug):
29 NVm (300 kgf Vcm, 22 ft Vlbf)
(d) Fill the system with coolant.
w Use a good brand of ethylene±glycol base coolant,
mixed according to the manufacturer's direction.
w Using coolant which includes more than 50 %
ethylene±glycol (but not more than 70%) is
recommended.
NOTICE:
w Do not use alcohol type coolant.
w The coolant should be mixed with demineralized water or
distilled water.
Coolant capacity (w/ Heater): M/T 8.5 liters (9.0 US qts, 7.5 Imp. qts)
A/T 8.4 liters (8.9 US qts, 7.4 Imp. qts)
(e) Install the radiator cap.
(f) Start the engine and check for leaks.
(g) Recheck the coolant level and refill as necessary.
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COOLING SYSTEM Check and Replacement of Engine CoolantCO±5
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CHECK AND REPLACEMENT OF
ENGINE COOLANT
1. CHECK ENGINE COOLANT LEVEL AT RESERVE TANKThe coolant level should be above the ºCOLD LEVELº at nor-
mal temperature (20 5C (68 5F)).
If low, check for leaks and add coolant up to the ºCOLD LEV-
ELº.
2. CHECK ENGINE COOLANT QUALITY There should not be any excessive deposits of rust or scales
around the radiator cap or reservoir tank filler hole, and the
coolant should be free from oil.
If excessively dirty, clean the coolant passages and replace
the coolant.
3. REPLACE ENGINE COOLANT (a) Remove the radiator cap from the reservoir tank.
CAUTION: To avoid the danger of being burned, do not
remove the cap while the engine and radiator are still hot,
as fluid and steam can be blown out under pressure.
(b) Remove the filler plug from the water inlet housing.
(c) Loosen the three drain plugs on the radiator and
cylinder block, drain the coolant from the radiator and
engine.
(d) Clean the coolant passages.
(e) Close the three drain plugs.
Torque (Engine drain plug):
18 NVm (180 kgf Vcm, 13 ft Vlbf)
CO±6±
COOLIING SYSTEM Check and Replacement of Engine Coolant
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(f) Slowly add coolant to water inlet housing until it is full.w Use a good brand of ethylene±glycol base coolant,
mixed according to the manufacturer's directions.
w Using coolant which includes more than 50%
ethylene±glycol (but not more 70%) than is
recommended.
NOTICE:
w Do not use alcohol type coolant.
w The coolant should be mixed with demineralized water or
distilled water.
Capacity (w/ Heater): 10.8 liters (11.4 US qts, 9.5 lmp. qts)
(g) Reinstall a new gasket and filler plug to the water inlethousing.
Torque: 44 N Vm (450 kgf Vcm, 33 ft Vlbf)
(h) Slowly add coolant to reservoir tank until it is full.
(i) Reinstall the radiator cap.
(j) Bleed the cooling system.
w Start the engine, and open the heater water valve.
w Maintain the engine speed at 2,000 rpm, and warm
up the engine.
(k) Check for leaks.
(l) Recheck the coolant level and refill as necessary.
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COOLIING SYSTEM Check and Replacement of Engine CoolantCO±7
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