belt LEXUS SC400 1991 Service Service Manual

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.
BE±96±
BODY ELECTRICAL SYSTEM Combination Meter
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ON±VEHICLE INSPECTION
1. INSPECT BATTERY SPECIFIC GRAVITY ANDELECTROLYTE LEVEL
(a) Check the specific gravity of each cell.
Standard specific gravity:
1.27±1.29 when fully charged at 20 5C (68 5F)
If gravity is less than specification, charge the battery.
(b) Check the electrolyte quantity of each cell.
If insufficient, refill with distilled (or purified) water.
HINT: Check the indicator as shown in the illustration.
2. CHECK BATTERY TERMINALS, FUSIBLE LINKS AND FUSES
(a) Check that the battery terminals are not loose orcorroded.
(b) Check the fusible links and fuses for continuity.
H±fuse: ALT 150A AM1 100A
AM2 30A
M±fuse: IG SW 40A
Fuse: IGN 7.5A ENGINE 7.5A
INJ 30A
3. INSPECT DRIVE BELTHINT: A belt tensioner is used, so checking the belt tension
is not necessary.
(a) Visually check the drive belt for excessive wear, frayedcords, etc.
If necessary, replace the drive belt.
HINT:
w Cracks on rib side of a drive belt are considered
acceptable. If the drive belt has chunks missing from the
ribs, it should be replaced.
w The drive belt tension can be released by turning the
belt tensioner counterclockwise. The pulley bolt for the
belt tensioner has a left±hand thread.
±
CHARGING SYSTEM On±Vehicle InspectionCH±5
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(b) Check the belt tensioner operation.w Check that the belt tensioner moves downward
when the drive belt is pressed down at the points
indicated in the illustration with approx. 98 N ( 10
kgf, 22.0 lbf) of force.
w Check the alignment of the belt tensioner pulley to
make sure the drive belt has not slipped off the
pulley.
If necessary, replace the belt tensioner.
w Check that the arrow mark on the belt tensioner falls
within area A of the scale.
If it is outside area A, replace the drive belt.
HINT:
w When a new belt is installed, it should lie within area B.
If not, the drive belt is not correct.
w After installing a belt, check that it fits properly in the
ribbed grooves.
w Check by hand to confirm that the belt has not slipped
out of the groove on the bottom of the pulley.
4. REMOVE ENGINE UNDER COVER
5. VISUALLY CHECK ALTERNATOR WIRING AND LISTEN FOR ABNORMAL NOISES
(a) Check that the wiring is in good condition.
(b) C h e c k t h a t t h e r e i s n o a bnormal noise from the
alternator while the engine is running.
6. INSPECT CHARGE WARNING LIGHT CIRCUIT (a) Warm up the engine and then turn it off.
(b) Turn off all accessories.
(c) Turn the ignition switch ON. Check that the charge
warning light is lit.
(d) Start the engine. Check that the light goes off.
If the light does not go off as specified, troubleshoot the
charge light circuit.
CH±6
±
CHARGING SYSTEM On±Vehicle Inspection
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ALTERNATOR
COMPONENTS FOR REMOVAL AND
INSTALLATION
REMOVAL OF ALTERNATOR
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. REMOVE DRIVE BELT
Loosen the belt tension by turning the drive belt tensioner
counterclockwise, and remove the drive belt.
HINT: The pulley bolt for the belt tensioner has a left±hand
thread.
±
CHARGING SYSTEM AlternatorCH±9
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INSTALLATION OF ALTERNATOR
(See Components on page CH±9)
1. INSTALL ALTERNATOR (a) Install the alternator and A/T oil cooler bracket with the
bolt and nut.
Torque: 37 N Vm (380 kgf Vcm, 27 ft Vlbf)
(b) Connect the alternator connector.
(c) Connect the alternator wire with the nut and cap.
2. INSTALL DRIVE BELT Install the drive belt by turning the drive belt tensioner coun-
terclockwise.
HINT: The pulley bolt for the belt tensioner has a left±hand
thread.
3. CONNECT CABLE TO NEGATIVE TERMINAL OF BATTERY
4. PERFORM ON±VEHICLE INSPECTION (See steps 6 to 8 on pages CH±6 to 8)
5. INSTALL ENGINE UNDER COVER
CH±20
±
CHARGING SYSTEM Alternator
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TORQUE SPECIFICATIONS
Part tightenedNVmkgf Vcmft Vlbf
Engine drain plug X Cylinder block1818013
Coolant filler plug X Water inlet housing44450 33
Water pump X Cylinder block18185 13
Water inlet housing X Water pump18185 13
Water inlet X Water inlet housing18185 13
Radiator fan shroud X Radiator4.950 43 in. Vlbf
Radiator X Body12120 9
Cooling fan reservoir tank X Radiator fan shroud4.950 43 in. Vlbf
Cooling fan inlet pipe X Radiator fan shroud4.950 43 in. Vlbf
Cooling fan pressure hose X Hydraulic motor64650 47
Radiator reservoir tank X Upper radiator support4.950 43 in. Vlbf
Radiator reservoir tank X Radiator reservoir tank support4.950 43 in. Vlbf
Hydraulic pump rear housing X End plug (for spool valve)19200 14
Hydraulic pump front housing X Rear housing21210 15
Hydraulic pump pulley X Drive shaft59600 43
Solenoid valve X Hydraulic pump rear housing39400 28
Hydraulic pump suction port union X Rear housing13135 10
 Hydraulic pump X Cylinder block 12 mm head 16 160 12
  14 mm head 20 310 22
\
 \
Cooling fan pressure hose X Hydraulic pump 64 650 47
\
 \
RH No.2 timing belt cover X Cylinder block 16 160 12
\
 \
Drive belt idler pulley X Hydraulic pump 37 380 27
\
 \
A/C compressor X Hydraulic pump 49 500 36
\
 \
A/C compressor X Cylinder block 49 500 36\
 \
A/C compressor stay X Oil filter bracket 29 300 22\
 \
Hydraulic motor cover X Motor housing 28 290 21\
 
\

\
Hydraulic motor X Radiator fan shroud
 

4.9
 

50
 

43 in.
Vlbf
\
 \
Cooling fan X Hydraulic motor 15 150 11
\
 \
Cooling fan oil cooler X Body 18 180 13
\
 \
Water temperature sensor X Radiator 7.4 75 65 in. Vlbf
±
COOLIING SYSTEM Service SpecificationsCO±65
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Coolant which is heated in the water jacket is pumped to the radiator, through which a cooling fan blows
air to cool the coolant as it passes through. Coolant which has been coo\
led is then sent back to the engine by
the water pump, where it cools the engine. The water jacket is a network of channels in the shell of the cylinder bloc\
k and cylinderhead through which
coolant passes. It is designed to provide adequate cooling through the cylinders and combus\
tion chambers
which become heated during engine operation.
RADIATOR The radiator performs the function of cooling the coolant which has pass\
ed through the waterjacket and
become hot, and it is mounted in the front of the vehicle. The radiator consis\
ts of an upper tank and lower tank,
and a core which connects the two tanks. The upper tank contains the inlet \
for coolant from the water jacket
and the filler inlet. It also has a hose attached through which excess cool\
ant or steam can flow. The lower tank
contains the outlet for coolant and drain plug. The core contains many t\
ubes through which coolant flows from
the upper tank to the lower tank as well as cooling fins which radiate heat\
away from the coolant in the tubes.
The air sucked through the radiator by the cooling fan, as well as the wind generated by the ve\
hicle's travel,
passes through the radiator, cooling the coolant. Models with automatic transmission include an aut\
omatic
transmission fluid cooler built into the lower tank of the radiator. A cooling fan is mounted behind radiator to assist
the flow of air through the radiator. When the coolant temperature is low, the fan operates slowly to help the warm
up, and when the coolant temperature becomes high, the fan speed is increas\
ed to provide the air flow required
for cooling.
RADIATOR CAP (on Reservoir Tank)
The radiator cap is a pressure type cap which seals the radiator, resulting in pressurization of the radiator
as the coolant expands. The pressurization prevents the coolant from boi\
ling even when the coolant tempera-
ture exceeds 100 5C (212 5F). A relief valve (pressurization valve) and a vacuum valve (negati\
ve pressure valve)
are built into the radiator cap. The relief valve opens and lets steam esca\
pe through the overflow pipe when
the pressure generated inside the cooling system exceeds the limit (coolant temperature: 110±120 5C
(230±248 5F) pressure; 29.4±98.1 kPa (0.3±1.0 kgf/cm2, 4.3±14.2 psi)). The vacuum v\
alve opens to alleviate
the vacuum which develops in the coolant system after the engine is stopped\
and the coolant temperature
drops.
RESERVOIR TANK The purpose of the reservoir tank is to catch coolant overflows created by \
volumetrix expansion when the
coolant temperature increases. The cap of the reservoir tank is a pressure type\
which prevents deterioration
of the LLC (Long Life Coolant) caused by contact with atmospheric air, increases vaporization performance and
reduces loss of the coolant volume.
WATER PUMP The water pump is mounted on the front of the cylinder block and driven by t\
he reverse side of the timing
belt.
THERMOSTAT The thermostat has a wax type by±pass valve and is mounted in the wat\
er inlet housing. The thermostat
begins to open at the temperature of 80 5C (180 5F). When the coolant temperature is low, the valve closes to
prevent coolant flow to the radiator, thus permitting the engine to warm up rapidly. When the by±pass valve
opens the by±pass circuit, the engine coolant continues to circulate \
inside the engine, quickly and uniformly
warming up to the appropriate temperature. When the coolant temperature is high\
, the valve opens and coolant
flows to the radiator where it is cooled. When the wax inside the thermostat \
is heated, it expands and thus
creates pressure which overpowers the force of the spring which keeps the valve\
closed. When the wax cools,
its contraction causes the force of the spring to take effect once more, closing the valve.
ELECTRONICALLY CONTROLLED HYDRAULIC COOLING FAN (See page CO±22)
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COOLIING SYSTEM DescriptionCO±3
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WATER PUMP
COMPONENTS FOR REMOVAL AND
INSTALLATION
REMOVAL OF WATER PUMP
1. REMOVE TIMING BELT(See steps 1 to 35 on pages EM±35 to 43)
2. REMOVE RH IGNITION COIL (a) Disconnect the ignition coil connector.
(b) Remove the two bolts and ignition coil.
3. REMOVE WATER INLET AND INLET HOUSING (a) Disconnect the water by±pass hose from the water inlethousing.
CO±8
±
COOLIING SYSTEM Water Pump
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(b) Apply seal packing to the sealing groove of the waterinlet housing as shown in the illustration.
Seal packing: Part No. 08826±00100 or equivalent
w Install a nozzle that has been cut to a 2±3 mm
(0.08±0.12 in.) opening.
HINT: Avoid applying an excessive amount to the surface. w Parts must be assembled within 5 minutes of
application. Otherwise the material must be
removed and reapplied.
w Immediately remove nozzle from the tube and
reinstall cap.
(c) Install a new O±ring to the water inlet housing.
(d) Apply soapy water to the O±ring.
(e) Push the water inlet housing end into water pump hole.
(f) Install the water inlet and inlet housing assembly with the two bolts. alternately tighten the bolts.
Torque: 18 N Vm (185 kgf Vcm, 13 ft Vlbf)
HINT: Use bolts 25 mm (0.98 in.) in length.
(g) Connect the water by±pass hose to the water inlet
housing.
3. INSTALL RH IGNITION COIL (a) Install the ignition coil with the two bolts.
(b) Connect the ignition coil connector.
4. INSTALL TIMING BELT (See steps 4 to 43 on pages EM±47 to 57)
±
COOLIING SYSTEM Water PumpCO±11
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ELECTRONICALLY CONTROLLED HYDRAULIC COOLING FAN
Description
In this way system, the cooling fan ECU controls the hydraulic pressure ac\
ting on the hydraulic motor, thus
controlling the speed of the cooling fan steplessly in response to the c\
ondition of the engine and air conditioner.
Operation
The hydraulic pump is driven by a drive belt (V±ribbed belt). The sole\
noid valve adjusts the volume of oil
sent from the hydraulic pump to the hydraulic motor which drives the fan dir\
ectly, thereby controlling the fan
speed. Oil which has passed through the hydraulic motor is cooled by the oil coole\
r before returning to the reservoir
tank. The solenoid valve is controlled by the computer in accordance with the E/G\
rpm, water temp. and A/C
signals. CO±22
±
COOLIING SYSTEM Electronically Controlled Hydraulic
Cooling Fan (Description, Operation)
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