sensor LEXUS SC300 1991 Service Repair Manual

OKNG
3Check sensor rotor and sensor installation.
C
OK
P
C
OK
C
OK
P
C
OK
Remove front speed sensor rotor (See page BR±71).
Check sensor rotor serrations.
No scratches or missing teeth.
Check the front speed sensor installation.
The installation bolt is tightened properly.
Remove the drive shaft (See page SA±64).
Check the sensor rotor serrations.
No scratches or missing teeth.
Check the rear speed sensor installation.
The installation bolt is tightened properly and there
is no clearance between the sensor and rear axle
carrier.
Replace speed sensor or rotor.
Check and replace ABS (& TRAC) ECU.
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±121
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DTC56, 57Pressure Sensor Circuit
CIRCUIT DESCRIPTION
The pressure sensor detects the TRAC accumulator hydraulic pressure and if \
it is low, it sends signals to the
ECU to operate the pump. If the pressure is high, it sends signals to th\
e ECU to stop the pump.
DTC No.DTC Detecting ConditionTrouble Area
56Pressure sensor terminal PR outputs below 1 V for
about 1 sec. or more.
Open or short in pressure sensor circuit.
57
TRAC (BRAKE) control is executed continuouslymore
than 255 times while pressure sensor ONsignal is not
output.

Pressure sensor
Fail safe function: If trouble occurs in the pressure sensor circuit, the ECU cuts off current to the TRAC
solenoid relay and prohibits TRAC control.
BR±134
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
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IN±33 ).
WIRING DIAGRAM
Ts Terminal Circuit
CIRCUIT DESCRIPTION
The sensor check circuit detects abnormalities in the speed sensor signal w\
hich can not be detected with
the diagnostic trouble code check.Connecting terminals Ts and E1 of the DLC1 in the engine compartment
starts the check.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
BR±150±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
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BO6847
NOTICE: True up the mounting section ofthe front airbag sensor very carefully and
accurately so that the sensor can bemounted at the correct angle.
Imaginary
Standard
Line
mm (in.)
(Two-Dimensional Distance)
Hote dia.
10 (0.39) nut
10 (0.33) nut
18 (0.71)
14 (0.55) nut 9 (0.35)
Name
Engine rear mounting member installation nut-front Propeller shaft center support bearing installation nut
Front floor reinforcement standard hole
Rear suspension member installation nut Rear spring support hole-front
Symbol
J, j
K, k
L, l
N, n
O, o
Hole dia.
9 (0.35)
9 (0.35)
8 (0.31) nut
13 y11 (0.51 y0.43)14 (0.55) nut
Name
Front crossmember working hole
Airbag front sensor installation hole
Airbag front sensor installation nut Front spring support hole = outer
Front suspension crossmember installation nut
Symbol
B, b
C, c
E, e
G, g H, h
UNDER BODY (Cont'd)
BODY DIMENSIONSDI-7
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Steering Wheel Pad (Airbag and Inflator)
Junction Block No. 1 Center Airbag
Front Airbag Sensor
Front Airbag Sensor
Warning Light Spiral Cable (in Combination Switch)
HANDLING PRECAUTIONS ON RELATED COMPONENTS
1. SRS AIRBAG
Locations of Airbag Components
This vehicle has an SRS AIRBAG (referred to as the airbag in the remain\
der of this manual).
When handling airbag components (removal, installation or inspection, e\
tc.), always follow the directions
given in the repair manual for the relevant model year to prevent the oc\
currence of accidents and airbag
malfunction.
Also take the following precautions when repairing the body:

Work must be started after 20 seconds or longer from the time the ignitio\
n switch is set to the LOCK
position and the negative (-) terminal cable is disconnected from the \
battery.
(The airbag system is equipped with a back-up power source so that if w\
ork is started within 20 seconds
of disconnecting the negative (-) terminal cable of the battery, the airbag may be deployed.)
When the negative (-) terminal cable is disconnected from the battery, memory of the clock and audio
systems will be cancelled. So before starting work, make a record of the\
contents memorized by each
memory system. Then when work is finished, reset the clock and audio sys\
tems as before.
When the vehicle has tilt and telescopic steering, power seat, and outsi\
de rear view mirror, which are all
equipped with memory function, it is not possible to make a record of th\
e memory contents.
So when the operation is finished, it will be necessary to explain this \
fact to the customer, and request
the customer to adjust the features and reset the memory.
To avoid erasing the memory of each memory system, never use back-up powe\
r supply from outside
the vehicle.

When using electric welding, first disconnect the airbag connector (yel\
low color and 2 pins) under the
steering column near the combination switch connector before starting wo\
rk.
Sensor Assembly
INTRODUCTIONIN-6
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Front
Fender Area
Area from the Front Fender Apron
to the Cowl Side Member


Before repairing the body, remove the airbag sensors if, during repair, shocks are likely to, be applied
to the sensors due to vibrations of the body or direct tapping with tool\
s or other parts.

Do not expose the airbag sensors or the steering wheel pad directly to h\
ot air or flames.
NOTICE:
1) The maximum ambient temperature tolerance is 120
°C (248°F) for the front airbag sensor, 105°C
(221
°F) for the center airbag sensor assembly and 93°C (200°F) for the steering wheel pad. If it is
possible that the ambient temperature may reach or exceed the temperatur\
e limit, remove the sen- sors and the steering wheel pad from the vehicle or protect them with a \
hot insulation material be-fore starting work.
2) Prior to welding, remove adjacent airbag sensors or the steering wheel p\
ad from the vehicle or protect them with fire-proof covers.

If the front fender or periphery of the vehicle is damaged, visually ins\
pect for damage to the front air-
bag sensor using the inspection procedures described in section AB of th\
e repair manual for the rele-
vant model year.
Also check that the dimensions of the body where the front airbag sensor\
is installed match those in
the body dimension drawings.
(The airbag may malfunction; or may not work, if the mounting angle or \
dimensions of the sensor
mount are not correct.)

If the vehicle is damaged, visually inspect for damage to the steering w\
heel pad using the inspection
procedures described in section AB of the repair manual for the relevant\
model year.

When removing the steering wheel pad or handling a new steering wheel pa\
d, keep the pad upper
surface facing upward. Also, lock the lock lever of the twin lock type c\
onnector at the rear of the pad
and take care not to damage the connector.
(Storing the pad with its metallic surface up may lead to a serious acc\
ident if the airbag inflates for
some reason.)

Store the steering wheel pad where the ambient temperature remains below\
93 °C (200 °F), without
high humidity and away from electrical noise.

Be careful not to let painting materials contact the airbag sensors.

Information labels are attached to the periphery of the airbag component\
s. Follow the NOTICES.
INTRODUCTIONIN-7
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SERVICE SPECIFICATIONS
SERVICE DATA
ThermostatValve opening temperature80±845C176±183 5F
Valve liftat 95 5C (203 5F) 10 mm0.39 in.
Radiator capRelief valve opening pressureSTD74±103 kPa
(0.75±1.05 kgf/cm, 10.7±14.9 psi)
Limit 59 kPa 0.6 kgf/cm 8.5 psi
On±vehicle
itifh
Oil pressure1,177±2,452 kPa
inspection for hy-
draulic cooling(12±25 kgf/cm, 171±356 psi)draulic cooling
fan
fan
Hydraulic pumpSpool valve45.8 mm1.803 in.
Rotor side clearanceSTD Drive rotor 0.02 mm0.0008 in.
Driven rotor 0.03 mm0.0012 in.
Limit Drive rotor 0.03 mm0.0012 in.
Driven rotor 0.04 mm0.0016 in.
Rotor body clearanceSTD 0.05±0.09 mm0.0020±0.0035 in.
Limit 0.10 mm0.0039 in.
Rotor tip clearanceSTD 0.02 mm0.0008 in.
Limit 0.03 mm0.0012 in.
Drive shaft bushing inside diameter17.00±17.05 mm0.6693±0.6713 in.
Drive shaft diameter16.97±16.98 mm0.6681±0.6685 in.
Drive shaft oil clearanceSTD 0.02±0.08 mm0.0008±0.0031 in.
Limit 0.08 mm0.0031 in.
Drive shaft preload (rotating torque)0.3 N Vm 3.0 kgf Vcm 2.6 in. Vlbf
Solenoid valve resistanceat cold 7.5±8.5

Hydraulic motorRotor side clearanceSTD0.01±0.04 mm0.0004±0.0016 in.
Limit 0.05 mm0.0020 mm
Drive shaft hole inside diameter14.000±14.011 mm0.5512±0.5516 in.
Drive shaft diameter13.973±13.984 mm0.5501±0.5506 in.
Drive shaft oil clearanceSTD 0.016±0.038 mm0.0006±0.0015 in.
Limit 0.04 mm0.0031 in.
Drive shaft preload (rotating torque)0.3 NVm 3.0 kgf Vcm 2.6 in. Vlbf
Water temp. Resistanceat 80 5C (176 5F)1.48±1.58 k

sensor
CO±64±
COOLIING SYSTEM Service Specifications
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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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REMOVAL OF RADIATOR
(See Components on page CO±15)
1. REMOVE BATTERY CAUTION: Work must be started after approx. 20 seconds or
longer from the time the ignition switch is turned to the
ºLOCKº position and the negative (±) terminal cable is dis-
connected from the battery.
2. REMOVE ENGINE UNDER COVERS
3. DRAIN ENGINE COOLANT (See page CO±6)
4. 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 two bolts and reservoir tank bracket.
(d) Disconnect the reservoir tank from the reservoir tank bracket, and remove the reservoir tank.
5. DISCONNECT HOSES Disconnect the following hoses:(1) Upper radiator hose from radiator
(2) Lower radiator hose from radiator
(3) Two oil cooler hoses (for A/T) from radiator. Plug hose end.
CO±16
±
COOLIING SYSTEM Radiator
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(4) Pressure hose from hydraulic motor
(5) Return hose from hydraulic motor
6. DISCONNECT COOLING FAN INLET PIPE FROM FAN SHROULD
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. DISCONNECT WATER TEMPERATURE SENSOR CONNECTOR
(a) Disconnect the water temperature sensor connector.
(b) Disconnect the wire cl amp from the radiator fan shrould.
9. REMOVE RADIATOR (a) Re mo ve th e two bo lts, scre w an d u pper radiator
support. Remove the two upper radiator supports.
±
COOLIING SYSTEM RadiatorCO±17
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