ESP LEXUS SC400 1991 Service User Guide

(TURN SIGNAL AND HAZARD WARNING
LIGHT SYSTEM)
Description ± TURN SIGNAL AND
HAZARD WARNING LIGHT SYSTEM
The component parts of this system and their function are as shown in the f\
ollowing table.
Parts NameFunction
Turn Signal SwitchSwitches current from the turn signal flasher to the left side or right \
side.
Hazard Warning
SwitchModifies the circuit to the flasher relay and turn signal switch in acco\
rdance with the
respective switch positions.
Turn Signal FlasherReceives current from the hazard warning switch and flashes the turn sig\
nal lights by
switching the current to the lights ON and OFF.
PARTS LOCATION ± TURN SIGNAL
±
BODY ELECTRICAL SYSTEM Lighting SystemBE±65
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TROUBLESHOOTING
How to proceed with troubleshooting
Perform troubleshooting in accordance with the procedure on the followin\
g page.

CUSTOMER PROBLEM ANALYSIS
Using the customer problem analysis check sheet for reference, ask the c\
ustomer in as much detail as
possible about the problem.
CHECK AND CLEAR THE DIAGNOSTIC TROUBLE CODES (PRECHECK)
If the TRAC indicator light lights up, and the TRAC control does not ope\
rate, the ECU stores diagnostic
trouble codes corresponding to the problem in memory.
Before confirming the trouble, first check the diagnostic trouble code for any\
malfunction codes stored in
memory. When there are malfunction codes, make a note of them, then clear them and proceed to ª 
Problem Symptom Confirmationº.
 PROBLEM SYMPTOM CONFIRMATION,  SYMPTOM SIMULATION
Confirm the problem symptoms. If the problem does not reoccur, simulate the problem by initially checking
the circuits indicated by the diagnostic trouble code in step , using ªProblem simulation methodº.
 DIAGNOSTIC TROUBLE CODE CHECK
Check the diagnostic trouble codes. If a malfunction code is output, proceed \
to ª  Diagnostic Trouble
Code Chartº.
If the normal code is output, proceed to ª  Problem Symptoms Chartº.
Be sure to proceed to ª  diagnostic Trouble Code Chartº after steps and  are completed.
If troubleshooting is attempted only by following the malfunction code sto\
red in the memory, errors could
be made in the diagnosis.
 DIAGNOSTIC TROUBLE CODE CHART
If a malfunction code is confirmed in the diagnostic trouble code check,\
proceed to the inspection proce-
dure indicated by the matrix chart for each diagnostic trouble code.
 PROBLEM SYMPTOMS CHART
If the normal code is confirmed in the diagnostic trouble code check, perf\
orm inspection in accordance with
the inspection order in the problem symptoms chart.
 CIRCUIT INSPECTION
Proceed with diagnosis of each circuit in accordance with the inspection\
order confirmed in  and .
Determine whether the cause of the problem is in the sensor, actuators, wire harness and connectors or
the ECU.
\b SENSOR CHECK
Use the ABS warning light to check if each of the signals from speed sensors is \
being input correctly to
the ECU. Instructions for this check are given in the circuit inspection\
.
[10] REPAIRS After the cause of the problem is located, perform repairs by following the i\
nspection and replacement pro-
cedures in this manual.
[11] CONFIRMATION TEST
After completing repairs, confirm not only that the malfunction is eliminated\
, but also conduct a test drive
to make sure the entire TRAC system is operating correctly. And also check the ABS is operating correctly.
BR±166
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
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GENERAL DESCRIPTION
BR03E±06
1. Care must be taken to replace each part properly as it could affect the \
performance of the brakesystem and result in a driving hazard. Replace the parts with parts of the same part number or
equivalent.
2. It is very important to keep parts and the area clean when repairing the\
brake system.
3. If the vehicle is equipped with a mobile communication system, refer to the precaution \
in the IN section.
DESCRIPTION
BR03F±03
The service brakes consist of a foot brake which changes rotational energy to therma\
l energy to stop the
vehicle while it is being driven and a parking brake to keep the vehicle from m\
oving while it is parked.
OPERATION
FOOT BRAKE
BR03G±06
When the brake pedal is depressed, a vacuum builds up in the booster whi\
ch amplifies the pedal force,
pressing on the piston in the master cylinder. The piston movement raises the hydraulic pressure in the
cylinder. This hydraulic pressure is then applied to each respective brake cylin\
der, and acts to press the
brake pads against the rotating discs. The resulting friction converts the ro\
tational energy to thermal ener-
gy, stopping the vehicle.
BR±2±
BRAKE SYSTEM OPERATION
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GENERAL DESCRIPTION
BR03E±06
1. Care must be taken to replace each part properly as it could affect the \
performance of the brakesystem and result in a driving hazard. Replace the parts with parts of the same part number or
equivalent.
2. It is very important to keep parts and the area clean when repairing the\
brake system.
3. If the vehicle is equipped with a mobile communication system, refer to the precaution \
in the IN section.
DESCRIPTION
BR03F±03
The service brakes consist of a foot brake which changes rotational energy to therma\
l energy to stop the
vehicle while it is being driven and a parking brake to keep the vehicle from m\
oving while it is parked.
OPERATION
FOOT BRAKE
BR03G±06
When the brake pedal is depressed, a vacuum builds up in the booster whi\
ch amplifies the pedal force,
pressing on the piston in the master cylinder. The piston movement raises the hydraulic pressure in the
cylinder. This hydraulic pressure is then applied to each respective brake cylin\
der, and acts to press the
brake pads against the rotating discs. The resulting friction converts the ro\
tational energy to thermal ener-
gy, stopping the vehicle.
BR±2±
BRAKE SYSTEM OPERATION
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TROUBLESHOOTING
How to proceed with troubleshooting
Perform troubleshooting in accordance with the procedure on the followin\
g pages.

CUSTOMER PROBLEM ANALYSIS
Using the customer problem analysis check sheet for reference, ask the c\
ustomer in as much detail as
possible about the problem.
CHECK AND CLEAR THE DIAGNOSTIC TROUBLE CODES (PRECHECK)
If the ABS warning light lights up, and the ABS does not operate, the ECU \
stores diagnostic trouble codes
corresponding to the problem in memory.
Before confirming the trouble, 1st check the diagnostic trouble codes for any \
malfunction codes stored in
memory. When there are malfunction codes, make a note of them, then clear them \
and proceed to ª  Prob-
lem Symptom Confirmationº.
 PROBLEM SYMPTOM CONFIRMATION,  SYMPTOM SIMULATION
Confirm the problem symptoms. If the problem does not reoccur, simulate the problem by initially checking
the circuits indicted by the diagnostic trouble code in step , using ªProblem simulation methodº.
 DIAGNOSTIC TROUBLE CODE CHECK
Check the diagnostic trouble codes. If a malfunction code is output, proceed \
to ª  Diagnostic Trouble
Code Chartº. If the normal code is output, proceed to ª  Problem Symptoms Chartº. Be sure to proceed
to ª  diagnostic Trouble Code Chartº after steps and  are completed.
If troubleshooting is attempted only by following the malfunction code sto\
red in the memory, errors could
be made in the diagnosis.
 DIAGNOSTIC TROUBLE CODE CHART
If a malfunction code is confirmed in the diagnostic trouble code check,\
proceed to the inspection proce-
dure indicated by the matrix chart for each diagnostic trouble code.
 PROBLEM SYMPTOMS CHART
If the normal code is confirmed in the diagnostic trouble code check, perf\
orm inspection in accordance with
the inspection order in the problem symptoms chart.
 CIRCUIT INSPECTION
Proceed with diagnosis of each circuit in accordance with the inspection\
order confirmed in  and .
Determine whether the cause of the problem is in the sensor, actuators, wire harness and connectors or
the ECU.
\b SENSOR CHECK
Use the ABS warning light to check if each of the signals from speed sensors are being input correctly to
the ECU. Instructions for this check are given in the circuit inspection.
[10] REPAIRS
After the cause of the problem is located, perform repairs by following the i\
nspection and replacement pro-
cedures in this manual.
[11] CONFIRMATION TEST After completing repairs, confirm not only that the malfunction is eliminated\
, but also conduct a test drive
to make sure the entire ABS system is operating correctly. (In vehicles with the TRAC system, also check
the TRAC system.)
BR±72
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
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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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PISTON AND CONNECTING ROD
ASSEMBLY
EG0C1±07
1. ASSEMBLE PISTON AND CONNECTING ROD
(a) Using a small screwdriver, install a new snap ring on one side
of the piston pin hole.
(b) Gradually heat the piston to about 60
C (140
F).
(c) Coat the piston pin with engine oil.
(d) Position the piston front mark with respect to the outside mark
on the connecting rod as shown in the diagram.
NOTICE: The installation direction of the piston and con-
necting rod are different for the RH and LH banks. The RH
piston is marked with ªRº, the LH piston with ªLº.
(e) Align the piston pin holes of the piston and connecting rod,
and push in the piston pin with your thumb.
(f) Using a small screwdriver, install a new snap ring on the other
side of the piston pin hole.
±
1UZ±FE ENGINE ENGINE MECHANICALEG±177
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ASSEMBLY OF PISTON AND
CONNECTING ROD ASSEMBLIES
1. ASSEMBLE PISTON AND CONNECTING ROD(a) Using a small screwdriver, install a new snap ring on one
side of the piston pin hole.
(b) Gradually heat the piston to about 60 °C (140 °F).
(c) Position the piston front mark with respect to the outside
mark on the connecting rod as shown in the diagram.
NOTICE: The installation direction of the piston and con-
necting rod are different for the RH and LH banks. The RH
piston is marked with ºRº, the LH piston with ºLº.
(d) Align the piston pin holes of the piston and connecting rod, and push in the piston pin with your thumb.
(e) Using a small screwdriver, install a new snap ring on the
other side of the piston pin hole.
EM±154
±
ENGINE MECHANICAL Cylinder Block
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(d) Hand±lap the valve and valve seat with an abrasivecompound.
(e) After hand±lapping, clean the valve and valve seat.
9. INSPECT VALVE SPRINGS (a) Using a steel square, measure the squareness of thevalve spring.
Maximum squareness: 2.0 mm (0.079 in.)
If deviation is greater than maximum, replace the valve
spring.
(b) Using vernier calipers, measure the free length of the
valve spring.
Free length:
Pink painted mark 41.74 mm (1.6433 in.)
White painted mark 41.50 mm (1.6339 in.)
If the free length is not as specified, replace the valve spring.
(c) Using a spring tester, measure the tension of the valvespring at the specified installed length.
Installed tension:
186±206 N (19±21 kgf, 42±46 lbf) at 34.5 mm (1.358 in.)
If the installed tension is not as specified, replace the valve
spring.
10. INSPECT CAMSHAFTS AND BEARINGS
A. Inspect camshaft for runout (a) Place the camshaft on V±blocks.
(b) Using a dial indicator, measure the circle runout at the
center journal.
Maximum circle runout: 0.08 mm (0.0031 in.)
If the circle runout is greater than maximum, replace the cam-
shaft.
EM±48
±
ENGINE MECHANICAL Cylinder Head
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(2) If the seating is too low on the valve face, use 755
and 45 5 cutters to correct the seat.
(d) Hand±lap the valve and valve seat with an abrasive compound.
(e) After hand±lapping, clean the valve and valve seat.
9. INSPECT VALVE SPRINGS (a) Using a steel square, measure the squareness of thevalve spring.
Maximum squareness: 2.0 mm (0.079 in.)
If squareness is greater than maximum, replace the valve
spring.
(b) Using a vernier caliper, measure the free length of the
valve spring.
Free length: 43.6 mm (1.717 in.)
If the free length is not as specified, replace the valve spring.
(c) Using a spring tester, measure the tension of the valvespring at the specified installed length.
Installed tension (at 32.9 mm (1.295 in.):
186±206 N (19.0±21.0 kgf, 41.9±46.3 lbf)
If the installed tension is not as specified, replace the valve
spring.
EM±84
±
ENGINE MECHANICAL Cylinder Heads
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