check engine LEXUS SC400 1991 Service Repair Manual

OIL PRESSURE CHECK
1. CHECK ENGINE OIL QUALITYCheck the oil for deterioration, entry of water, discoloring or
thinning.
If the quality is poor, replace the oil.
Oil grade: API grade SG, Energy±Conserving II multi- grade. Recommended viscosity is as shown,
with SAE 5W±30 being the preferred engine
oil.
2. CHECK ENGINE OIL LEVEL The oil level should be between the ºLº and ºFº marks on the
dipstick.
If low, check for the leakage and add oil up to ºFº mark.
3. REMOVE ENGINE UNDER COVER
4. REMOVE OIL PRESSURE SWITCH, AND INSTALL OIL PRESSURE GAUGE
5. WARM UP ENGINE
Allow the engine to warm up to normal operating tempera-
ture.
6. CHECK OIL PRESSURE
Oil pressure:
At idling 29 kPa (0.3 kgf/cm
2, 4.3 psi)
or more
At 3,000 rpm 294±588 kPa (3.0±6.0 kg/cm
2, 43±85 psi)
7. REMOVE OIL PRESSURE GAUGE AND REINSTALL OILPRESSURE SWITCH
Apply adhesive to two or three threads of the oil pressure
switch.
Adhesive: Part No. 08833±00080, THREE BOND 1344,
LOCTITE 242 or equivalent
8. START ENGINE AND CHECK FOR LEAKS
9. REINSTALL ENGINE UNDER COVER
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LUBRICATION SYSTEM Oil Pressure CheckLU±5
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(d) Tighten the oil filter by hand until the rubber gasketcontacts the seat of the filter mounting. Then using SST,
give it an additional 3/4 turn to seat the oil filter.
SST 09228±07500
3. FILL WITH ENGINE OIL (a) Clean and install the oil drain plug with a new gasket.
Torque: 25 N Vm (250 kgf Vcm, 18 ft Vlbf)
(b) Fill with new engine oil.
Oil grade: See page LU±5
Capacity: Drain and refillw/ Oil filter change
4.8 liters (5.1 US qts, 4.2 lmp. qts)
w/o Oil filter change 4.5 liters (4.8 US qts, 4.0 lmp.qts)
Dry fill 6.0 liters (6.3 US qts, 5.3 lmp. qts)
(c) Reinstall the oil filler cap.
4. START ENGINE AND CHECK FOR LEAKS
5. RECHECK ENGINE OIL LEVEL (See page LU±5)
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LUBRICATION SYSTEM Replacement of Engine Oil and Oil FilterLU±7
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INSPECTION OF OIL PUMP
1. INSPECT RELIEF VALVECoat the valve with engine oil and check that it falls smoothly
into the valve hole by its own weight.
If it doesn't, replace the relief valve. If necessary, replace the
oil pump assembly.
2. INSPECT DRIVE AND DRIVEN ROTORS
A. Place drive and driven rotors into oil pump body Face the mark of the rotors upward.
B. Inspect rotor tip clearance Using a feeler gauge, measure the clearance between the
drive and driven rotors.
Standard tip clearance: 0.110±0.240 mm
(0.0043±0.0094 in.)
Maximum tip clearance: 0.35 mm (0.0138 in.)
If the tip clearance is greater than maximum, replace the ro-
tors as a set.
C. Inspect rotor side clearance Using a feeler gauge and precision straight edge, measure
the clearance between the rotors and precision straight
edge.
Standard side clearance: 0.030±0.090 mm
(0.0012±0.0035 in.)
Maximum side clearance: 0.15 mm (0.0059 in.)
If the side clearance is greater than maximum, replace the ro-
tors as a set. If necessary, replace the oil pump assembly.
D. Inspect rotor body clearance Using a feeler gauge, measure the clearance between the
driven rotor and pump body.
Standard body clearance: 0.100±0.175 mm
(0.0039±0.0069 in.)
Maximum body clearance: 0.30 mm (0.0118 in.)
If the body clearance is greater than maximum, replace the
rotors as a set. If necessary, replace the oil pump assembly.
E. Remove drive and driven rotors
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LUBRICATION SYSTEM Oil PumpLU±13
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24. CONNECT CONTROL CABLES TO THROTTLE BODYConnect the following hoses:(1) Accelerator cable
(2) A/T throttle control cable
(3) (w/ Cruise Control System) Cruise control actuator cable
25. INSTALL THROTTLE BODY COVER Install the throttle body cover and hose clamp with the two
bolts and cap nut.
26. C O N N E C T C A B L E TO N E G AT I V E T E R M I N A L O F BATTERY
27. FILL WITH ENGINE COOLANT (See page CO±7)
28. CHECK THAT ENGINE STARTS
ST±34
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STARTING SYSTEM Starter
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STARTER RELAY
INSPECTION OF STARTER RELAY
1. DISCONNECT CABLE FROM NEGATIVE TERMINAL OFBATTERY
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 STATER RELAY LOCATION: In the engine compartment relay box.
3. INSPECT STARTER RELAY
A. Inspect relay continuity
(a) Using an ohmmeter, check that there is continuitybetween terminals 1 and 2.
(b) Check that there is no continuity between terminals 3 and 5.
If continuity is not as specified, replace the relay.
B. Inspect relay operation (a) Apply battery voltage across terminals 1 and 2.
(b) Using an ohmmeter, check that there is continuitybetween terminals 3 and 5.
If operation is not as specified, replace the relay.
4. REINSTALL STARTER RELAY
5. RECONNECT CABLE TO NEGATIVE TERMINAL OF BATTERY
NEUTRAL START SWITCH
(See AT section)
THEFT DETERRENT SYSTEM
(See BE section)
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STARTING SYSTEM Starter Relay, Neutral Start Switch, Theft Deterrent
SystemST±35
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HOW TO PROCEED WITH TROUBLESHOOTING
The Engine Control System broadly consists of the sensors, ECU and actuator\
s. The ECU receives signals from
various sensors, judges the operating conditions and determines the opti\
mum injection duration, timing, ignition
timing and idle speed.
In general, the Engine Control System is considered to be a very intricate\
system to troubleshoot. But, the fact
is that if you proceed to inspect the circuit one by one following the p\
rocedures directed in this manual, trouble-
shooting of this system is not complex.
This section explains the most ideal method of troubleshooting and tells how\
to carry out the necessary repairs.
[1] CUSTOMER PROBLEM ANALYSISUsing the customer problem analysis check sheet for reference, ask the c\
ustomer in as much details as
possible about the problem.
[2] CHECK AND CLEAR DIAGNOSTIC CODE (PRECHECK) Before confirming the problem symptom, first check the diagnostic code and mak\
e a note of any malfunc-
tion code which is output, then clear the code.
HINT: Output of the malfunction code indicates that there is a malfunction in\
the circuit indicated. However,
it does not indicate whether the malfunction is still occurring or occur\
red in the past and returned to normal.
In order to determine this, the problem symptoms should be confirmed in 4 \
first and the diagnostic code
be rechecked in [6].
Accordingly, if troubleshooting is begun based on the malfunction code only in diag\
nostic code check in
[2] , it could result in a misdiagnosis, leading to troubleshooting of circuits which are normal \
and making
it more difficult to locate the cause of the problem.
[3] SETTING THE TEST MODE DIAGNOSIS, [4] PROBLEM SYMPTOM CONFIRMATION, [5] SYMPTOM SIMULATION
In order to find out the trouble more quickly, set the diagnosis check in test mode and with higher sensing
ability of the ECU, confirm the problem symptoms. If the trouble does not reappear, use the symptom simu-
lation method to make sure the trouble is reproduced.
[6] DIAGNOSTIC CODE CHECK IN TEST MODE Check the diagnostic code in test mode. If the malfunction code is output, pr\
oceed to ºstep [8] Diagnostic
Code Chartº. If the normal code is output, proceed to ºstep [7] Basic Inspectionº.
[7] BASIC INSPECTION Carry out basic inspection such as the spark check and fuel pressure che\
ck, etc.
[8] DIAGNOSTIC CODE CHART If the malfunction code is displayed, proceed to inspect the circuit ind\
icated by the chart for each code.
[9] MATRIX CHART OF PROBLEM SYMPTOMS If the normal code is displayed in the diagnosis in test mode, perform tro\
ubleshooting according to the in-
spection order in the Matrix Chart of Problem Symptoms.
[10] PARTS INSPECTION When the Matrix Chart of Problem Symptoms instructs to check the parts, proc\
eed to parts inspection sec-
tion included in this manual.
[11] CIRCUIT INSPECTION Determine if the malfunction is the sensor, actuator, wire harness, connector or the ECU.
TR±2
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ENGINE TROUBLESHOOTING How to Proceed with Troubleshooting
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[12] CHECK FOR MOMENTARY INTERRUPTIONBy performing the check for momentary interruption, the place where moment\
ary interruptions or momen-
tary shorts are occurring due to poor contacts can be isolated.
[13] ADJUSTMENT, REPAIR After the cause of the problem is located, perform adjustment or repairs\
by following the inspection and
replacement procedures in this manual.
[14] CONFIRMATION TEST After completing adjustment or repairs, confirm not only that the malfunction\
is eliminated, but also conduct
a test drive, etc., to make sure the entire Engine Control System is oper\
ating normally.
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ENGINE TROUBLESHOOTING How to Proceed with TroubleshootingTR±3
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How to Proceed with Troubleshooting Using Volt/Ohm Meter
and TCCS Checker
For the explanation of steps [1] ~ [6], [8] and [10] ~ [16], see the explan\
ation of steps with the same title on page
TR±2.
[7] [9] CIRCUIT INSPECTION BY CHECKER If the Normal code is displayed in the diagnostic code check, connect the \
checker to the vehicle and check
all the circuits which can be inspected using the checker.
If a malfunctioning circuit is then detected, proceed to ºCircuit Ins\
pection by Volt/Ohm Meterº and check
the applicable circuit using a volt/ohm meter. Determine if the malfunction is in the sensor, actuator, wire
harness, connector or the ECU. If the malfunctioning circuit cannot be detected u\
sing the checker, proceed
to ºBasic Inspectionº and perform troubleshooting.
If a malfunction code is displayed in the diagnostic code check, use the c\
hecker to inspect the circuit indi-
cated by the diagnostic code chart for the displayed code.
For instructions on how to connect the checker to the vehicle and how to us\
e the checker, please refer to
the Instruction Manual for TCCS checker.
TR±6
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ENGINE TROUBLESHOOTING How to Proceed with Troubleshooting
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CUSTOMER PROBLEM ANALYSIS CHECK SHEET
TR±8±
ENGINE TROUBLESHOOTING Customer Problem Analysis
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DIAGNOSIS SYSTEM
DESCRIPTION
The ECU contains a built±in self±diagnosis system by which
troubles with the engine signal network are detected and a
ºCHECKº engine warning light on the instrument panel lights up.
By analyzing various signals as shown in the later table (See page
TR±14) the Electronic Control Unit (ECU) detects system malfunc-
tions relating to the sensors or actuators.
In the normal mode, the self±diagnosis system monitors 22 (USA
specification vehicles with TRAC control) or 21 (USA (except for
California) and Canadian specification vehicles with TRAC con-
trol) items, indicated by code No. as shown in TR±14. A ºCHECKº
engine warning light informs the driver that a malfunction has been
detected. The light goes off automatically when the malfunction
has been repaired. But the diagnostic code(s) remains stored in
the ECU memory (except for code Nos. 16 and 53). The ECU
stores the code(s) until it is cleared by removing the EFI fuse with
the ignition switch off.
The diagnostic code can be read by the number of blinks of the
ºCHECKº engine warning light when TE1 and E1 terminals on the
TDCL or check connector are connected. When 2 or more codes
are indicated, the lowest number (code) will appear first.
In the test mode, 15 (USA specification vehicles with TRAC con-
trol) or 14 (USA (except for California) and Canadian specification
vehicles with TRAC control) items, indicated by code No. as
shown in TR±14 are monitored. If a malfunction is detected in any
one of the systems indicated by code Nos. 13, 21, 22, 24, 25, 26,
27, 28, 29, 35, 41, 42, 47, 71 and 78 (USA specification vehicles)
or 13, 21, 22, 24, 25, 26, 27, 28, 29, 35, 41, 42, 47 and 78 (USA
(except for California) and Canadian specification vehicles) the
ECU lights the ºCHECKº engine warning light to warn the techni-
cian that malfunction has been detected. In this case, TE2 and E1
terminals on the TDCL should be connected as shown later. (See
page TR±12 ).
In the test mode, even if the malfunction is corrected, the malfunc-
tion code is stored in the ECU memory even when the ignition
switch is off (except code Nos. 43 and 51). This also applies in the
normal mode. The diagnostic mode (normal or test) and the output
of the ºCHECKº engine warning light can be selected by connect-
ing the TE1, TE2 and E1 terminals on the check connector or
TDCL, as shown later.
A test mode function has been added to the functions of the self±
diagnosis system of the normal mode for the purpose of detecting
malfunctions such as poor contact, which are difficult to detect in
the normal mode. This function fills up the selfdiagnosis system.
The test mode can be implemented by the technician following the
appropriate procedures of check terminal connection and opera-
tion described later. (See page TR±12)
TR±10
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ENGINE TROUBLESHOOTING Diagnosis System
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