check engine light LEXUS SC400 1991 Service Workshop Manual

PRECAUTIONS
1. Before working on the fuel system, disconnect the cablefrom negative (±) terminal of the battery.
HINT: Any diagnostic code retained by the computer will be
erased when the battery terminal is removed. Therefore, if
necessary, read the diagnosis before removing the battery
terminal.
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 negative (±) terminal
cable is disconnected from the battery.
2. Do not smoke or work on open flame when working on the fuel system.
3. Keep gasoline away from rubber or leather parts.
INSPECTION PRECAUTIONS
MAINTENANCE PRECAUTIONS
1. CHECK CORRECT ENGINE TUNE±UP (See page EM±8)
2. PRECAUTIONS WHEN CONNECTING GAUGE (a) Use the battery as the power source for the timing light,tachometer, etc.
(b) Connect the test probe of a tachometer to the terminal IG of the check connector.
3. IN EVENT OF ENGINE MISFIRE, FOLLOWING PRECAUTIONS SHOULD BE TAKEN
(a) Check proper connection of battery terminals, etc.
(b) Handle high±tension cords carefully.
(c) After repair work, check that the ignition coil terminalsand all other ignition system lines are reconnected
securely.
(d) When cleaning the engine compartment, be especially careful to protect the electrical system from water.
4. PRECAUTIONS WHEN HANDLING OXYGEN SENSOR (a) Do not allow oxygen sensor to drop or hit against anobject.
(b) Do not allow the sensor to come into contact with water.
FI±12
± Precautions, Inspection PrecautionsEFI SYSTEM
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IF VEHICLE IS EQUIPPED WITH MOBILE
RADIO SYSTEM (HAM, CB, ETC.)
The ECU has been designed so that it will not be affected by out-
side interference. However, if your vehicle is equipped with a CB
radio transceiver, etc. (even one with about 10 W output), it may,
at times, have an effect upon ECU operation, especially if the an-
tenna and feeder are installed nearby.
Therefore, observe the following precautions:
1. Install the antenna as far away as possible from the ECU. The
ECU is located on the floor panel on the passenger side so
the antenna should be installed at the rear of the vehicle.
2. Keep the antenna feeder as far away as possible from the ECU wires±at least 20 cm (7.87 in.)±and, especially, do not
wind them together.
3. Check that the feeder and antenna are properly adjusted.
4. Do not equip your vehicle with a powerful mobile radio
system.
5. Do not open the cover or the case of the ECU unless absolutely necessary. (If the IC terminals are touched, the IC
may be destroyed by static electricity.)
AIR INDUCTION SYSTEM
1. Separation of the engine oil dipstick, oil filler cap, PCV hose,
etc. may cause the engine to run out of tune.
2. Disconnection, looseness or cracks in the parts of the air induction system between the throttle body and cylinder
head will cause air suction and cause the engine to run out
of tune.
ELECTRONIC CONTROL SYSTEM
1. Before removing EFI wiring connectors, terminals, etc., firstdisconnect the power by either turning the ignition switch
OFF or disconnecting the battery terminals.
HINT: Always check the diagnosis code before disconnecting
the battery terminals.
2. When installing the battery, be especially careful not to
incorrectly connect the positive (+) and negative (±) cables.
3. Do not permit parts to receive a severe impact during removal or installation. Handle all EFI parts carefully, especially the
ECU.
4. Do not be careless during troubleshooting as there are numerous transistor circuits and even slight terminal contact
can cause further troubles.
5. Do not open the ECU cover.
6. When inspecting during rainy weather, take care to prevent entry of water. Also, when washing the engine compartment,
prevent water from getting on the EFI parts and wiring
connectors.
7. Parts should be replaced as an assembly. FI±13
EFI SYSTEM
± Inspection Precautions
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9. INSTALL DRIVE BELT IDLER PULLEYInstall the idler pulley and cover plate with the pulley bolt.
Torque: 37 N Vm (380 kgf Vcm, 27 ft Vlbf)
10. INSTALL NO.3 TIMING BELT COVERS
(See steps 5 to 9 and 11 on pages IG±17 to 19)
11. CONNECT RADIATOR HOSE TO WATER INLET
12. 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
13. FILL ENGINE WITH COOLANT (See page CO±6)
14. WARM UP ENGINE Allow the engine to warm up to normal operating tempera-
ture.
15. CONNECT TACHOMETER Connect the tester probe of a tachometer to terminal IG
of
the check (ºDIAGNOSISº) connector.
HINT: Set the tachometer to the 4±cylinder range.
NOTICE:
w Never allow the tachometer tester probe to touch ground
as it could result in damage to the igniter and/or ignition
coil.
w As some tachometers are not compatible with this
ignition system, we recommend that you confirm the
compatibility of your unit before use.
16. CHECK IGNITION TIMING
(a) Using SST, connect terminals TE1 and E1 of the check(ºDIAGNOSISº) connector.
SST 09843±18020
(b) C onnect the tester probe of a timing light to the
high±tension cord for No.6 cylinder.
IG±28
±
IGNITION SYSTEM Distributor
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(c) Check the ignition timing.
Ignition timing: 8±125 BTDC @ idle
(Transmission in neutral range)
If the ignition timing is not as specified, check that following
conditions are normal: w Throttle valve fully closed
w Continuity between terminals IDL1 and E2 of the
throttle position sensor (See page FI±73)
w Valve timing (See page EM±51)
(e) Remove the SST from the check connector.
SST 09843±18020
17. DISCONNECT TACHOMETER AND TIMING LIGHT FROM ENGINE
18. INSTALL UPPER HIGH±TENSION CORD COVER (See step 10 on pages IG±18 and 19)
±
IGNITION SYSTEM DistributorIG±29
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(d) Lightly screw the oil filter into place, and tighten it untilthe gasket contacts the seat.
(e) Using SST, tighten it an additional 3/4 turn.
SST 09228±07500
3. FILL WITH ENGINE OIL (a) Clean and install the oil drain plug with a new gasket.
Torque: 45 N Vm (450 kgf Vcm, 33 ft Vlbf)
(b) Fill with fresh engine oil.
Oil grade: See page LU±5
Capacity:
Drain and refill w/ 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 5.2 liters (5.5 US qts, 4.6 lmp. qts)
(c) Reinstall the oil filler cap.
4. START ENGINE AND CHECK FOR LEAKS
5. RECHECK ENGINE OIL LEVEL (See page LU±5)
LU±8
±
LUBRICATION SYSTEM Replacement of Engine Oil and Oil Filter
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DISASSEMBLY OF OIL PUMP
(See Components on page LU±12)
1. REMOVE RELIEF VALVE (a) Slighty mount the pump body in a vise.
(b) Remove the plug, gasket, compression spring and reliefvalve.
NOTICE: Be careful not to damage the pump body.
2. REMOVE DRIVE AND DRIVEN ROTORS Remove the ten screws, pump body cover, the drive and
driven rotors.
INSPECTION OF OIL PUMP
1. INSPECT RELIEF VALVECoat the valve with engine oil and check that it falls smoothly
into the valve hole on 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 The marks on the rotors must face up.
B. Inspect rotor tip clearance Using a feeler gauge, measure the clearance between the
drive and driven rotors.
Standard tip clearance: 0.310±0.490 mm
(0.0122±0.0193 in.)
Maximum tip clearance: 0.53 mm (0.0209 in.)
If the tip clearance is greater than maximum, replace the ro-
tors as a set.
±
LUBRICATION SYSTEM Oil PumpLU±13
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GENERAL MAINTENANCE
MA00M±03
There are the maintenance and inspection
items which are considered to be the owner's
responsibility. They can be performed by the
owner or be can have them done at a service
shop. These items include those which should
be checked on a daily basis, those which, in
most cases, do not require (special) tools and
those which are considered to be reasonable
for the owner to perform. Items and procedures
for general maintanance are as follows:
MA00P±04
OUTSIDE VEHICLE
1. TIRES
(a) Check the pressure with a gauge. Adjust ifnecessary.
(b) Check for cuts, damage or excessive wear.
2. WHEEL NUTS Wheel checking the tires, check the nuts for
looseness or for missing nuts. If necessary,
tighten them.
3. TIRE ROTATION It is recommended that tires be rotated every
12,000 km (7,500 miles).
4. WINDSHIELD WIPER BLADES Check for wear or cracks whenever they do not
wipe clean. Replace if necessary.
5. FLUID LEAKS
(a) Check underneath for leaking fuel, oil, water or
other fluid.
(b) If you smell gasoline fumes or notice any leak, have the cause found and corrected.
6. DOORS AND ENGINE HOOD
(a) Check that all doors including the trunk lid operate smoothly, and that all latches lock
securely.
(b) Check that the engine hood secondary latch secures the hood from opening when the
primary latch is released.
MA00R±05
INSIDE VEHICLE
7. LIGHTS
(a) C h e c k t h a t t h e h eadlights, stop lights,
tail±lights, turn signal lights, and other lights
are all working. (b) Check the headlight aiming.
8. WARNING LIGHT AND BUZZERS
Check that all warning lights and buzzers func-
tion properly.
9. HORN Check that it is working.
10. WINDSHIELD GLASS
Check for scratches, pits or abrasions.
11. WINDSHIELD WIPER AND WASHER
(a) Check operation of the wipers and washer.
(b) Check that the wipers do not streak.
12. WINDSHIELD DEFROSTER Check that the air comes out from the defroster
outlet when operating the heater air condition-
er at defroster mode.
13. REAR VIEW MIRROR
Check that it is mounted securely.
14. SUN VISORS Check that they move freely and are mounted
securely.
15. STEERING WHEEL Check that it has the specified freeplay. Be
alert for changes in steering condition, such as
hard steering, excessive freeplay or strange
noise.
16. SEATS
(a) Check that all front seat controls such as seat adjusters, seatback recliner, etc. operate
smoothly.
(b) Check that all latches lock securely in any position.
(c) Check that the locks hold securely in any latched position.
(d) Check that the head restraints move up and
down smoothly and that the locks hold securely
in ay latches position.
(e) For folding±down rear seat backs, check that the latches lock securely.
17. SEAT BELTS
(a) Ch e ck th a t th e se a t be lt syste m su ch as buckles, retractors and anchors operate
properly and smoothly.
(b) Check that the belt webbing is not cut, frayed,
worn or damaged.
18. ACCELERATOR PEDAL Check the pedal for smooth operation and un-
even pedal effort or catching.
±
MAINTENANCE (1UZ ± FE)MA±19
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(b) Check that the timing marks of the camshaft timingpulleys and timing belt rear plates aligned.
If not, turn the crankshaft one revolution (360 5).
27. REMOVE TIMING BELT TENSIONER HINT:
w(Re±using timing belt)
If the installation marks have disappeared, before re-
moving the timing belt, place new installation marks on
the timing belt to match the timing marks of the camshaft
timing pulleys, and place a new installation mark on the
timing belt to match the end of the hydraulic pump.
w (When replacing timing belt tensioner only)
To avoid meshing of the timing pulley and timing belt, se-
cure one of them with string. And place matchmarks on
the timing belt and RH camshaft timing pulley.
Alternately loosen the two bolts, and remove them, the ten-
sioner and dust boot.
28. DISCONNECT TIMING BELT FROM CAMSHAFT TIMING PULLEYS
(a) Using SST, loosen the tension between the LH and RHcamshaft timing pulleys by slightly turning the LH
camshaft timing pulley clockwise.
SST 09278±54012
±
ENGINE MECHANICAL Timing BeltEM±41
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(d) Using SST, align the timing marks of the LH camshaftpulley and timing belt rear plate.
SST 09278±54012
(e) Check that the timing belt has tension between the crankshaft timing pulley and LH camshaft timing pulley.
14. INSTALL TIMING BELT TO RH CAMSHAFT TIMING PULLEY
(a) Remove any oil or water on the RH camshaft timing andwater pump pulley, and keep them clean.
(b) Using SST, slightly turn the RH camshaft timing pulley clockwise. Align the installation mark on the timing belt
with the timing mark of the camshaft timing pulley, and
hang the timing belt on the RH camshaft timing pulley.
SST 09278±54012
(c) Using SST, align the timing marks of the RH camshaft pulley and timing belt rear plate.
SST 09278±54012
(d) Check that the timing belt has tension between the RH
camshaft timing pulley and LH camshaft pulley.
15. SET TIMING BELT TENSIONER (a) Using a press, slowly press in the push rod using981±9,807 N (100±1,000 kgf, 220±2,205 lbf) of
pressure.
(b) Align the holes of the push rod and housing, pass a 1.27
mm hexagon wrench through the holes to keep the
setting position of the push rod.
(c) Release the press.
(d) Install the dust boot to the tensioner.
EM±50
±
ENGINE MECHANICAL Timing Belt
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(d) Check the valve overall length.
Standard overall length:Intake 94.95 mm (3.7382 in.)
Exhaust 96.90 mm (3.8150 in.)
Minimum overall length: Intake 94.45 mm (3.7185 in.)
Exhaust 96.40 mm (3.7953 in.)
If the overall length is less than minimum, replace the valve.
(e) Check the surface of the valve stem tip for wear.
If the valve stem tip is worn, resurface the tip with a grinder
or replace the valve.
NOTICE: Do not grind off more than the minimum overall
length.
8. INSPECT AND CLEAN VALVE SEATS (a) Using a 455 carbide cutter, resurface the valve seats.
Remove only enough metal to clean the seats.
(b) Check the valve seating position.
Apply a thin coat of prussian blue (or white lead) to the valve
face. Lightly press the valve against the seat. Do not rotate
the valve.
(c) Check the valve face and seat for the following:w If blue appears 3605 around the face, the valve is
concentric. If not, replace the valve.
w If blue appears 3605 around the valve seat, the
guide and face are concentric. If not, resurface the
seat.
w Check that the seat contact is on the middle of the
valve face with the following width:
1.0±1.4 mm (0.039±0.055 in.)
If not, correct the valve seats as follows:
(1) If the seating is too high on the valve face, use 30 5
and 45 5 cutters to correct the seat.
±
ENGINE MECHANICAL Cylinder HeadsEM±83
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