tow LEXUS SC400 1991 Service User Guide

B. Inspect EGR valve operation(a) Remove the three bolts and stepping motor from thehousing.
(b) Apply battery voltage to terminal B1 (or B2), and while repeately grounding (*S4)±(S4 and *S3)±(S3 and
*S2)±(S2 and *S1)±(S1 and *S4) in sequence, check
that the valve moves toward the open position.
HINT: Keep the terminal marked with an asterisk (*) grounded
while proceeding to the next grounding.
(c) Apply battery voltage to terminal B1 (or B2), and while repeately grounding (*S1)±(S1 and *S2)±(S2 and
*S3)±(S3 and *S4)±(S4 and *S1) in sequence, check
that the valve moves toward the closed position.
HINT:
w Keep the terminal marked with an asterisk (*) grounded
while proceeding to the next grounding.
w Perform this operation after opening the valve by
performing step (b) above.
If operation is not as specified, replace the EGR valve assem-
bly.
(d) Reinstall the stepping motor to the housing with the three bolts.
7. REINSTALL EGR VALVE (a) Place a new gasket on the EGR valve adaptor.
NOTICE:
w Do not touch the adaptor and EGR valve surfaces of the
gasket with your hand.
w Align the port holes of the gasket and adaptor. Be careful
of the installation direction.
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EMISSION CONTROL SYSTEMS Exhaust Gas Recirculation (EGR) SystemEC±23
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10. REMOVE RH NO.3 TIMING BELT COVERRemove the 3 bolts, timing belt cover and 3 gaskets.
11. DISCONNECT FUEL INLET HOSE FROM LH DELIVERY PIPE
Remove the pulsation damper and 2 gaskets, and discon-
nect the fuel inlet hose from the delivery pipe.
CAUTION:
w Put a shop towel under the delivery pipe.
w Slowly loosen the union bolt.
12. D I S C O N N E C T F U E L R E T U R N H O S E F R O M F U E L
RETURN PIPE
13. DISCONNECT PCV HOSE FROM LH CYLINDER HEAD
14. REMOVE LH NO.3 TIMING BELT COVER
(a) Remove the 4 bolts.
(b) Disconnect the cord grommet from the timing belt cover, and remove the timing belt cover and 3 gaskets.
(c) Remove the cord grommet from the high±tension cord.
15. DISCONNECT HEATER WATER VALVE FROM BODY
(a) Disconnect the VSV connector.
(b) Remove the bolt holding the engine wire clamp to the water valve bracket.
(c) Remove the 2 bolts, and disconnect the water valve and bracket assembly.
16. REMOVE THROTTLE BODY
(a) Disconnect the following connectors: (1) Throttle position sensor connector
(2) w/ TRAC:
Sub±throttle position sensor connector
(3) w/ TRAC:
Sub±throttle actuator connector
EG±16
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1UZ±FE ENGINE ENGINE MECHANICAL
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(b) Remove the bolt, stud bolt and accelerator bracket.
(c) Remove the union bolt, union and 2 gaskets.
(d) Disconnect the following connectors:wCold start injector connector
w VSV connector for fuel pressure control
w Except California:
VSV connector for EGR
(e) Remove the union bolt and 2 gaskets, and disconnect the cold start injector tube from the RH delivery pipe.
CAUTION:
w Put a shop towel under the delivery pipe.
w Slowly loosen the union bolt.
(f) Remove the 2 bolts and gasket, and disconnect the EGR
pipe from the air intake chamber.
(g) Remove the 4 bolts, 8 nut and following parts: (1) VSV for fuel pressure
(2) Except California:VSV for EGR
(3) Transmission throttle cable bracket
(h) Disconnect the DLC1 from the air intake chamber.
(i) Remove the air intake chamber and 4 gaskets.
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1UZ±FE ENGINE ENGINE MECHANICALEG±81
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(j) Remove the 3 bolts, the cold start injector, tube, lead wireassembly and gasket.
19. DISCONNECT HEATER WATER HOSES Disconnect the following hoses:
(1) Water hose from water bypass pipe
(2) Water hose from rear water bypass joint
20. DISCONNECT FUEL INLET HOSE FROM DELIVERY PIPE
Remove the pulsation damper and 2 gaskets, and discon-
nect the fuel inlet hose from the delivery pipe.
CAUTION:
w Put a shop towel under the delivery pipe.
w Slowly loosen the union bolts.
21. D I S C O N N E C T F U E L R E T U R N H O S E F R O M F U E L
RETURN PIPE
22. DISCONNECT EGR PIPE FROM RH CYLINDER HEAD Remove the bolt holding the EGR pipe to the RH cylinder
head, and disconnect the EGR pipe.
23. DISCONNECT ENGINE WIRE FROM INTAKE MANIFOLD Remove the 2 bolts, and disconnect the engine wire protector
from the intake manifold.
EG±82
±
1UZ±FE ENGINE ENGINE MECHANICAL
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21. REMOVE THEFT DETERRENT HORN(a) Disconnect the connector.
(b) Remove the bolt and theft deterrent horn.
HINT: Remove the deterrent horn when the valve clearance
is adjusted for the front portion of the exhaust camshaft on
the LH cylinder head.
22. ADJUST VALVE CLEARANCE (a) Remove the adjusting shim.w Turn the crankshaft, and position the cam lobe of
the camshaft on the adjusting valve upward.
w Position the hole of the adjusting shim toward the
spark plug side.
w Press down the valve lifter with SST (A), and place
SST (B) between the camshaft and valve lifter
flange. Remove SST (A).
SST 09248±55011 (09248±05011 (A), 09248±05021 (B))
NOTICE: The valve lifter is made of aluminum, which is
easily scratched. So when setting SST (B), take care not
to scratch the face of the valve lifter.
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ENGINE MECHANICAL Engine Tune±UpEM±17
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(h) Disconnect the following connectors:(1) Two connectors from engine (& ECT) ECU
(2) Connector from ABS & TRAC ECU
(3) Two connectors from TRAC ECU
(4) Four connectors from connector cassette
(5) Connector from A/C control assembly
(i) Pull out the engine wire from the cabin.
14. DISCONNECT PS PIPE FROM ENGINE Remove the two clamp bolts, and disconnect the PS pipe.
15. DISCONNECT HOSE, STARTER WIRE AND GROUND STRAP
(a) Remove the union bolt and two gaskets, disconnect thefuel inlet hose, and suspend the hose union end
upward.
HINT:
w Put a suitable container or shop towel under the fuel
pipe support.
w Slowly loosen the union bolt.
(b) Remove the nut and disconnect the starter wire.
(c) Disconnect the starter wire from the wire clamp.
(d) Disconnect the ground strap from the transmission.
16. (M/T)
DISCONNECT CLUTCH RELEASE CYLINDER FROM TRANS-
MISSION
Remove the two bolts and pull out the release cylinder.
EM±70
±
ENGINE MECHANICAL Cylinder Block
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2. INSPECT ISC VALVE OPERATION(a) Apply battery voltage to terminals B1 and B2, and whilerepeatedly grounding S1±S2±S3±S4±S1 in sequence,
and check that the valve moves toward the closed
position.
(b) Aplly battery voltage to terminals B1 and B2, and while repeatedly grounding S4±S3±S2±S1±S4 in sequence,
and check that the valve moves toward the open
position.
If operation is not as specified, replace the ISC valve.
INSTALLATION OF ISC VALVE
(See Components on page FI±54)
1. INSTALL ISC VALVE
(a) Install a new O±ring on the throttle body.
(b) Install the ISC valve with the two screws.
2. INSTALL THROTTLE BODY (See page FI±45)
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EFI SYSTEM Air Induction System (Idle Speed Control (ISC) Valve)FI±55
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(d) Disconnect the following hoses from the ISC valve:(1) Water by±pass hose (from throttle valve)
(2) Water by±pass hose (from water inlet housing)
(3) Water by±pass hose (from EGR valve)
(e) Remove the two nuts, ISC valve and gasket.
INSPECTION OF ISC VALVE
1. INSPECT ISC VALVE RESISTANCE Using an ohmmeter, measure the resistance between the ter-
minals (B1±S1 and S3, B2±S2 and S4).
Resistance: 10±30

If resistance is not as specified, replace the ISC valve.
2. INSPECT ISC VALVE OPERATION (a) Apply battery voltage to terminals B1 and B2, and whilerepeatedly grounding S1±S2±S3±S4±S1 in sequence,
and check that the valve moves toward the closed
position.
(b) Apply battery voltage to terminals B1 and B2, and while repeatedly grounding S4±S3±S2±S1±S4 in sequence,
and check that the valve moves toward the open
position.
If operation is not as specified, replace the ISC valve.
FI±82
EFI SYSTEM
± Air Induction System (Idle Speed Control (ISC) Valve)
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If there is no pressure, check the following parts:
wFuses
w EFI main relay
w Fuel pump ECU
w Fuel pump
w Engine (& ECT) ECU
w Wiring connections
2. CHECK FUEL PRESSURE (a) Check the battery voltage above 12 volts.
(b) Disconnect the cable from the negative (±) terminal ofthe battery.
CAUTION: Turn the ignition switch to ºLOCKº. Discon-
nect the cable from the negative (±) terminal of the bat-
tery. Wait at least 20 seconds before proceeding with
work.
(c) Remove the union bolt holding the deliver pipe to the No. 1 fuel pipe. Remove the two gaskets.
HINT:
w Put a suitable container or shop towel under the delivery
pipe.
w Slowly loosen the union bolt.
(d) Install the No. 1 fuel pipe and SST (pressure gauge) to the delivery pipe with three new gaskets and the union
bolt.
SST 09268±45012
Torque: 42 N Vm (420 kgf Vcm, 30 ft Vlbf)
(e) Wipe off any splattered gasoline.
(f) Using SST, connect terminals +B and FP of the check
(ºDIAGNOSISº) connector.
SST 09843±18020
(g) Reconnect the cable to the negative (±) terminal of the battery.
±
EFI SYSTEM Fuel System (Fuel Pump)FI±17
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If there is no pressure, check the following parts:w Fuses
w EFI main relay
w Fuel pump ECU
w Fuel pump
w Engine & ECT ECU
w Wiring connections
2. CHECK FUEL PRESSURE (a) Check the battery voltage above 12 volts.
(b) Disconnect the cable from the negative (±) terminal ofthe battery.
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.
(c) (Exc. USA Spec.) Remove the filter from the VSV (for EGR system).
(d) Remove the union bolt holding the LH deliver pipe to the
rear fuel pipe. Remove the two gaskets.
HINT:
w Put a suitable container or shop towel under the cold
start injector pipe.
w Slowly loosen the union bolt.
(e) Install the rear fuel pipe and SST (pressure gauge) to the LH delivery pipe with three new gaskets and the
union bolt.
SST 09268±45012
Torque: 39 N Vm (400 kgf Vcm, 29 ft Vlbf)
(f) Wipe off any splattered gasoline.
(g) (Exc. USA Spec.)
Reinstall the filter to the VSV.
(h) Using SST, connect terminals B and FP of the check (ºDIAGNOSISº) connector.
SST 09843±18020
(i) Reconnect the cable to the negative (±) terminal of the
battery.
FI±18
EFI SYSTEM
± Fuel System (Fuel Pump)
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