fuses LEXUS SC300 1991 Service User Guide

ON±VEHICLE INSPECTION
1. INSPECT BATTERY SPECIFIC GRAVITY ANDELECTROLYTE LEVEL
(a) Check the specific gravity of each cell.
Standard specific gravity:
1.27±1.29 when fully charged at 20 5C (68 5F)
If gravity is less than specification, charge the battery.
(b) Check the electrolyte quantity of each cell.
If insufficient, refill with distilled (or purified) water.
HINT: Check the indicator as shown in the illustration.
2. CHECK BATTERY TERMINALS, FUSIBLE LINKS AND FUSES
(a) Check that the battery terminals are not loose orcorroded.
(b) Check the fusible links and fuses for continuity.
H±fuse: ALT 150A AM1 100A
AM2 30A
M±fuse: IG SW 40A
Fuse: IGN 7.5A ENGINE 7.5A
INJ 30A
3. INSPECT DRIVE BELTHINT: A belt tensioner is used, so checking the belt tension
is not necessary.
(a) Visually check the drive belt for excessive wear, frayedcords, etc.
If necessary, replace the drive belt.
HINT:
w Cracks on rib side of a drive belt are considered
acceptable. If the drive belt has chunks missing from the
ribs, it should be replaced.
w The drive belt tension can be released by turning the
belt tensioner counterclockwise. The pulley bolt for the
belt tensioner has a left±hand thread.
±
CHARGING SYSTEM On±Vehicle InspectionCH±5
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wIf the vehicle has been running, wait 5 minutes or more
after the vehicle stops before measuring the battery
voltage.
If the voltage is less than specification, charge the battery.
HINT: Check the indicator as shown in the illustration.
1. C H E C K B AT T E RY S P E C I F I C G R AV I T Y A N D ELECTROLYTE LEVEL
2. CHECK BATTERY TERMINALS AND FUSES
(a) Check that the battery terminals are not loose or corroded.
(b) Check the fuses for continuity.
EG3F9±01
AIR FILTER INSPECTION AND
CLEANING
1. REMOVE AIR FILTER
(a) Open the air cleaner cap.
(b) Remove the air filter.
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1UZ±FE ENGINE ENGINE MECHANICALEG±11
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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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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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ON±VEHICLE INSPECTION
1. INSPECT BATTERY SPECIFIC GRAVITY ANDELECTROLYTE LEVEL
(a) Check the specific gravity of each cell.
Standard specific gravity:
1.27±1.29 when fully charged at 20 5C (68 5F)
If gravity is less than specification, charge the battery.
(b) Check the electrolyte quantity of each cell.
If insufficient, refill with distilled (or purified) water.
HINT: Check the indicator as shown in the illustration.
2. CHECK BATTERY TERMINALS, FUSIBLE LINKS AND FUSES
(a) Check that the battery terminals are not loose orcorroded.
(b) Check the fusible links and fuses for continuity.
H±fuse: ALT 150A AM1 100A
AM2 30A
M±fuse: IG SW 40A
Fuse: IGN 7.5A ENGINE 7.5A
INJ 30A
3. INSPECT DRIVE BELTHINT: A belt tensioner is used, so checking the belt tension
is not necessary.
(a) Visually check the drive belt for excessive wear, frayedcords, etc.
If necessary, replace the drive belt.
HINT:
w Cracks on rib side of a drive belt are considered
acceptable. If the drive belt has chunks missing from the
ribs, it should be replaced.
w The drive belt tension can be released by turning the
belt tensioner counterclockwise. The pulley bolt for the
belt tensioner has a left±hand thread.
±
CHARGING SYSTEM On±Vehicle InspectionCH±5
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Injector Circuit
CIRCUIT DESCRIPTION
The injectors are provided to the intake manifold. They inject fuel into th\
e cylinders based on the
signals from the engine (& ECT) ECU.
Reference INSPECTION USING OSCILLOSCOPE
w With the engine idling measure between terminals #10 ~ 60 and E01 of engine (& ECT) ECU.
HINT: The correct waveform appears as shown in the illustration on the below\
.
DIAGNOSTIC CHART
Check voltage of terminals #10 ~ 60.
Check AM2 and INJ fuses.
Check for open in harness and connector
between ECU and battery.
Check continuity between terminals E01,
E02 and body ground.
Check operation for injectors.
Check and replace ECU. Check for short in all the harness
and components connected to
AM2 and INJ fuses.
Repair or replace harness or
connector.
Replace injector.
TR±128±
ENGINE TROUBLESHOOTING Circuit Inspection
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NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminals #10  60 of engine (& ECT) ECU and body ground.
C
OK
P(2) Connect the Check Harness A. (See page TR±34)
(2) Turn ignition switch on.
Measure voltage between terminals #10 ~ 60 of engine
(& ECT) ECU and body ground.
Voltage: 10 ± 14 V
Go to step
.
2Check AM2 and INK fuses.
C
OK
PRemove AM2 and INJ fuses from fuse block.
Check continuity of AM2 of INJ fuses.
Continuity
Check for short in all the harness and components
connected to AM2 and INJ fuses.
Check for open in harness and connector between
engine (& ECT) ECU and battery.
TR±130±
ENGINE TROUBLESHOOTING Circuit Inspection
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Injector Circuit
CIRCUIT DESCRIPTION
The injectors are provided to the intake manifold. They inject fuel into th\
e cylinders based on the
signals from the engine (& ECT) ECU.
Reference INSPECTION USING OSCILLOSCOPE
w With the engine idling measure between terminals #10 ~ 60 and E01 of engine (& ECT) ECU.
HINT: The correct waveform appears as shown in the illustration on the below\
.
DIAGNOSTIC CHART
Check voltage of terminals #10 ~ 60.
Check AM2 and INJ fuses.
Check for open in harness and connector
between ECU and battery.
Check continuity between terminals E01,
E02 and body ground.
Check operation for injectors.
Check and replace ECU. Check for short in all the harness
and components connected to
AM2 and INJ fuses.
Repair or replace harness or
connector.
Replace injector.
TR±128±
ENGINE TROUBLESHOOTING Circuit Inspection
WhereEverybodyKnowsYourName

NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminals #10  60 of engine (& ECT) ECU and body ground.
C
OK
P(2) Connect the Check Harness A. (See page TR±34)
(2) Turn ignition switch on.
Measure voltage between terminals #10 ~ 60 of engine
(& ECT) ECU and body ground.
Voltage: 10 ± 14 V
Go to step
.
2Check AM2 and INK fuses.
C
OK
PRemove AM2 and INJ fuses from fuse block.
Check continuity of AM2 of INJ fuses.
Continuity
Check for short in all the harness and components
connected to AM2 and INJ fuses.
Check for open in harness and connector between
engine (& ECT) ECU and battery.
TR±130±
ENGINE TROUBLESHOOTING Circuit Inspection
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