Lexus ES300 (2002 year). Manual — part 394
A60853
AM2
FL MAIN
Starter
C/OPN Relay
Park/Neutral
Position SW
ST1
E.F.I. ECU
Relay
ALT
Battery
AM1
ECM
NE
STA
MREL
IGSW
E.F.I.
Ignition SW
AM1
AM2
Fuel Pump
ST2
IG2
IG2
Stater
Relay
(NE Signal)
(STA Signal)
FC
Tr
-
DIAGNOSTICS
SFI SYSTEM (1MZ-FE)
05-173
326
2002 LEXUS ES300 REPAIR MANUAL (RM911U)
FUEL PUMP CONTROL CIRCUIT
CIRCUIT DESCRIPTION
In the diagram below, when the engine is cranked, current flows from terminal ST of the ignition switch to
the starter relay (Marking: ST) coil and also current flows to terminal STA of ECM (STA signal).
When the STA signal and NE signal are input to the ECM, Tr is turned ON, current flows to coil of the circuit
opening relay (Marking: C/OPN), the relay switches on, power is supplied to the fuel pump and the fuel pump
operates.
While the NE signal is generated (engine running), the ECM keeps Tr ON (circuit opening relay ON) and the
fuel pump also keeps operating.
051MW-1 1
A60860
IF3
W-R
Ignition SW
IF6
FC
MREL
ECM
B-W
3
1E
4
G-R
B-R
8
E6
1C
6
7
3
ID1
Engine Room J/B
B-G
FL MAIN
Battery
L-B
ED
W-B
1D
IG2
1A
1B
E6
10
1C
1C
8
B-R
6
8
3
2
5
1
1
3
5
2
5
2
2
1
1
W-R
AM2
E.F.I.
E.F.I.
ECU
Relay
C/OPN
Relay
B-G
L-B
Fuel Pump
J12 J/C
A
4
5
W-B
BC
11
Engine Room R/B
AM2
IG2
05-174
-
DIAGNOSTICS
SFI SYSTEM (1MZ-FE)
327
2002 LEXUS ES300 REPAIR MANUAL (RM911U)
WIRING DIAGRAM
A57009
A53769
FC
E2
-
DIAGNOSTICS
SFI SYSTEM (1MZ-FE)
05-175
328
2002 LEXUS ES300 REPAIR MANUAL (RM911U)
INSPECTION PROCEDURE
When using Hand-held Tester:
1
PERFORM ACTIVE TEST BY CHECK OPERATION OF FUEL PUMP
(a)
Turn the ignition switch ON and push the hand-held tes-
ter main switch ON.
(b)
Use the ACTIVE TEST mode to operate the fuel pump.
(c)
Check that the pulsation damper screw rises up when the
fuel pump is operated by the hand-held tester.
Result: The pulsation damper screw rises up.
OK
CHECK FOR STARTER SIGNAL CIRCUIT
NG
2
CHECK FOR ECM POWER SOURCE CIRCUIT (See page
NG
REPAIR OR REPLACE
OK
3
CHECK E.F.I. CIRCUIT OPENING RELAY ASSY (See page
NG
REPLACE E.F.I. CIRCUIT OPENING RELAY
ASSY
OK
4
INSPECT ECM
(a)
Turn the ignition switch ON.
(b)
Measure the voltage between terminal FC and E2 of the
ECM connector.
Voltage: 9 - 14 V
NG
CHECK HARNESS AND CONNECTOR
OK
A53769
FC
E2
A57009
05-176
-
DIAGNOSTICS
SFI SYSTEM (1MZ-FE)
329
2002 LEXUS ES300 REPAIR MANUAL (RM911U)
5
INSPECT FUEL PUMP (See page
NG
REPLACE FUEL PUMP
OK
6
CHECK HARNESS AND CONNECTOR(CIRCUIT OPENING RELAY - FUEL
PUMP,FUEL PUMP - E2)
NG
REPAIR OR REPLACE HARNESS AND
CONNECTOR
OK
CHECK AND REPLACE ECM
OBDII scan tool (excluding Hand-held Tester):
1
CHECK OPERATION OF FUEL PUMP
(a)
Turn the ignition switch ON.
(b)
Connect between terminal FC and E2 of the ECM con-
nector.
(c)
Check that the pulsation damper screw rises up when
connecting between terminal FC and E2 of the ECM and
E8 connector.
Result: The pulsation damper screw rises up.
OK
CHECK FOR STARTER SIGNAL CIRCUIT
NG
2
CHECK FOR ECM POWER SOURCE CIRCUIT (See page
NG
REPAIR OR REPLACE
OK
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