Lexus ES300 (2002 year). Service 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 

05-178

)

NG

REPAIR OR REPLACE

OK

3

CHECK E.F.I. CIRCUIT OPENING RELAY ASSY (See page 

10-2

)

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 

11-4

)

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 

05-178

)

NG

REPAIR OR REPLACE

OK