Lexus SC300 / Lexus SC400. Service manual — part 626

INSPECTION OF FUEL PUMP ECU

1.

DISCONNECT CABLE FROM NEGATIVE TERMINAL OF
BATTERY
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ”LOCK” position and the negative (–) termi-
nal cable is disconnected from the battery.

2.

REMOVE SEAT CUSHION AND BACK

3.

REMOVE QUARTER TRIM
(a) Disconnect the rear side of the scuff plate by pulling it.

(b) Remove clip A.
(c) Remove the belt hole cover by pulling it.

(d) Remove clip B.
(e) Remove the quarter trim by pulling it.

4.

DISCONNECT FUEL PUMP ECU CONNECTOR

FI–123

EFI SYSTEM – Electronic Control System (Fuel Pump ECU)

5.

INSPECT FUEL PUMP ECU
(a) Connect the cable to the negative (–) terminal of the

battery.

(b) Check the connector on the wiring harness side as

shown in the chart.

Check for

Tester connection

Condition

Specified value

Continuity

E – Ground

–

Continuity

Continuity

DI – Ground

–

Continuity

Voltage

FP

Ground

Sudden racing

12 – 14 V

Voltage

FP – Ground

Idling

8 – 10 V

Voltage

+ B – Ground

IG SW ON

10 – 14 V

Voltage

FPC – Ground

Sudden racing

(1,600 rpm or more)

4 – 6 V

Voltage

FPC Ground

Idling

2.5 V

If circuit is as specified, replace the fuel pump ECU.
(c) Disconnect the cable from the negative (–) terminal of

the battery.

6.

RECONNECT FUEL PUMP ECU CONNECTOR

7.

INSTALL QUARTER TRIM
(a) Attach the upper side of the quarter trim to the quarter

panel.

(b) Install the quarter trim with the four clips.

FI–124

EFI SYSTEM – Electronic Control System (Fuel Pump ECU)

(c) Install the belt hole cover with the two clips.

(d) Install the rear side of the scuff.

8.

REINSTALL SEAT BACK AND CUSHION

9.

RECONNECT CABLE FROM NEGATIVE TERMINAL OF
BATTERY

FI–125

EFI SYSTEM – Electronic Control System (Fuel Pump ECU)

Engine & ECT ECU

TERMINALS OF ENGINE & ECT ECU

Terminal

No.

Symbol

Connection

Terminal

No.

Symbol

Connection

E9 – 1

IGSW

Ignition Switch

E9 – 31

+ B EFI Main Relay

2

SPD

No. 1 Speed Sensor

32

+ B1 EFI Main Relay

3

KD

Kick–Down Switch

33

BATT Battery

4

STP

Stop light Switch

34

A/C A/C Control Assembly

5

–

35

–

6

W

“CHECK” Engine Warning Light

36

–

7

R

Neutral Start Switch

37

TR TRAC ECU

8

–

38

NEO TRAC ECU

9

2

Neutral Start Switch

39

VTO2 TRAC ECU

10

L

Neutral Start Switch

40

VTO1 TRAC ECU

11

AD

CC ECU

E10 – 1

NCO

T/M Input Speed Sensor

12

OD1

CC ECU

2

–

13

–

3

SP2

No. 2 Speed Sensor for ECT

14

–

4

E11 ECU Ground

15

–

5

G2

Cam position Sensor

16

–

6

G1

Cam position Sensor

17

TT

TDCL

7

NF

Engine Speed Sensor

18

P

ECT Pattern Select Switch

8

–

19

TE2

Check Connector

9

S2 ECT Solenoid Value

20

TE1

Check Connector

10

S1 ECT Solenoid Value

21

D1

Fuel Pump ECU

11

–

22

FPC

Fuel Pump ECU

12

–

23

ACMG

A/C Magnet Clutch Relay

13

SLN

No.3 ECT Solenoid Valve

24

M–REL

EFI Main Relay

14

SLU

No.4 ECT Solenoid Valve

25

–

15

–

26

–

16

–

27

–

17

#10 No.3 and No.5 Injectors

28

OD2

O/D Main Relay

18

#20 No.4 and No.6 Injectors

29

–

19

#20 No.2 and No.8 Injectors

30

–

20

#40 No.1 and No.7 Injectors

Engine & ECT ECU Terminals

FI–126

– Electronic Control System (Engine & ECT ECU)

EFI SYSTEM