Lexus SC300 / Lexus SC400. Manual - part 627

TERMINALS OF ENGINE & ECT ECU (Cont’d)

Terminal

No.

Symbol

Connection

Terminal

No.

Symbol

Connection

E10– 21

NCO

T/M Input Speed Sensor

E10 – 51

–

22

–

52

HTL2

LH Sub–Oxygen Sensor Heater

23

SP2

No.2 Speed Sensor for ECT

53

HTR2

RH Sub–Oxygen Sensor Heater

24

–

54

–

25

G2

LH (No.2) Cam Position Sensor

55

–

26

G1

RH (No.1) Cam Position Sensor

56

IGT2

No.2 Igniter for RH Bank

27

NE

Engine Speed Sensor

57

IGT1

No.1 Igniter for LH Bank

28

VF2

Check Connector

58

IGF1

No.1 Igniter for LH Bank

29

VF1

Check Connector

59

IGF2

No.2 Igniter for RH Bank

30

–

60

–

31

–

61

–

32

ISC4

ISC Valve

62

–

33

ISC3

ISC Valve

63

IDL2

Sub–Throttle Position Sensor

34

ISC2

ISC Valve

64

IDL1

Throttle Position Sensor

35

ISC1

ISC Valve

65

E2

Sensor Ground

36

*



EGR4

EGR Valve

66

KS

Air Flow Meter

37

*



EGR3

EGR Valve

67

OXR2

38

*



EGR2

EGR Valve

68

OXL2

LH Sub–Oxygen Sensor

39

*



EGR1

EGR Valve

69

E1

ECU Ground

39

*



EGR

VSV for EGR

69

E1

ECU Ground

40

–

70

–

41

VC

Throttle Position Sensor
Air Flow Meter

71

HTL1

LH Main Oxygen Sensor

42

VTA2

Fuel Pump ECU

72

HTR1

RH Main Oxygen Sensor

43

VTA1

A/C Magnet Clutch Relay

73

FPU

VSV for Fuel Pressure Control
Value

44

THW

Water Temp. Sensor

74

*



PAG

VSV for EVAP

45

THA

Intake Air Temp. Sensor

75

–

46

THG

EGR Gas Temp. Sensor

76

NSW

Neutral Start Switch

47

OXR1

RH Main Oxygen Sensor

77

STA

Starter Relay

48

OXL1

LH Main Oxygen Sensor

78

STJ

Cold Start Injector

49

KNK2

RH (No.2) Knock Sensor

79

E02

Power Ground

50

KNK1

LH (No.1) Knock Sensor

80

E01

Power Ground

Engine & ECT ECU Terminals

*

 

USA spec. only

*

 

A/T only

FI–127

EFI SYSTEM   –   Electronic Control System (Engine & ECT ECU)

COMPONENTS FOR REMOVAL AND
INSTALLATION

INSPECTION OF ENGINE & ECT 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. DISCONNECT 

ENGINE & ECT ECU FROM FLOOR PANEL

(a)  Remove the two clips, and pull out the instrument panel

under cover.

FI–128

EFI SYSTEM   –   Electronic Control System (Engine & ECT ECU)

(b)  Take out the front side of the floor carpet.
(c)  Remove the two nuts and protector.

(d) Remove 

the nut, and disconnect the engine & ECT ECU

from the floor panel.

3. 

INSPECT ENGINE & ECT ECU

A.

Install SST (check harness) between engine & ECT ECU
and wiring connectors
HINT:

•

ECU connectors are water–proof and are the bolt type.

•

For water–proof type connectors, in order to measure
the voltage of ECU terminals and the resistance of
connected parts, connect a check harness (SST
09990–01000)  between  the ECU  and wiring
connectors, then perform the inspection.

•

Avoid inserting a tester probe from the other side of
connector as this noticeably reduces the water–proof
ability.

•

Disconnect the ECU connectors by fully loosening the
bolt.

(a)  Remove the bolt, and disconnect the two ECU

connectors.

NOTICE:

•

Do not pull the wiring harness when disconnecting the
connectors.

•

When disconnecting the connector, the ECU’s back–up
power source is cut off, so the malfunction codes, etc.
recorded in the ECU memory are cancelled.

•

Never insert a tester probe or male terminal used for
inspection purposes into the female terminal of the
vehicle wire harness. Otherwise, the female terminal may
be widened, which can reselt in faulty connection.

(b)  Connect SST (check harness) between ECU and wiring

connectors.

SST 09990–01000
HINT: SST (check harness) connector terminals are ar-
ranged the same as those of the ECU.

FI–129

EFI SYSTEM   –   Electronic Control System (Engine & ECT ECU)

B.

Inspect voltage of engine & ECT ECU
Check the voltage between each terminal.

•

Turn the ignition switch ON.

•

Measure the voltage at each terminal.

HINT:

•

Perform all voltage measurements with the connectors
connected.

•

Verify that the battery voltage is 11 V or more when the
ignition switch is ON.

FI–130

EFI SYSTEM   –   Electronic Control System (Engine & ECT ECU)