Lexus SC300 / Lexus SC400. Manual - part 629

•

Disconnect the SST from the wiring connectors.

SST 09990–01000

4. 

REINSTALL ENGINE & ECT ECU TO FLOOR PANEL
(a)  Connect the two ECU connectors.

•

Match the male connector correctly with the female
connector, then press them together.

•

Tighten the bolt.

Make sure the connector is completely connected, by tight-
ening the bolt until there is a clearance of less than 1 mm
(0.04 in.) between bottom of the male connector and end of
the female connector.

(b)  Install the ECU with the bolt.

(c)  Install the ECU protector with the two nuts.
(d)  Install the floor carpet.

(e)  Install the instrument panel under cover with the two clips.

5.  RECONNECT CABLE TO NEGATIVE TERMINAL OF

BATTERY

FI–135

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

Fuel Cut RPM

INSPECTION OF FUEL CUT RPM

1. 

WARM UP ENGINE
Allow the engine to warm up to normal operating
temperature.

2. CONNECT 

TACHOMETER

Connect the test probe of a tachometer to terminal IG  of the
check connector.
NOTICE

•

Never allow the tachometer terminal to touch ground as

it could result in damage to the igniter and/or ignition

coil.

•

As some tachometers are not compatible with this

ignition system, we recommend that you confirm the

compatibility of yours before use.

3. 

INSPECT FUEL CUT OPERATION
(a)  Increase the engine speed to at least 2,500 rpm.
(b)  Check for injector operating noise.
(c)  Check that when the throttle lever is released, injector

operation noise stops momentarily and then resumes.

HINT:

•

The vehicle should be stopped.

•

Measure with the A/C OFF.

Fuel return rpm: 1,400 rpm

4. REMOVE 

TACHOMETER

FI–136

                                –   Electronic Control System (Fuel Cut RPM)

EFI SYSTEM

SERVICE SPECIFICATIONS

SERVICE DATA

Fuel pump

Resistance

0.2 – 3.0 

Cold start
injector

Resistance
Fuel leakage

2 – 4 

One drop or less per minute

Fuel pressure
regulator

Fuel pressure

at no vacuum

265 – 304 kPa
(2.7 – 3.1 kgf/cm

2

, 38 – 44 psi)

Injector

Resistance
Injection volume
Difference between each cylinder
Fuel leakage

13.4 – 14.2 

55 – 70 cc (3.4 – 4.3 cu in.) per 15 sec.
10 cc (0.6 cu in.) or less
One drop or less per minute

Air flow meter

Resistance (THA – E2)

at–20

°

C (–4

°

F)

at 0

°

C (32

°

F)

at 20

°

C (68

°

F)

at 40

°

C (104

°

F)

at 60

°

C (140

°

F)

at 80

°

C (176

°

F)

10 – 20 k

4 – 7 k

2 – 7 k

0.9 – 1.3 k

0.4 – 0.7 k

0.2 – 0.4 k

Throttle body

Throttle body fully closed angle

6

°

Throttle
position

Clearance between

stop screw and lever

Between terminals

Resistance

sensor
(main)

0 mm

0.40 mm
0.65 mm

0 in.

0.016 in.
0.026 in.

VTA1 – E2

IDL1 – E2
IDL1 – E2

VTA1

E2

0.2 – 0.8 k

2.3 k

 or less

Infinity

3 3

10 0 k

Throttle valve fully opened position

–

VTA1 – E2

VC – E2

y

3.3 – 10.0 k

4.0 – 9.0 k

Sub–throttle
position

Clearance between

stop screw and lever

Between terminals

Resistance

sensor
(w/ TRAC)

0 mm

0.30 mm
0.50 mm

0 in.

0.012 in.
0.020 in.

VTA2 – E2

IDL2 – E2
IDL2 – E2

VTA2

E2

0.2 – 0.8 k

2.3 k

 or less

Infinity

3 3

10 0 k

Throttle valve fully opened position

–

VTA2 – E2

VC – E2

y

3.3 – 10.0 k

4.0 – 9.0 k

Sub–throttle
actuator
(w/ TRAC)

Resistance (ACM – A and A, BCM – B and B)

0.5 – 1.0 

ISC valve

Resistance (B1 – S1 and S3, B2 – S2 and S4)

10 – 30 

Cold start
injector time
switch

Resistance STA – STJ

below 15

°

C (59

°

F)

above 30

°

C (86

°

F)

STA – Ground

25 – 45 

65 – 85
25 – 85 

VSV for fuel
pressure
control

Resistance

37 – 44 

FI–137

                                       –   Service Specifications

EFI SYSTEM

SERVICE DATA (Cont’d)

Water temp.
sensor

Resistance

at –20

°

C (–4

°

F)

at 0

°

C (32

°

F)

at 20

°

C (68

°

F)

at 40

°

C (104

°

F)

at 60

°

C (140

°

F)

at 80

°

C (176

°

F)

10 – 20 k

4 – 7 k

2 – 7 k

0.9 – 1.3 k

0.4 – 0.7 k

0.2 – 0.4 k

EGR gas
temp.
sensor

Resistance

at 50

°

C (112

°

F)

at 100

°

C (212

°

F)

at 150

°

C (302

°

F)

69 – 89 k

12 – 15 k

2 – 4 k

Main oxygen
sensor

Heater coil resistance

5.1 – 6.3 

Sub–oxygen
sensor

Heater coil resistance

5.1 – 6.3 

ECU

HINT:

Perform all voltage and resistance measurements with the ECU connected.

Verify that the battery voltage in 11 V or above with the ignition switch is ON.

Voltage

Terminals

Condition

STD voltage (V)

BATT – E1

–

10 – 14

IGSW

+B – E1

+B1

IG SW ON

10 – 14

VC – E2

–

4.0 – 6.0

IDL1

E2

Throttle (or sub–throttle) valve fully closed

1 or less

IDL1
IDL2

– E2

IG SW ON

Throttle (or sub–throttle) valve fully open

10 – 14

VTA1

E2

Throttle (or sub–throttle) valve fully closed

0.1 or less

VTA1

VTA 2

– E2

Throttle (or sub–throttle) valve fully open

3.0 – 6.0

KS – E1

Idling

Pulse generation

THA – E2
THW – E2

Idling

Intake air temp. 20

°

C (68

°

F)

1.0 – 3.0

THW – E2

Idling

Engine coolant temp. 80

°

C (176

°

F)

0.1 – 1.0

STA – E1

Cranking

6.0 or more

#10
#20

E01

IG SW ON

10 – 14

#20
#30
#40

–

E01
E02

Idling

Pulse generation

IGT1
IGT2

– E1

Idling

Pulse generation

FI–138

EFI SYSTEM   –   Service Specifications