Lexus SC300 / Lexus SC400. Manual - part 521

(e)  Connect the fuel return pipe to the pressure regulator

with new two gaskets and the union bolt.

Torque: 35 N

⋅

m (360 kgf

⋅

cm, 26 ft

⋅

lbf)

(f)  Tighten the lock nut.

Torque: 29 N

⋅

m (300 kgf

⋅

cm, 22 ft

⋅

lb)

2.  CONNECT VACUUM SENSING HOSE TO FUEL

PRESSURE REGULATOR

3. 

INSTALL RH ENGINE WIRE COVER
(a)  Fit portions A and B of the engine wire cover, matching

them with the lower high–tension cord cover and No.3
timing belt cover.

(d)  Install the engine wire cover with the bolt.

FI–46

EFI SYSTEM   –   Fuel System (Fuel Pressure Regulator)

4. 

INSTALL UPPER HIGH–TENSION CORD COVER
(a)  Fit portion A of the upper high–tension cover, matching

it with the top of the lower high–tension cord cover.

(b)  Push the front side of the high–tension cord cover, and

connect the front side claw groove of the upper
high–tension cord cover to the claw of the lower
high–tension cord cover.

(c)  Install the upper high–tension cord cover with the two

bolts.

5. 

INSTALL INTAKE AIR CONNECTOR
(a)  Connect the end portions of the intake air connector to

the throttle body and air cleaner hose.

(b)  Tighten the two hose clamps.
(c)  Install the bolt holding the intake air connector to the

cylinder head cover.

(d)  Connect the following hoses:

(1)  Air hose to ISC valve
(2) Air 

hose (from PS air control valve) to intake air con-

nector

6.  CONNECT CABLE TO NEGATIVE TERMINAL OF

BATTERY

7. 

CHECK FOR FUEL LEAKS (See page 

FI–16

)

FI–47

EFI SYSTEM   –   Fuel System (Fuel Pressure Regulator)

ENGINE SPEED SENSOR

COMPONENTS FOR REMOVAL AND
INSTALLATION

REMOVAL OF ENGINE SPEED SENSOR

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 ENGINE UNDER COVER

3. 

DISCONNECT ENGINE SPEED SENSOR CONNECTOR

4. 

REMOVE ENGINE SPEED SENSOR
Remove the bolt and engine speed sensor.

INSTALLATION OF ENGINE SPEED
SENSOR

1. 

INSTALL ENGINE SPEED SENSOR

Torque: 6.4 N

⋅

m (65 kgf

⋅

cm, 56 in.

⋅

lbf)

2. 

CONNECT ENGINE SPEED SENSOR CONNECTOR

3. 

INSTALL ENGINE UNDER COVER

4.  CONNECT CABLE TO NEGATIVE TERMINAL OF

BATTERY

IG–30

–

 IGNITION SYSTEM

Engine Speed sensor

IGNITION MAIN RELAY

INSPECTION OF IGNITION MAIN RELAY

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 IGNITION MAIN RELAY
LOCATION: In the engine compartment relay box.

3. 

INSPECT IGNITION MAIN RELAY

A.  Inspect relay continuity

(a)  Using an ohmmeter, check that there is continuity

between terminals 3 and 6.

(b)  Check that there is continuity between terminals 4 and

5.

(c)  Check that there is no continuity between terminals 1

and 2.

If continuity is not as specified, replace the relay.

B.  Inspect relay operation

(a)  Apply battery voltage across terminals 3 and 6.
(b)  Using an ohmmeter, check that there is continuity

between terminals 1 and 2.

(c)  Apply battery voltage across terminals 4 and 5.
(d)  Using an ohmmeter, check that there is continuity

between terminals 1 and 2.

If operation is not as specified, replace the relay.

4. 

REINSTALL IGNITION MAIN RELAY

5.  RECONNECT CABLE TO NEGATIVE TERMINAL OF

BATTERY

–

 IGNITION SYSTEM

Ignition Main Relay

IG–31