Lexus SC300 / Lexus SC400. Manual - part 718

(b)  Apply battery voltage across the terminals.
(c)  Check that the air flows from port E to the filter.
If operation is not as specified, replace the VSV.

4. REINSTALL 

VSV

(a)  Install the VSV with the bolt.

Torque: 18 N

⋅

m (185 kgf

⋅

cm, 13 ft

⋅

lbf)

(b)  Connect the following hoses:

(1)  Vacuum hose (from EGR valve) to VSV
(2)  Vacuum hose (from EGR vacuum modulator) to

VSV

(c)  Connect the VSV connector.

5.  RECONNECT CABLE TO NEGATIVE TERMINAL OF

BATTERY

INSPECTION OF EGR VACUUM
MODULATOR (Exc. USA Spec.)

1.  DISCONNECT VACUUM HOSES FROM EGR VACUUM

MODULATOR
Disconnect the three vacuum hoses from ports P, Q and R of
the EGR vacuum modulator.

2. 

INSPECT EGR VACUUM MODULATOR OPERATION
(a)  Block ports P and R with your finger.
(b)  Blow air into port Q, and check that the air passes

through to the air filter side freely.

(c)  Start the engine, and maintain speed at 2,500 rpm.
(d)  Repeat the above test. Check that there is a strong

resistance to air flow.

3. RECONNECT 

VACUUM 

HOSES 

TO 

EGR 

VACUUM

MODULATOR
Connect the three vacuum hoses to the proper locations.

EC–20

–

EMISSION CONTROL SYSTEMS

Exhaust Gas Recirculation (EGR) System

COMPONENTS FOR REMOVAL AND INSTALLATION OF EGR VALVE

–

EMISSION CONTROL SYSTEMS

Exhaust Gas Recirculation (EGR) System

EC–21

INSPECTION OF EGR VALVE 
(USA Spec.)

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 EGR VALVE CONNECTOR

3. 

INSPECT EGR VALVE RESISTANCE
Using an ohmmeter, measure the resistance between termi-
nal B1 (or B2) and other terminals (S1, S2, S3 and S4).

Resistance (Cold): 19.9–23.4 

4. 

DRAIN ENGINE COOLANT (See page 

CO–6

)

5. 

REMOVE EGR VALVE
(a)  Disconnect the following hoses:

(1) Water 

by–pass hose (from ISC valve) from the EGR

valve

(2)  Water by–pass hose (from rear water by–pass

joint) from the EGR valve

(b)  Remove the two nuts, EGR valve and gasket.

6. 

INSPECT EGR VALVE

A.  Visually inspect EGR valve

Check for sticking and heavy carbon deposits.
If a problem is found, replace the EGR valve assembly.

EC–22

–

EMISSION CONTROL SYSTEMS

Exhaust Gas Recirculation (EGR) System

B.  Inspect EGR valve operation

(a)  Remove the three bolts and stepping motor from the

housing.

(b)  Apply battery voltage to terminal B1 (or B2), and while

repeately grounding (*S4)–(S4 and *S3)–(S3 and
*S2)–(S2 and *S1)–(S1 and *S4) in sequence, check
that the valve moves toward the open position.

HINT: Keep the terminal marked with an asterisk (*) grounded
while proceeding to the next grounding.

(c)  Apply battery voltage to terminal B1 (or B2), and while

repeately grounding (*S1)–(S1 and *S2)–(S2 and
*S3)–(S3 and *S4)–(S4 and *S1) in sequence, check
that the valve moves toward the closed position.

HINT:

•

Keep the terminal marked with an asterisk (*) grounded
while proceeding to the next grounding.

•

Perform this operation after opening the valve by
performing step (b) above.

If operation is not as specified, replace the EGR valve assem-
bly.
(d)  Reinstall the stepping motor to the housing with the

three bolts.

7. 

REINSTALL EGR VALVE
(a)  Place a new gasket on the EGR valve adaptor.
NOTICE:

•

Do not touch the adaptor and EGR valve surfaces of the

gasket with your hand.

•

Align the port holes of the gasket and adaptor. Be careful

of the installation direction.

–

EMISSION CONTROL SYSTEMS

Exhaust Gas Recirculation (EGR) System

EC–23