Lexus SC300 / Lexus SC400. Manual - part 341

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

(b)  Install the EGR valve with the two nuts.

Torque: 18 N

⋅

m (185 kgf

⋅

cm, 13 ft

⋅

lbf)

(c)  Connect the following hoses:

(1)  Water by–pass hose (from ISC valve) to the EGR

valve

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

joint) to the EGR valve

8. 

RECONNECT EGR VALVE CONNECTOR

9.  RECONNECT CABLE TO NEGATIVE TERMINAL OF

BATTERY

10.  REFILL WITH ENGINE COOLANT (See page 

CO–7

)

INSPECTION OF EGR VALVE
(Exc. USA Spec.)

1. 

DRAIN ENGINE COOLANT (See page 

CO–6

)

2. 

REMOVE EGR VALVE
(a)  Disconnect the following hoses:

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

modulator

(3)  Vacuum hose (from EGR vacuum modulator) f

rom EGR valve

(4)  Water by–pass hose (from ISC valve) from the 

EGR valve

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

joint) from the EGR valve

(b)  Disconnect the vacuum modulator bracket from the

EGR valve.

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

EC–24

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EMISSION CONTROL SYSTEMS

Exhaust Gas Recirculation (EGR) System