Lexus SC300 / Lexus SC400. Service 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
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
INSPECTION OF EGR VALVE
(Exc. USA Spec.)
1.
DRAIN ENGINE COOLANT (See page
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
–
EMISSION CONTROL SYSTEMS
Exhaust Gas Recirculation (EGR) System
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