Lexus SC300 / Lexus SC400. Manual - part 716

4. INSPECT 

VSV

A.

Inspect VSV for open circuit
Using an ohmmeter, check that there is continuity between
the terminals.

Resistance (Cold): 30–34 

If there is no continuity, replace the VSV.

B.  Inspect VSV for ground

Using an ohmmeter, check that there is no continuity be-
tween each terminal and the body.
If there is continuity, replace the VSV.

C.  Inspect VSV operation

(a)  Check that the air flows with difficulty from ports E to F.

(b)  Apply battery voltage across the terminals.
(c)  Check that the air flows without resistance from port E

to F.

If operation is not as specified, replace the VSV.

5. REINSTALL 

VSV

(a)  Install the VSV with the two bolts.
(b)  Connect the two wire clamps to the VSV bracket.

EC–12

–

EMISSION CONTROL SYSTEMS

Fuel Evaporative Emission Control (EVAP) System

(c)  Connect the following hoses:

(1)  Vacuum hose (from vacuum pipe) to VSV
(2)  Vacuum hose (from charcoal canister) to VSV

(d)  Connect the VSV connector.

6. 

REINSTALL 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 (from ISC valve) to intake air connector
(2) Air 

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

nector

7. RECONNECT 

CABLE 

TO 

NEGATIVE 

TERMINAL 

OF

BATTERY

INSPECTION OF CHECK VALVE

1. 

REMOVE CHECK VALVE
(a)  Disconnect the grommet on the check valve from the

bracket.

(b)  Remove the check valve from the hose end on the

charcoal canister.

(c)  Remove the grommet from the check valve.

2. 

INSPECT CHECK VALVE
(a)  Check that air flows from the yellow port to the black

port.

(b)  Check that air does not flow from the black port to the

yellow port.

If operation is not as specified, replace the check valve.

–

EMISSION CONTROL SYSTEMS

Fuel Evaporative Emission Control (EVAP) System

EC–13

3. REINSTALL 

CHECK 

VALVE

HINT: Reinstall the check valve with the black port facing the
charcoal canister side.
(a)  Install the grommet to the check valve.
(b)  Install the check valve to the hose end on the charcoal

canister.

(c)  Install the grommet on the check valve to the bracket.

EC–14

–

EMISSION CONTROL SYSTEMS

Fuel Evaporative Emission Control (EVAP) System

EXHAUST GAS RECIRCULATION (EGR) SYSTEM

DESCRIPTION

To reduce NOx emission, part of the exhaust gases are recirculated through the EGR valve to the intake 

manifold to lower the maximum combustion temperature.

OPERATION

Coolant Temp.

Condition

EGR Valve

Exhaust Gas

Below 53

°

C (127

°

F)

–

CLOSED

Not recirculated

Above 55

°

C (131

°

F)

(a)

Idling, Deceleration, Neutral, 
Low air volume, High Engine speed

CLOSED

Not recirculated

Above 55 C (131 F)

Except (a)

OPEN

*Recirculated

* The ECU calculates the appropriate number of steps according to the intake air volume and the engine speed, then
drives the stepping motor to maintain the EGR volume at a level appropriate to the driving conditions.

 

–

EMISSION CONTROL SYSTEMS

Exhaust Gas Recirculation (EGR) System

EC–15