Lexus ES300 (1997 year). Manual - part 525

SF064–02

S04582

S04595

Throttle
Stop Screw

Vacuum

No Clearance

Throttle Lever

S04594

VTA
E2

VC

Ohmmeter

Vacuum

SF–34

–

SFI

THROTTLE BODY

885

1997 LEXUS ES300   (RM511U)

INSPECTION

1.

CLEAN THROTTLE BODY

(a)

Using a soft brush and carburetor cleaner, clean the cast
parts.

(b)

Using compressed air, clean all the passages and aper-
tures.

NOTICE:
To prevent deterioration, do not clean the throttle position
sensor and IAC valve.

2.

INSPECT THROTTLE VALVE

(a)

Apply vacuum to the throttle opener.

(b)

Check that there is no clearance between the throttle stop
screw and throttle lever when the throttle valve is fully
closed.

3.

INSPECT THROTTLE POSITION SENSOR

(a)

Apply vacuum to the throttle opener.

(b)

Using an ohmmeter, measure the resistance between
each terminal.

Throttle valve 

condition

Between 

terminals

Resistance

Fully closed

VTA – E2

0.2 – 5.7 k

Ω

Fully open

VTA – E2

2.0 – 10.2 k

Ω

–

VC – E2

2.5 – 5.9 k

Ω

SF065–01

–

SFI

THROTTLE BODY

SF–35

886

1997 LEXUS ES300   (RM511U)

INSTALLATION

Installation is in the reverse order of removal (See page 

SF–33

).

S04529

DLC1

E1

TE1

DLC1

SST

S04533

RSC

+B

RSO

Ohmmeter

SF066–01

S04529

E1

DLC1

TE1

DLC1

SST

SF–36

–

SFI

IDLE AIR CONTROL (IAC) VALVE

887

1997 LEXUS ES300   (RM511U)

IDLE AIR CONTROL (IAC) VALVE

ON–VEHICLE INSPECTION

1.

INSPECT IAC VALVE OPERATION

(a)

Initial conditions:

Engine at normal operating temperature

Idle speed checked correctly

Transmission in neutral position

A/C switch OFF

(b)

Using SST, connect terminals TE1 and E1 of the DLC1.
SST

09843–18020

(c)

After engine speed is kept at approx. 1,000 rpm for 5 se-
conds, check that it returns to idle speed.

If the engine speed operation is not as specified, check the IAC
valve, wiring and ECM.
(d)

Remove the SST from the DLC1.
SST

09843–18020

2.

INSPECT IAC VALVE RESISTANCE

NOTICE:
”Cold” and ”Hot” in the following sentences express the
temperature of the coils themselves. ”Cold” is from –10

°

C

(14

°

F) to 50

°

C (122

°

F) and ”Hot” is from 50

°

C (122

°

F) to

100

°

C (212

°

F).

(a)

Disconnect the IAC valve connector.

(b)

Using an ohmmeter, measure the resistance between ter-
minal +B and other terminals (RSC, RSO).
Resistance:
Cold: 17.0 – 24.5 

Ω

Hot:   21.5 – 28.5 

Ω

If resistance is not as specified, replace the IAC valve.
(c)

Reconnect the IAC valve connector.

3.

INSPECT AIR ASSIST SYSTEM

(a)

Initial conditions:

Engine at normal operating temperature

Idle speed checked correctly

Transmission in neutral position

A/C switch OFF

(b)

Using SST, connect terminals TE1 and E1 of the DLC1.
SST

09843–18020

(c)

After engine speed is kept at 900 – 1,300 rpm for 10 se-
conds, check that it returns to idle speed.

S05510

Plug

Disconnect

Plug

–

SFI

IDLE AIR CONTROL (IAC) VALVE

SF–37

888

1997 LEXUS ES300   (RM511U)

(d)

Stop the engine.

(e)

Disconnect the air assist hose from the air pipe, and block
off the IAC valve exit and the entry to the pipe.

(f)

Start the engine and check that the idle speed reaches
500 rpm or below (the engine may stall).
If the idle does not reach 500 rpm or below, check for a
leak between the air assist hoses, pipe and injectors.

(g)

Remove the SST from the DLC1.
SST

09843–18020

(h)

Reconnect the air assist hose to the IAC valve.