Lexus RX300 (MCU15). Service manual - part 221

A06092

1

3

5

2

4

6

IACV No.2

IACV No.1, No.2 closed (VSV: OFF)

Throttle Valve

30

°

3,700 rpm

Engine Speed

Throttle V

alve

Opening Angle

FI7011  FI6570

IACV No.1

2,700 rpm

IACV No.1 open (VSV: ON)
IACV No.2 closed (VSV: OFF)

IACV No.1, No.2 open (VSV: ON)

DI–116

–

DIAGNOSTICS

ENGINE

LEXUS RX300   (RM785E)

DTC

P1651

VSV for ACIS Circuit Malfunction (Bank 1)

DTC

P1666

VSV for ACIS Circuit Malfunction (Bank 2)

CIRCUIT DESCRIPTION

This circuit opens and closes the IACV (Intake Air Control Valve) in response to the engine load in order to
increase the intake efficiency (ACIS: Acoustic Control Induction System).
When the engine speed is 3,700 rpm or less and the throttle valve opening angle is 30

° or more, the engine

ECU turns the two VSV ON or OFF and operate the IACV.

DTC No.

DTC Detecting Condition

Trouble Area

P1651

P1666

Proper response to engine ECU command does not occur

(2 trip detection logic)

S Open or short in VSV circuit for ACIS

S VSV for ACIS

S Engine ECU

DI64K–03

A14521

Engine ECU

ACIS

17
E8

V1
VSV for ACIS (No.1)
B–R

R–Y

5

3

EFI

Battery

1

EFI Relay

Engine Room J/B

2

J2

A

ED

E7

E9

ACII

MREL

15

8

V2

VSV for ACIS (No.2)

B–R

B–R

LG

5

1

3

4

B–W

W–B

2D

2F

2B

2I

W

W

1

3

J/C

FL Block

F11

1

2

2

1

A00307

ON

VSV is ON

VSV is OFF

Air Filter

Air

Air

E

F

E

F

BE6653
FI7073 FI7074

–

DIAGNOSTICS

ENGINE

DI–117

LEXUS RX300   (RM785E)

WIRING DIAGRAM

INSPECTION PROCEDURE
Hand–held tester:

HINT:

S

Read freeze frame data using hand–held tester or OBD scan tool. Because freeze frame records the
engine conditions when the malfunction is detected. When troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine was warmed up or not, the air–fuel ratio was
lean or rich, etc. at the time of the malfunction.

S

If DTC P1651 displayed, check left bank VSV circuit.

S

If DTC P1666 displayed, check right bank VSV circuit.

1

Connect hand–held tester and check operation of VSV for ACIS.

PREPARATION:
(a)

Connect the hand–held tester to the DLC3.

(b)

Turn the ignition switch ON and push the hand–held tes-
ter main switch ON.

(c)

Select the ACTIVE TEST mode on the hand–held tester.

CHECK:
Check operation of the VSV when VSV is operated by the
hand–held tester.
OK:

VSV is ON:
Air from port E flows out through port F.
VSV is OFF:
Air from port E flows out through the air filter.

DI–118

–

DIAGNOSTICS

ENGINE

LEXUS RX300   (RM785E)

OK

Check for vacuum tank (See page FI–53).

NG

2

Check VSV for ACIS (See page FI–53).

NG

Replace VSV for ACIS.

OK

3

Check for open and short in harness and connector between EFI main relay and
(Marking: EFI) engine ECU (See page IN–32).

NG

Repair or replace harness or connector.

OK

Check and replace engine ECU 
(See page IN–32).

OBD scan tool (excluding hand–held tester):

1

Check VSV for ACIS (See page FI–53).

NG

Replace VSV for ACIS.

OK

A11824

ON

ACIS

(+)

(–)

ACI1

–

DIAGNOSTICS

ENGINE

DI–119

LEXUS RX300   (RM785E)

2

Check voltage between terminal ACIS of engine ECU connector and body
ground.

PREPARATION:
(a)

Remove the engine ECU with connector still connected
(See page FI–70).

(b)

Turn the ignition switch ON.

CHECK:
Measure the voltage between terminal ACIS , ACI1 of the en-
gine ECU connector and body ground.
OK:

Voltage: 9 – 14 V

NG

Check for open and short in harness and con-
nector between EFI main relay (Marking: EFI)
and engine ECU (See page IN–32).

OK

Check and replace engine ECU 
(See page IN–32).