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).
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