Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: ACIS Control Circuit
DESCRIPTION
ACIS (Acoustic Control Induction System) controls the opening and closing the intake air control valve sub-assembly built into the intake air surge tank assembly to increase the intake efficiency according to the engine load.
When the engine speed is between 0 and 4300 rpm and the throttle valve opening angle is 30° or more, the ECM activates the No. 1 vacuum switching valve (for intake air control valve sub-assembly) which then applies vacuum from the vacuum pump assembly to the diaphragm actuator sub-assembly and closes the intake air control valve sub-assembly.
When the engine speed and/or throttle valve opening angle are not as specified above, the ECM deactivates the No. 1 vacuum switching valve (for intake air control valve sub-assembly), causing the intake air control valve sub-assembly to open.
WIRING DIAGRAM
CAUTION / NOTICE / HINT
NOTICE:
Inspect the fuses for circuits related to this system before performing the following procedure.
PROCEDURE
| 1. | PERFORM ACTIVE TEST USING TECHSTREAM (ACTIVATE THE VSV FOR INTAKE CONTROL) |
(a) Connect the Techstream to the DLC3.
(b) Start the engine.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine / Active Test / Activate the VSV for Intake Control.
Powertrain > Engine > Active Test| Tester Display |
|---|
| Activate the VSV for Intake Control |
(e) According to the display on the Techstream, perform the Active Test to operate the No. 1 vacuum switching valve (for intake air control valve sub-assembly) and check for the operating sound of the intake air control valve sub-assembly in the intake air surge tank assembly.
OK:
Operating sounds can be heard.
| OK | .gif) | PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE |
|
.gif)
| 2. | INSPECT INTAKE AIR SURGE TANK ASSEMBLY (INTAKE AIR CONTROL VALVE SUB-ASSEMBLY OPERATION) |
(a) Inspect the intake air surge tank assembly (intake air control valve sub-assembly).
Click here .gif)
| NG | | REPLACE INTAKE AIR SURGE TANK ASSEMBLY |
|
| 3. | INSPECT VACUUM HOSE SUB-ASSEMBLY (NO. 1 VACUUM SWITCHING VALVE (FOR INTAKE AIR CONTROL VALVE SUB-ASSEMBLY) - INTAKE AIR SURGE TANK ASSEMBLY) |
(a) Check the vacuum hose sub-assembly (No. 1 vacuum switching valve (for intake air control valve sub-assembly) - intake air surge tank assembly) for looseness, disconnection and blockage.
OK:
No looseness, disconnection or blockage.
| NG | | REPAIR OR REPLACE VACUUM HOSE SUB-ASSEMBLY |
|
| 4. | CHECK VACUUM |
| (a) Disconnect the vacuum hose sub-assembly from the No. 1 vacuum switching valve (for intake air control valve sub-assembly). |
|
(b) Start the engine.
(c) Using your finger, confirm that the hose has suction.
| Result | Proceed to |
|---|---|
| Suction applied | A |
| No suction | B |
| B | | GO TO STEP 9 |
|
| 5. | INSPECT NO. 1 VACUUM SWITCHING VALVE (FOR INTAKE AIR CONTROL VALVE SUB-ASSEMBLY) |
(a) Inspect the No. 1 vacuum switching valve (for intake air control valve sub-assembly).
Click here
| NG | | REPLACE NO. 1 VACUUM SWITCHING VALVE (FOR INTAKE AIR CONTROL VALVE SUB-ASSEMBLY) |
|
| 6. | CHECK TERMINAL VOLTAGE (POWER SOURCE OF NO. 1 VACUUM SWITCHING VALVE (FOR INTAKE AIR CONTROL VALVE SUB-ASSEMBLY)) |
| (a) Disconnect the No. 1 vacuum switching valve (for intake air control valve sub-assembly) connector. |
|
(b) Turn the engine switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| D11-2 - Body ground | Engine switch on (IG) | 11 to 14 V |
| NG | | GO TO STEP 8 |
|
| 7. | CHECK HARNESS AND CONNECTOR (NO. 1 VACUUM SWITCHING VALVE (FOR INTAKE AIR CONTROL VALVE SUB-ASSEMBLY) - ECM) |
(a) Disconnect the No. 1 vacuum switching valve (for intake air control valve sub-assembly) connector.
(b) Disconnect the ECM connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| D11-1 - D2-66 (ACIS) | Always | Below 1 Ω |
| D11-1 or D2-66 (ACIS) - Body ground and other terminals | Always | 10 kΩ or higher |
| OK | | REPLACE ECM |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
| 8. | CHECK HARNESS AND CONNECTOR (SEMICONDUCTOR PWR INTEGRATION ECU - NO. 1 VACUUM SWITCHING VALVE (FOR INTAKE AIR CONTROL VALVE SUB-ASSEMBLY)) |
(a) Disconnect the semiconductor pwr integration ECU connector.
(b) Disconnect the No. 1 vacuum switching valve (for intake air control valve sub-assembly) connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| 1G-1 - D11-2 | Always | Below 1 Ω |
| 1G-1 or D11-2 - Body ground and other terminals | Always | 10 kΩ or higher |
| OK | | GO TO ECM POWER SOURCE CIRCUIT |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
| 9. | INSPECT VACUUM PUMP ASSEMBLY |
(a) Inspect the vacuum pump assembly.
Click here
| OK | | REPAIR OR REPLACE VACUUM HOSE SUB-ASSEMBLY (NO. 1 VACUUM SWITCHING VALVE (FOR INTAKE AIR CONTROL VALVE SUB-ASSEMBLY) - VACUUM PUMP ASSEMBLY) |
| NG | | REPLACE VACUUM PUMP ASSEMBLY |
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Lexus RX (RX 350L, RX450h) 2016-{YEAR} Owners Manual
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Lexus RX (RX 350L, RX450h) 2016-{YEAR} Repair Manual
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