Toyota Avalon (XX50) 2019-2022 Service & 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

(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.

(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

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

(a) Inspect the intake air surge tank assembly (intake air control valve sub-assembly).

Click here

NG

REPLACE INTAKE AIR SURGE TANK ASSEMBLY

OK

(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

OK

(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.

B

GO TO STEP 9

A

(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)

OK

(a) Disconnect the No. 1 vacuum switching valve (for intake air control valve sub-assembly) connector.

*a Front view of wire harness connector (to No. 1 Vacuum Switching Valve (for Intake Air Control Valve Sub-assembly))

(b) Turn the engine switch on (IG).

(c) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

NG

GO TO STEP 8

OK

(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:

OK

REPLACE ECM

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

(a) Remove the EFI-MAIN NO. 1 relay from the No. 1 engine room relay block and No. 1 junction block assembly.

(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:

OK

GO TO ECM POWER SOURCE CIRCUIT

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

(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