Intake Air Control Valve (IACV) System: 3.0L

Using a 3-way connector, connect vacuum gauge to actuator valve. See Fig 1. Start engine. With engine idling, ensure no vacuum reading is obtained.
Fully open throttle, and ensure vacuum reading momentarily reads approximately 8 in. Hg and actuator valve rod pulls inward. If actuator valve rod does not pull inward, proceed to step 3).

Fig 1: Checking Actuator Valve Operation (3.0L)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Disconnect vacuum hose from actuator valve. Using vacuum pump, apply approximately 8 in. Hg of vacuum to actuator valve. Ensure actuator valve rod pulls inward and remains pulled inward for at least one minute. Replace actuator valve if defective. If actuator valve operates correctly, reconnect vacuum hose and proceed to step 4).
Disconnect vacuum hoses from vacuum tank, located near driver's side headlight in engine compartment. Apply air pressure to port "B" on vacuum tank and ensure air passes out port "A". See Fig 2. Apply air pressure to port "A" and ensure air does not pass out port "B". See Fig 2.
Plug port "B" on vacuum tank. Using vacuum pump, apply approximately 8 in. Hg of vacuum to port "A". See Fig 2. Ensure vacuum reading will hold for at least one minute. Replace vacuum tank if defective and recheck system operation. If vacuum tank is okay, reconnect vacuum hoses and proceed to step 6).

Fig 2: Checking Vacuum Tank (3.0L)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Disconnect electrical connectors from IACV Vacuum Switching Valve (VSV), located near valve cover. See Fig 3. Using ohmmeter, ensure continuity exists between electrical terminals on VSV. Check that no continuity exists between each electrical terminal and the body of the VSV.
Apply air pressure to port "B" and ensure air passes out the filter. See Fig 4. Connect battery voltage to VSV terminals. Apply air pressure to port "B" and ensure air passes out port "A". See Fig 4. Replace VSV if defective and recheck system operation. If VSV is okay, proceed to step 8).
Turn ignition on. Check for battery voltage at Black/Orange wire of VSV electrical connector. If battery voltage exists, replace Electronic Control Unit (ECU). If battery voltage does not exist, check EFI main relay. See EFI MAIN RELAY under RELAYS.
If EFI main relay is okay, check wiring. See appropriate wiring diagram in WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section. Repair as necessary and recheck system operation.

Fig 3: Locating IACV Vacuum Switching Valve (3.0L)

Fig 4: Checking IACV Vacuum Switching Valve