OBD II scan tool (excluding hand-held tester):

Check VSV for ACIS (See INSPECTION ).
NG: Replace VSV for ACIS (See VSV FOR ACOUSTIC CONTROL INDUCTION SYSTEM (ACIS) ).

OK: Go to next step.
Check voltage between terminal ACIS of ECM connector and body ground.
PREPARATION:
1. Remove the ECM hood (see ENGINE CONTROL MODULE (ECM) ).
2. Turn the ignition switch ON.
CHECK:

Measure the voltage between terminal ACIS of the ECM connector and body ground.

Fig 1: Identifying Terminal ACIS Of ECM Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK:
1. Voltage: 9 to 14 V
NG: Go to step 4 .

OK: Go to next step.
Check for open and short in harness and connector between EFI main relay (Marking: EFI) and ECM (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ).
NG: Repair or replace harness or connector.

OK: Go to next step.
Check vacuum hose.
CHECK:
1. Check that the vacuum hoses are connected correctly.
2. Check that the vacuum hoses are not loose or disconnected.
3. Check the vacuum hoses for cracks, holes or damage.
NG: Repair or replace vacuum hose.

OK: Go to next step.
Check intake air control valve (See ACOUSTIC CONTROL INDUCTION SYSTEM (ACIS) ).
NG: Replace intake air control valve (See REMOVAL ).

OK: Replace ECM (See ENGINE CONTROL MODULE (ECM) ).