Idle Air Control (IAC) Valve
NOTE:
IAC valve may also be referred to as Idle Speed Control (ISC) valve.
ECM LOCATION
| Model | Location |
|---|---|
| Land Cruiser | Above Glove Box |
- Listen for clicking sound at IAC valve immediately after engine is shut off.NOTE: IAC valve is located on throttle body.
- If no clicking sound is heard, check IAC valve resistance and operation. To check IAC valve resistance, ensure ignition is off. Disconnect electrical connector from IAC valve. Note IAC valve terminals. See Fig 1.
- Using ohmmeter, measure resistance between specified terminals. See IAC VALVE RESISTANCE SPECIFICATIONS table. Replace IAC valve if resistance is not within specification.IAC VALVE RESISTANCE SPECIFICATIONS
Terminals Ohms B1 To S1 Or S3 10-30 B2 To S2 Or S4 10-30 - To check IAC valve operation, remove IAC valve. See N - REMOVE/INSTALL/OHAUL article. Note IAC valve terminal identification. See Fig 1.
- Apply battery voltage to terminals B1 and B2. See Fig 2 and Fig 3. Repeatedly ground terminals in sequence and ensure IAC valve closes and opens. See IAC VALVE GROUNDING SEQUENCE table. Replace IAC valve if defective.IAC VALVE GROUNDING SEQUENCE
Application Terminal Grounding Sequence To Close IAC Valve S1-S2-S3-S4-S1 To Open IAC Valve S4-S3-S2-S1-S4 - If IAC valve resistance is correct and operates correctly, check wiring between Engine Control Module (ECM) and IAC valve. See ECM LOCATION table. See appropriate wiring diagram in WIRING DIAGRAMS article.