Idle Air Control (IAC) Valve: Non-Turbo

Warm engine to normal operating temperature. Ensure idle speed is correct. See ADJUSTMENTS article.
Apply parking brake and place transmission/transaxle in Neutral. Install Jumper Wire (SST 09843-18020) between terminals TE1 and E1 of data link connector No. 1. See Fig 1. Start engine and note engine RPM.
NOTE: Data link connector No. 1 is located in engine compartment on all models except Previa. On Previa, data link connector No. 1 is located under below driver's seat.
On Previa, engine RPM should increase to specified engine RPM for 5 seconds and then decrease approximately 200 RPM. Refer to the IAC VALVE ENGINE SPEED TESTING SPECIFICATIONS table.

On all other models, engine RPM should increase to specified engine RPM for 5 seconds, and then return to idle. See the IAC VALVE ENGINE SPEED TESTING SPECIFICATIONS table.

IAC VALVE ENGINE SPEED TESTING SPECIFICATIONS

Application	Engine RPM
MR2	900-1300

On all models, if engine RPM is not as specified, check IAC valve resistance and operation. If engine RPM is within specification, remove jumper wire. Turn ignition off.
To check IAC valve resistance, ensure ignition is off. Disconnect electrical connector from IAC valve located on lower area of throttle body. Using ohmmeter, measure resistance between terminal B+ and each remaining terminal. See Fig 2 and Fig 3.
Replace IAC valve if resistance is not within specification. See IAC VALVE RESISTANCE SPECIFICATIONS (EXCEPT CAMRY 3.0L, LAND CRUISER & SUPRA) table.
NOTE: Information is not available from manufacturer for checking IAC valve operation for Previa.
To check IAC valve operation, remove IAC valve from throttle body. See N - REMOVE/INSTALL/OHAUL article. Connect battery voltage and ground to proper terminals and ensure valve opens and closes. See Fig 4 and Fig 5. Replace IAC valve if defective.

If IAC valve resistance is correct and operates correctly, check wiring circuit between Engine Control Module (ECM) and IAC valve. See ECM LOCATION table. See appropriate wiring diagram in WIRING DIAGRAMS article.

IAC VALVE RESISTANCE SPECIFICATIONS

Application	Ohms
Non-Turbo	19.3-22.3
Turbo	17.7-23.9

ECM LOCATION

Model	Location
MR2	Left Rear Of Engine Compartment

Fig 1: Installing Jumper Wire In Data Link Connector No. 1

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 2: Checking IAC Valve Resistance (Non-Turbo)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 3: Checking IAC Valve Resistance (Turbo)

Fig 4: Checking IAC Valve Operation (Non-Turbo)

Fig 5: Checking IAC Valve Operation (Turbo)

Warm engine to normal operating temperature. Ensure idle speed is correct. See ADJUSTMENTS article. Apply parking brake and place transaxle in Neutral.
With engine idling, disconnect electrical connector from IAC valve located on lower area of throttle body. Engine RPM should increase to at least 1000 RPM. Reinstall electrical connector on IAC valve.
Ensure engine returns to idle speed of 750-850 RPM. If engine does not return to proper idle speed, check IAC valve resistance and operation.
To check IAC valve resistance, ensure ignition is off. Disconnect electrical connector from IAC valve. Using ohmmeter, measure resistance between terminal B+ and each remaining terminal. See Fig 2 and Fig 3.
Replace IAC valve if resistance is not within specification. See IAC VALVE RESISTANCE SPECIFICATIONS (EXCEPT CAMRY 3.0L, LAND CRUISER & SUPRA) table.
To check IAC valve operation, remove IAC valve from throttle body. See N - REMOVE/INSTALL/OHAUL article. Connect battery voltage and ground to proper terminals and ensure valve opens and closes. See Fig 4 and Fig 5. Replace IAC valve if defective.
If IAC valve resistance is correct and operates correctly, check wiring circuit between Engine Control Module (ECM) and IAC valve. See ECM LOCATION table. See appropriate wiring diagram in WIRING DIAGRAMS article.