Idle Air Control (IAC) Valve

1995 Toyota T100 DX, RWD, StandardSECTION Idle Air Control (IAC) Valve
  1. Warm engine to normal operating temperature. Ensure idle speed is correct. See IDLE SPEED & MIXTURE in ADJUSTMENTS - 2.7L article.
  2. 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 RPM.
    NOTE: Data link connector No. 1 is located in engine compartment.
  3. Engine RPM should increase to specified RPM for 5 seconds, and then return to idle. See IAC VALVE ENGINE SPEED TESTING SPECIFICATIONS  table.
    IAC VALVE ENGINE SPEED TESTING SPECIFICATIONS

    Application Engine RPM
    2.7L 1000-1500
  4. 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.
  5. 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+ or +B and each remaining terminal. See Fig 2.
  6. Replace IAC valve if resistance is not within specification. See IAC VALVE RESISTANCE SPECIFICATIONS  table.
  7. To check IAC valve operation, remove IAC valve from throttle body. Connect battery voltage and ground to proper terminals and ensure valve opens and closes. See Fig 3. Replace IAC valve if defective.
  8. 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 wiring diagram in the WIRING DIAGRAMS article.
IAC VALVE RESISTANCE SPECIFICATIONS

Application Ohms
2.7L (1) 19.3-22.3
(1) Specification listed at 68°F (20°C).
Fig 1: Installing Jumper Wire In Data Link Connector No. 1
G95I33702Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.