1997 Toyota Avalon XLSFACTORY OEM SERVICE PROCEDURE

Idle Air Control (IAC) Valve

  1. Start and warm engine to normal operating temperature. Ensure idle speed is within specification. See IDLE SPEED & MIXTURE in ADJUSTMENTS article.
  2. Shut engine off. Apply parking brake and place transmission/transaxle in Neutral. Ensure A/C is off. Install Jumper Wire (SST 09843-18020) between terminals TE1 and E1 on data link connector No. 1 located in the engine compartment. See Fig 1. Start engine and note engine RPM.
  3. Engine RPM should increase to 1000 RPM for 5 seconds and then return to idle. If engine RPM is not within specification, test IAC valve resistance and IAC valve operation. If engine RPM is within specification, remove jumper wire. Turn ignition off.
  4. To test IAC valve resistance, ensure ignition is off. Disconnect electrical connector from IAC valve. IAC valve is located on lower area of throttle body. Using ohmmeter, checking resistance between +B terminal and each remaining terminal on IAC valve. See Fig 2.
  5. Replace IAC valve if resistance is not within specification. See IAC VALVE RESISTANCE  table.
    IAC VALVE RESISTANCE

    Application Ohms
    Cold (1) 17.0-24.5
    Hot (2) 21.5-28.5
    (1) Cold is with temperature of 14-122°F (-10-50°C).
    (2) Hot is with temperature of 122-212°F (50-100°C).
  6. To test IAC valve operation, remove IAC valve from throttle body. Apply battery voltage to +B terminal on IAC valve. Apply battery ground to proper terminal and ensure valve opens and closes. See Fig 3. Replace IAC valve if defective.
  7. If IAC valve resistance is within specification 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.
ECM LOCATION

Model Location
Avalon Behind Glove Box
Fig 1: Installing Jumper Wire Between Data Link Connector No. 1 Terminals
G97A28878Courtesy 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.

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