2002 Toyota PriusFACTORY OEM SERVICE PROCEDURE

Idle Air Control Valve: Highlander

  1. If problem exists in Idle Air Control (IAC) valve or wiring circuit, a Diagnostic Trouble Code (DTC) P0505 may be stored in Engine Control Module (ECM). See TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article for retrieving of DTCs.
  2. To test IAC valve operation, remove IAC valve from throttle body. See THROTTLE BODY under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article. Reinstall electrical connector on IAC valve.
  3. Turn ignition on. Check that valve on inside of IAC valve moves from half open to fully closed, fully open and then returns to half open within .5 seconds. See Fig 1. Turn ignition off. If IAC valve operates as specified, wiring circuit, Engine Control Module (ECM) and IAC valve are okay.
  4. If IAC valve operates as specified, wiring circuit, Engine Control Module (ECM) and IAC valve are okay. Clear any stored DTCs from ECM after checking IAC valve operation. See CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. If IAC valve does not operate, check wiring circuit between ECM and IAC valve. ECM is located behind glove box. For illustration of ECM location, see THEORY & OPERATION article. See WIRING DIAGRAMS article. If wiring circuit and ECM are okay, replace IAC valve.
    Fig 1: Testing Idle Air Control Valve Operation (Highlander & RAV4)
    G00025339Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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