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DTC P0505: Idle Control System Malfunction

  1. Start engine and run at 3000 RPM, with no loads and transmission in Park or Neutral, until radiator fan comes on. Allow engine to idle. Using scan tool, check idle speed data under no-load conditions (all accessories off). See IDLE SPEED SPECIFICATIONS table. If idle speed is within specification, problem is intermittent, system is okay at this time. If idle speed is less than minimum specification, go to next step. If idle speed is more than maximum specification, go to step  3.
    IDLE SPEED SPECIFICATIONS

    Application RPM
    3.2TL 630-730
  2. Disconnect IAC valve 3-pin connector. If engine speed drops or engine stalls, adjust base idle speed. If base idle speed cannot be adjusted, clean ports in throttle body. If engine speed does not drop, replace IAC valve.
  3. Turn ignition off. Remove air intake duct from throttle body. Start and idle engine. Place fingers on lower port in throttle body. If engine speed drops, adjust idle speed. If idle speed cannot be adjusted, replace IAC valve. If engine speed does not drop, check for vacuum leaks and ensure throttle valve is fully closed.
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