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Home >> Lexus >> 1999 >> ES 300 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Idle Air Control (IAC) System >> Air Assist System
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Air Assist System

  1. Ensure engine is at normal operating temperature. Ensure idle speed is 650-750 RPM. Ensure transmission is in Neutral. Turn A/C off. Connect Jumper Wire (09843-18020) between terminals TE1 and E1 of DLC No. 1. See Figure.
  2. Engine speed should increase to about 900-1300 RPM for about 10 seconds then return to idle (650-750 RPM). Turn ignition off. Disconnect air assist hose from air pipe. See Fig 1. Plug hose end, and cap off hose pipe fitting.
  3. Start engine. If engine idles at about 500 RPM or less (or if engine stalls), air assist system is okay. If engine speed does not operate as specified, check and repair vacuum leak.
Fig 1: Locating Air Assist Hose
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