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Home >> Lexus >> 1998 >> SC 400 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Idle Control System >> Idle Air Control (IAC) System (Es300) >> 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. Increase engine speed to about 900-1300 RPM for about 10 seconds. Release throttle. Engine speed should decrease to idle speed of 650-750 RPM. Stop engine. Disconnect air hose from air pipe. See Figure. Plug hose end, and cap off the 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 does not operate as specified, check and repair vacuum leak.
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