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Home >> Chevrolet >> 1989 >> Cavalier VL, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> 2.0L(K)/2.5L Tests W/Codes >> Description >> Chart C2C - Idle Air Control Check >> Notes
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Chart C2C - Idle Air Control Check: Notes

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. Continue with test, even if engine won't idle. If idle is too low, "Scan" tester will display 80 or more counts. If idle is high, it will display zero counts. Sometimes, an erratic or unstable idle may occur. Engine speed may vary 200 RPM or more up and down. Disconnect IAC. If condition is unchanged, the IAC is not at fault.
  2. When the engine was stopped, the IAC plunger retracted (more air) to a fixed "park" position for increased airflow and idle speed during the next engine start. A "Scan" tester will display 100 or more counts. When performing this test, immediately note RPM on start-up. On a warm engine, RPM will decrease rapidly.
  3. Be sure to disconnect the IAC valve prior to this test. Test light will confirm the ECM signals with a steady or flashing light on all circuits.
  4. There is a remote possibility that one of the circuits is shorted to voltage, which would have been indicated by a steady light. Disconnect ECM and turn the ignition on. Probe terminals to check for this condition.
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