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Test Description

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. Continue with test even if engine will not idle. If idle is too low, "SCAN" will display 80 or more counts or steps. If idle is high, "SCAN" will display zero counts (steps). Occasionally an erratic or unstable idle may occur. Engine speed may vary 200 RPM or more up and down. Disconnect IAC. If condition is unchanged, IAC is not at fault. There is a system problem. Proceed to step 3).
  2. When engine was stopped, IAC valve retracted (more air) to fixed park position to provide increased airflow during next engine start. "SCAN" will display 100 or more counts.
  3. IAC MUST be disconnected before performing this step. Test light will confirm ECM signals by a steady or flashing light on all circuits.
  4. There is a remote possibility that one of the circuits is shorted to voltage that would have been indicated by a steady light. Disconnect ECM and turn ignition on. Probe terminals to check for this condition.
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