Chart C-2C - Idle Air Control Valve 3.1L Pickup: Notes

NOTE: Test numbers refer to numbers on diagnostic chart.

Continue with test, even if engine will not idle. If idle is too low, scan tester will display 80 or more counts. If idle is high, it will display zero counts. Occasionally, an erratic or unstable idle may occur. Engine speed may vary 200RPM or more up and down. Disconnect IAC valve. If condition is unchanged, IAC is not at fault.
When engine was stopped, IAC valve plunger retracted (more air) to a fixed park position for increased air flow and idle speed during next engine start. 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.
ensure IAC valve is disconnected before testing. Test light will confirm ECM signals with a steady or flashing light on all circuits.
A circuit may be shorted to voltage, which would be indicated by a steady light. Disconnect ECM, and turn ignition on. Probe terminals to check for this condition.