Chart C-2C, Idle Air Control Valve (IACV) Circuit Check: Notes

NOTE: Test numbers refer to test steps in diagnostic chart.

The ECM controls the IACV by sending voltage pulse to the correct servo winding to move motor shaft and valve pintle in or out. ECM voltage pulses are called counts. To increase idle speed, ECM retracts the IACV to allow more air to by-pass the throttle plate. To decrease idle speed, ECM extends the IACV to decrease by-pass air.