Idle Speed/Throttle Actuator - Electronic: Testing and Inspection

Chart C-2A:

IAC Valve Circuit:

CIRCUIT DESCRIPTION:
When the engine control module receives a signal from the diode module, requesting idle-up, the Idle Air Control (IAC) valve is grounded. With the IAC valve grounded, a passage to air is opened to the intake manifold. With the increased air entering the intake manifold, the engine idle speed is increased. The idle will return to normal as soon as the need for increased idle no longer exists.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. This checks to see if the system is operating normally.
2. This checks for an open in the WHT/BLU wire.
3. This checks for a fault in the RED/WHT wire, a faulty ECM or for a faulty IAC valve.