Resistance of IAC
OPERATION
The Idle Air Control (IAC) valve adjusts the engine idle speed. The valve is located on the side of the throttle body. The valve is controlled by a duty cycle signal from the PCM and allows air to bypass the throttle plate in order to maintain the proper idle speed.
Do not attempt to clean the IAC valve. Carburetor tune-up cleaners or any type of solvent cleaners will damage the internal components of the valve.
Fig. Fig. 1: The IAC can be monitored with an appropriate and Data-stream capable scan tool
REMOVAL & INSTALLATION
Fig. Fig. 2: IAC solenoid location-4.6L engine
TESTING
Conclusive testing of this component requires the use of special, factory-supplied equipment and is not included here. The tests below will provide valuable information regarding condition of the IAC motor and require only a VOM.
Fig. IAC motor assembly
Fig. IAC motor electrical connector pinouts
Fig. IAC motor and driver circuits
REMOVAL & INSTALLATION
The IAC motor is located on the rear of the throttle body secured by two Torx® screws.
Fig. IAC motor mounting screws (arrows)
Operation
The Idle Air Control (IAC) valve controls the amount of air that bypasses the throttle valve, which controls the engine idle speed. The IAC valve consists of windings, an armature, a return spring, and a rotary slide. The engine control module (ECM) pulses the voltage to the winding, the opposing forces on the armature by the return spring cause it to maintain a fixed position, adjusting the amount of bypass air to maintain the correct idle speed.
Removal & Installation
Testing
Checking Idle Air Control Valve (IAC) Triggering
Fig. IAC Connector
Fig. Showing the IAC Valve
WARNING
Do NOT check for ease of movement by prying on the rotary slide with a screwdriver or other tools that could cause scratching or other damage.
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