At idle, engine speed can be increased by retracting the IAC motor pintle and allowing more air to pass through the port, or it can be decreased by restricting the passage with the pintle and diminishing the amount of air bypassing the throttle plate.
The IAC motor has 4 wires with 4 circuits. Two of the wires are for 12 volts and ground to supply electrical current to the motor windings to operate the stepper motor in one direction. The other 2 wires are also for 12 volts and ground to supply electrical current to operate the stepper motor in the opposite direction.
A (factory adjusted) set screw is used to mechanically limit the position of the throttle body throttle plate. Never attempt to adjust the engine idle speed using this screw. All idle speed functions are controlled by the IAC motor through the ECM.
Removal & Installation
- Remove air resonator box at throttle body.
- Disconnect electrical connector from IAC motor.
- Remove two mounting bolts (screws).
Remove IAC motor from throttle body.
- Install IAC motor to throttle body.
- Install and tighten two mounting bolts (screws) to 60 inch lbs. (7 Nm).
- Install electrical connector.
- Install air resonator to throttle body.
- Turn the ignition off.
- Disconnect the IAC motor harness connector.
- Remove the IAC motor.
- Inspect the IAC air passages for restrictions and damage to the IAC motor.
- Measure the resistance across the IAC motor pin terminals.
- The resistance should be 8.7-10.7 ohms. If not, replace the motor.