Visually check the connector, making sure it is properly attached and all of the terminals are straight, tight and free of corrosion.
You need to have access to a DRB or equivalent scan tool to accurately test the Idle Air Control (IAC) motor and related circuits. Make sure to carefully follow all of the scan tool manufacturers directions when testing the IAC motor.
If you do not have access to a scan tool, this simple test should give you an indication if the circuit is working properly. First attach a tachometer to the engine, and then start the engine.
Observe the idle speed. Pull a vacuum hose (like the one leading from the brake booster to the intake manifold). The idle speed should rise, and then fall as the IAC motor tries to compensate for the vacuum leak.
Reattach the vacuum hose. The idle should drop, and then stabilize.
If the engine reacted as indicated, the circuit is probably OK.
Description & Operation
The Idle Air Control (IAC) motor, attached to the side of the throttle body, is operated by the PCM. The PCM adjusts engine idle speed through the idle air control motor to compensate for load on the engine, or ambient conditions.
The throttle body has an air bypass passage that provides air for the engine during closed throttle idle. The idle air control motor pintle protrudes into the air bypass passage and regulates the airflow through it. The PCM adjusts the idle speed by moving the IAC motor pintle in and out of the bypass passage. The speed is based on various sensor and switch inputs received by the PCM. The inputs are from the throttle position sensor, crankshaft position sensor, coolant temperature sensor, as well as various switch operations (brake, park/neutral, air conditioning). Increasing airflow when the throttle is closed quickly after a driving condition also prevents deceleration die out.
Removal & Installation
When servicing throttle body components, always reassemble components with new O-rings and seals where applicable. Never use lubricants on O-rings or seals as damage may result. If assembly of component is difficult, use water to aid assembly. Use care when removing hoses to prevent damage to hose or hose nipple.
- Disconnect negative cable from battery.
- Remove electrical connector from idle air control motor.
- Remove idle air control motor mounting screws.
- Remove motor from throttle body. Ensure the O-ring is removed with the motor.
The new idle air control motor has a new O-ring installed on it. If pintle measures more than 1 inch (25 mm) it must be retracted. Use the scan tool Idle Air Control Motor Open/Close test function to retract the pintle (battery must be connected.)
- Carefully place idle air control motor into throttle body.
- Install mounting screws. Tighten screws to 2 Nm (17 inch lbs.) torque.
- Connect electrical connector to idle air control motor.
Connect negative cable to battery.