Using an ohmmeter, measure the resistance at terminal 3.If voltage is ok, proceed to the next step. If voltage is not present or out of range, repair the circuit. Turn the ignition ON, and measure the voltage between terminal 1 and ground. Using an voltmeter, measure the voltage at terminal 1.Turn the ignition ON, and measure the voltage between terminal 2 and ground. Using an voltmeter, measure the voltage at terminal 2.Finally, if resistance is out of range, replace the idle air control valve (IAC) and retest. If resistance is ok, proceed to the next step. Using an ohmmeter, measure the resistance between pins 1 and 2 on the (IAC) valve. Finally, if resistance is out of range, replace the (IAC) and retest. Using an ohmmeter, measure the resistance between pins 3 and 2 on the (IAC) valve. How To test the coil driver circuits in the (IAC) valve: Because of this feature, the idle air control valve (IAC) valve is not adjustable.įirst, Disconnect the negative battery cable and unplug the (IAC) connector. The (ECM) incorporates a self-learning system, which enables it to learn the ideal idling speed. As a result, the idling speed is increased to approximately 1200 RPM. In the event of an electrical fault, a spring maintains the rotary valve in a fixed position. If the code P0505 appeared soon after the battery has been replaced or disconnected, it’s a good idea to try performing the idle relearn procedure. If the idle speed still surges after this, the (IAC) valve is defective and needs to be replaced.Consequently, until no white smoke, is coming out of the exhaust pipe. Start the engine and rev and hold to 1,500 to 2,000 rpm.Turn the engine off again, and reattach the air intake duct work to the throttle body.Restart the engine, rev and hold at 1,000 to 1,500 rpm, and repeat the cleaning process again.Turn the engine off, to allow the cleaner to soak into the (IAC) passageway.But, try aiming for, the idle air bypass port. Spray the throttle cleaner or engine cleaner into the throat of the throttle body.Start the engine, then increase and hold the idle speed to 1,000 to 1,500 rpm.Disconnect the air intake ductwork, from the throttle body.The cure for this condition is to clean the valve, with some aerosol throttle cleaner or engine top cleaner. One common problem is a buildup of carbon or fuel varnish deposits, in the idle speed control valve. How To Clean The Idle Air Control Valve (IAC): And, the steering wheel might also feel, like it’s being dragged to one side too. For example, if you turn on your heater or air conditioner, then your engine will probably stall immediately afterward. Sometimes the engine stalling will happen on its own while other times, increasing the load on the engine, will cause it to stall. And, in some cases, may result in an engine that will not idle at all. This may result in the engine stalling while operating. If the idle air control valve (IAC) fails completely, it may leave the vehicle, without a source of air. Engine StallingĪnother more serious symptom of an issue with the (IAC) is engine stalling. Since less air will be going into the engine during its idle state, the car will react by shaking profusely. A rough idle will result in, intense vibrations forming, whenever your vehicle is stopped with the engine running. But, if the valve goes bad for any reason, the idling will go from smooth to rough. Rough Engine IdleĪ normal healthy idle air control valve (IAC), will provide smooth idling in your vehicle. Therefore, having the computer scanned for trouble codes, is highly recommended. Check Engine Lightīut, the Check Engine Light, can also come on for a variety of other issues. As a result, of the engine control module detecting an issue with the idle air control valve circuit or signal. Check Engine Light IlluminatedĪnother symptom of a potential issue with the idle air control valve (IAC) is, an illuminated Check Engine Light. And, in some cases, a surging idle speed, that repeatedly climbs and falls. This may result in an unusually high or low idle speed. So, if the valve fails or has any issues, it can cause the idle speed to be thrown off. The (IAC) is programmed, to regulate and maintain the engine idle speed, at a constant rate. So, one of the most common symptoms associated with a problematic idle air control valve (IAC) is, irregular idle speed. Many can alert the driver of a potential issue: Irregular Idle Speed Usually, a bad or failing idle air control valve (IAC), will produce a few failure symptoms. And, in some cases, may even render it undrivable. So, when the idle air control valve (IAC) fails, it can cause all sorts of issues.
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