Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Idle Speed Control
Idle Air Control (IAC) valve controls engine idle speed by regulating flow of air to engine when throttle plates and CTP switch are closed. IAC valve is mounted on throttle valve housing.
IAC valve is operated by a cycled DC (duty cycle) voltage. PCM supplies cycled voltage to IAC switch to regulate engine idle speed with a warm engine between 650 and 750 RPM. The duty cycle will vary depending on engine load and engine conditions. Since the idle system is adaptive, no adjustments are necessary.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.