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 Actuator (ISA)
The ISA motor, located on the throttle body, is an electrically-driven actuator that changes the throttle stop angle by acting as a movable idle stop. The ECU commands the ISA to control engine idle speed and maintain a smooth idle during sudden engine deceleration. It does this by providing the appropriate voltage outputs to produce the idle speed or throttle stop angle required for the particular engine operating condition. There is no idle speed adjustment.
For cold engine starting, the throttle is held open for a longer period to provide adequate engine warm-up prior to normal operation. When starting a hot engine, the throttle is open for shorter time.
Under normal engine operating conditions, engine idle is maintained at a pre-programmed RPM, which may vary slightly due to engine operating conditions. Under certain engine deceleration conditions, the throttle is held slightly open.
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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.