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.