Idle Speed: Description and Operation

CIRCUIT DESCRIPTION
The Idle Speed Control (ISC) motor opens and closes the throttle valve according to signals from the Powertrain Control Module (PCM). The ISC motor will extend the plunger of the motor when the motor receives the correct signals from the PCM. Extending the plunger of the ISC motor opens the throttle plates and increases the idle speed. When a higher idle speed is no longer required, the PCM will reverse the polarity of the signals to the ISC motor. The change in the polarity of the signals reverses the direction of the ISC motor. The plunger of the ISC motor then retracts, causing the throttle plates to close and decrease the idle speed.