Basic Operation

Idle Speed Control System:

NOTE: The cruise control system is independent of the idle speed control and has a separate cruise control actuator and CC control module.

PURPOSE
The HFM-SFI control module (N3/4) controls idle speed to ensure smooth and consistent operation regardless of engine temperature and load.

OPERATION
When the ignition switch is in the ON position, idle speed control is in operation. The position of the throttle valve for the idle speed is determined by the control unit. The actual value potentiometer in the idle speed control (ISC) actuator signals the position of the throttle valve. The control module processes various input signals and specifies the position of the throttle valve via the output signal. This signal is used by the ISC actuator to adjust the throttle valve.

Before starting the engine, the throttle valve position is determined by the engine temperature. Once the engine is running, the idle speed is controlled by the control module (HFM-SFI) which provides a constant idle RPM, compensating for engine temperature and load.