Idle Control System

Idle Control System
When the engine is cold, the A/C compressor is on, the transmission is in gear, the brake pedal is depressed the P/S load is high, or the alternator is charging, the ECM controls current to the IAC valve to maintain the correct idle speed.




Idle Control System Diagram
The idle speed of the engine is controlled by the IAC (Idle Air Control) valve:
- After the engine starts, the IAC valve opens for a certain time. The amount of air is increased to raise the idle speed.
- When the engine coolant temperature is low, the IAC valve is opened to obtain the proper fast idle speed. The amount of bypassed air is thus controlled in relation to engine coolant temperature.