Idle Air Control Valve Control: Overview

IDLE AIR CONTROL VALVE CONTROL - OVERVIEW





There are two reasons that the Engine Control Module (ECM) controls the Idle Air Control (IAC) Valve. To maintain a constant idling speed regardless of load and to regulate negative pressure to the engine.

The engine control module (ECM) computes the output signals to the idle air control (IAC) valve (7) using information from:

- Throttle Position (TP) Sensor (1)
- Engine Coolant Temperature (ECT) Sensor (2)
- Engine Speed (RPM) Sensor (3)
- Pressure Switch (Pressostat) (4)
- Combined Instrument Panel, speed signal (6).

Information from the transmission control module (TCM) (5) regarding gear selector position is also used.