Idle Speed Control System

Idle Air Control (IACV) System Input/Output Chart:

PURPOSE
The Idle Air Control System allows for precise control of the engine idle during cold, warm and high load conditions.

LOCATION
The ECM is on the floor under the passenger's seat and all idle control valves are on the back of the intake manifold, near the firewall.

OPERATION
Idle speed is controlled by fine adjustment of the amount of air allowed to bypass the throttle valve.

Two devices, both part of the Idle Control System, are used to control engine idle. The devices are:

1. Idle Air Control Valve-Air Regulator (IACV-Air Reg)
^ Used to provide additional by-pass air during cold engine operation. Allows cold fast idle. Is activated by 12 VDC.
2. Idle Air Control Valve-Auxiliary Air Control (IACV-ACC) Valve.
^ Used to provide fine control of the engine idle during normal conditions. Is activated by a duty cycle signal from the ECM at a rate of 100 - 200 Hz.