K 3500 Truck 4WD V8-454 7.4L (1994)
Idle Speed/Throttle Actuator - Mechanical: Description and Operation
Purpose:
The idle speed control actuator system assists the idle air control system in controlling the idle speed, primarily at cold temperatures.
Operation:
The idle speed control actuator is a vacuum operated device which opens the throttle slightly (2 to 3 degrees of angle) to increase the cold engine idle
speed, to improve the mixing of the air and fuel, and to allow lower warmed up engine idle speeds. The idle speed control actuator is controlled by the
idle speed control actuator solenoid, which is controlled by the control module. To increase the idle speed, the solenoid is turned "OFF," and no
vacuum is routed to the idle speed control actuator, allowing it to open the throttle slightly. To decrease the idle speed, the solenoid is turned "ON"
and vacuum is routed through the solenoid to the idle speed control actuator, allowing the throttle to fully close.
In conjunction with the idle speed control actuator system, the idle air control continuously monitors and controls the engine idle speed to the desired
idle speed. A Tech 1 scan tool will read the control module commands to the idle speed control actuator system.
