Idle Control System (A/T Only)

Description
The Idle Control System (A/T only) system maintains a stable idle speed under different engine loads.
Idle control is accomplished using two throttle controllers, the idle boost throttle controller (with A/C, this controller has a dual diaphragm) and the throttle controller.
The solenoid valve [1][2]control unit monitors the inputs shown and directs voltage to the three solenoid valves:-

1. The Idle Boost Solenoid Valve is energized when the transmission is in gear or the coolant temperature is below 7O°C (158°F), applying vacuum to the idle boost throttle controller.

2. The A/C Idle Boost Solenoid Valve is energized when the A/C compressor is energized, applying vacuum to the outer diaphragm of the idle boost throttle controller.

3. The Frequency Solenoid Valve C is energized when the engine speed is above or below 73O rpm or the coolant temperature is above 6O°C (14O°F).