Dynasty L4-153 2.5L SOHC VIN K TBI (1992)
Speed Control Servo: Description and Operation
This electro-mechanical device contains three solenoid valves that control vacuum in the diaphragm chamber, pulling the cable and thereby the throttle.
The individual solenoid functions are:
Vacuum valve: When energized, this valve allows vacuum into the diaphragm chamber. When not energized, the valve is spring-loaded to
prevent vacuum from entering the diaphragm chamber.
Vent valve: When energized, this valve prevents vacuum from bleeding off, thereby allowing speed control function. When not energized, the
valve is spring-loaded to bleed off vacuum.
Safety valve: This valve functions like the vent valve, but its vacuum bleed is greater.
Power for all the solenoids is supplied through the ON/OFF and brake switches with one wire. Both the vacuum and vent solenoids are grounded by the
engine controller to operate speed control. The safety valve is always grounded.
