Forester S F4-2.5L DOHC (1998)
Cruise Control Vacuum Solenoid: Description and Operation
VALVE OPERATIONS
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When the cruise control is out of operation, the safety valve and vent valve are opened and the vacuum valve is closed. Therefore, the inside of the
actuator is at atmospheric pressure, and the diaphragm does not operate.
During constant-speed driving with the main switch on, the safety valve closes, and the vacuum valve and vent valve open and close to introduce a
vacuum or air at atmospheric pressure into the actuator. This moves the diaphragm, which operates the throttle cam to provide control over the
vehicle speed.
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The vacuum valve introduces the vacuum while the current supply is ON, and blocks the vacuum when the current supply is interrupted.
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The vent valve shuts off the atmospheric air while the current supply is ON and retains the vacuum in the vacuum chamber. When the current
supply is interrupted, it introduces the atmospheric air.
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The safety valve blocks the atmospheric pressure while the current supply is ON, and introduces the atmospheric air when the current supply is
OFF
When cruise control is cancelled, or when the vehicle is decelerated, the vent valve is opened to simultaneously introduce the atmospheric air for
faster deceleration.
How the valves operate in response to signals from the control module
