240 L4-2.3L SOHC VIN 88 B230F (1986)
Cruise Control Switch: Description and Operation
Cruise control 1986 on
In 1986, a new cruise control system was introduced which is used in conjunction with the electronic speedometer. The control module stores the
exact speed of the vehicle at the moment that the set button is pressed and released. This system adjusts the throttle position eight times per second to
hold the speed within a ±1 mph range as long as the car is capable of achieving the speed selected.
The system uses a vacuum reservoir to maintain the set speed when climbing a hill. This electronic system is accurate enough so that any speed from
25 to 85 mph can be selected and maintained. The electronic control also permits the system to conserve engine vacuum.
The system has the following safety features:
Rapid deceleration cutoff Turns the system off if a 10 mph/sec deceleration rate occurs even if there is no indication that the brakes have been
applied.
Wheelspin cutoff Disengages the system if the set, resume, brake or clutch switches do not close and reopen when actuated or if a wiring
malfunction occurs in these circuits. This prevents the system from operating in an unexpected manner because of a system malfunction.
Brake and/or clutch switch(es) Release all vacuum when pedals are depressed, thus releasing the throttle. The switches also open the ground
circuit which signals the control unit to release the throttle.
Brake light switch When activated supplies 12 volts to the control unit's ground circuit, effectively cancelling the ground. This signals the control
unit to release the throttle.
Operating instructions
The cruise control system is electrically actuated and vacuum operated. The multifunction control lever incorporates a slide switch with 3 positions,
OFF, ON, and RESUME. The SET button is located at the end of the turn signal lever. The system is designed to operate at speeds above 25 mph.
WARNING: THE USE OF THE CRUISE CONTROL SYSTEM IS NOT RECOMMENDED WHEN DRIVING CONDITIONS DO NOT
PERMIT MAINTAINING A CONSTANT SPEED, SUCH AS IN HEAVY TRAFFIC OR ON ROADS THAT ARE WINDING,
ICY, SNOW COVERED, OR SLIPPERY.
To engage: Turn the unit on and press the set button to engage the system and enter the speed into the control module's memory. Release the
accelerator; speed will be maintained at the present level. Moving the slide switch from OFF to ON while vehicle is in motion provides power to
the module without system engagement.
To disengage: Normal brake or clutch application, or a soft tap on the brake pedal will disengage control unit without erasing speed memory.
Moving slide switch to OFF position or turning ignition off also disengages the system and in addition erases the speed memory.
To resume after braking: Momentarily move slide switch to RESUME. Vehicle will resume to previously memorized speed.
To vary speed setting: To increase speed, depress accelerator to desired speed and momentarily push and release SET button.
When speed control system is engaged, tapping speed SET button will increase speed setting in 2 mph increments.
To decrease speed, tap brake pedal lightly to disengage system. When desired speed is reached, push and release SET button. A decrease in speed
can also be achieved by holding SET button against stop until desired speed is reached. Releasing the button engages the system at that speed.
To accelerate for passing: Depress accelerator as necessary. When passing is completed, release accelerator and vehicle will return to previous
speed setting.
Operation
The servo valve housing contains two vacuum solenoid valves which the control unit uses to control speed regulation. When energized, the supply
solenoid applies vacuum to the servo to open the throttle and increase speed.
The vent solenoid holds vacuum in the servo when energized, to allow speed to increase or remain constant. When de-energized, it releases vacuum to
allow the throttle to close.
When operating on a level road, both supply and vent solenoids are closed most of the time so that airflow through the system is minimal. A vacuum
supply is needed only to set, resume or open the throttle to maintain speed on a hill.
A one-way check valve is used to trap vacuum in the vacuum reservoir. When engine vacuum drops, as in climbing a hill, the reservoir supplies the
vacuum needed to open the throttle and maintain speed. The vent solenoid remains closed during hill climbing and constant throttle operation to make
