Cruise Control: Description and Operation

The cruise control system uses mechanical, electrical and vacuum-operated devices to maintain vehicle speed at a setting selected by the driver.

System Description
The cruise control unit receives command signals from the cruise control switch. It receives information about operating conditions from the brake switch, the speedometer, the clutch switch (manual transmission) and the automatic transmission mode switch and Powertrain control module (PCM) (automatic transmission).

The cruise control unit sends operational signals to the devices that regulate the throttle position. The throttle position maintains the selected vehicle speed. The control unit compares the actual speed of the vehicle to the selected speed. The control unit then uses the result of that comparison to open or close the throttle.

The brake light switch releases the system's control of the throttle at the instant the driver depresses the brake pedal. The switch sends a signal to the cruise control unit when the brake pedal is depressed; the cruise control unit responds by allowing the throttle to close. The clutch interrupt switch or the automatic transmission mode switch sends a disengage signal input to the cruise control unit that also allows the throttle to close.

System Operation
The cruise control system will set and automatically maintain any speed above 25 m.p.h. (40 Kph). To set, press the cruise control main switch so that the "CRUISE MAIN" indicator is ON. After reaching the desired speed, press the set switch. The cruise control unit will receive a set signal input and will activate the cruise control actuator.

Pushing the cruise control switch cancels the cruise control system. This removes power to the cruise control unit and erases the set speed from memory. The cruise control system also disengages when cruising speed is lower than the preset speed by 12 m.p.h. (19 Kph) or more. If the system is disengaged temporarily by the brake switch, clutch switch or the automatic transmission mode switch and vehicle speed is still above 25 m.p.h. (40 Kph), turn and release the Resume/accel switch turned and released, the set memory is retained, the vehicle automatically returns to the previous set speed.

For gradual acceleration without depressing the accelerator pedal, turn the resume/accel switch and hold it there until the desired speed is reached. This will send an acceleration signal input to the cruise control unit. When the switch is released, the system will be reprogrammed for the new speed. Quickly turning and releasing the resume/accel switch allows you to tap up the preset cruising speed. Each turn increases the preset speed by 1 m.p.h. (1.6 Kph). The Preset speed can be increased by up to 10 m.p.h. (16 Kph) in this manner.

To slow the vehicle down, depress and hold the set/coast switch. This will send a deceleration signal input to the cruise control unit, causing the vehicle to coast until the desired speed is reached. When the desired speed is reached, release the set/coast switch. This will reprogram the system for the new speed. Quickly depressing and releasing the set/coast switch allows you to tap down the preset cruising speed. Each depress decreases the preset speed by 1 m.p.h. (1.6 Kph). The preset speed can be decreased to a minimum of 25 m.p.h. (40 Kph) in this manner.