Cruise Control Module: Description and Operation

The Speed Control Amplifier controls vacuum to the Speed Control Servo Motor through the Modulating Valve. The Servo Motor moves the throttle through the Actuator cable.

To operate the Speed Control System, the engine must be running and vehicle speed must be greater than 30 mph. The system is turned on to standby mode by pressing the ON switch of the Steering Wheel Control Switch.

SET/ACCEL or COAST

Pressing and releasing SET/ACCEL or COAST send a command to maintain the present speed. This speed becomes the set speed. The Vehicle Speed Sensor sends signals to the Speed Control Amplifier. These signals tell the amplifier to increase or decrease the vacuum at the Servo Motor to keep the vehicle at the set speed.

SET/ACCEL

Pressing the holding SET/ACCEL speed up the car. The vehicle's speed increases as long as SET/ACCEL is depressed. Releasing SET/ACCEL gives the system a new set speed to maintain. Vehicle speed can also be increased by depressing the accelerator until the higher speed is reached, then depressing and releasing SET/ACCEL.

COAST

Pressing and holding COAST slows down the vehicle. The vehicle speed decreases as long as COAST is depressed. Releasing COAST gives the system a new set speed to maintain.

OFF

Press OFF turns off the system (grounds 151 [LB/BK] wire) or the Ignition Switch is turned OFF. The Vacuum Dump Valve also operates when the brake pedal is depressed. This is a backup device to release the servo.

In vehicles with manual transmission, the Speed Control Amplifier monitors a ground reference input through the Clutch Switch, the 810 (R/LG) wire and the Stop Lamp bulbs. When the clutch pedal is depressed, the ground is open and the Speed Control System turns off.

RESUME

When the system has been deactivated by depressing the brake or clutch pedal, the last speed may be resumed by pressing RESUME. This feature will not work if OFF has been depressed or if car speed drops below 30 mph.