Cruise Control: Description and Operation

The Cruise Control system operates a mechanical linkage to the throttle by means of a Vacuum Motor, This is a diaphragm moved by a vacuum applied to one side. A solenoid operated valve connects the Vacuum Motor to engine vacuum. Another Solenoid Valve vents the vacuum to reduce suction. The Cruise Control Module controls the Vacuum Motor and the throttle by pulsing these solenoid valves on and off.

The inputs to the Cruise Control Module for control of the Cruise Control system are:

^ Cruise On from the Cruise Control Switch.
^ Brake Inputs from the Brake Switch and the Vacuum Release Valve.
^ Vehicle Speed from the Vehicle Speed Sensor Buffer to determine if the actual vehicle speed is different from the cruise set speed.
^ Servo Position from the Cruise Control Servo. The Servo Position Sensor in the Cruise Control Servo senses the position and motion of the Vacuum Motor. The Cruise Control Module uses this information to provide smooth acceleration when in the cruise mode.
^ Set/Coast from the Set/Coast Switch by applying battery voltage to Cruise Control Module terminal L when operated.
^ Resume/Accel from the Resume/Accel Switch by applying battery voltage to Cruise Control Module terminal M when operated.

There is also a vacuum shutdown of the Cruise Control Servo. The Vacuum release Valve, on the brake lever support, vents all vacuum from the Vacuum Motor whenever the brake pedal is depressed.

Two outputs at Cruise Control Module terminals K and C operate the Vacuum and Vent Valves in the Servo. These valves move the throttle through the Vacuum Motor. The Cruise Control Module pulses these valves on and off as necessary to maintain the proper vehicle speed.

The CRUISE ENGAGED Indicator in the Cruise Control Switch is controlled through circuit 400 by the Cruise Control Module. The Module grounds circuit 400 to turn on the indicator when Cruise is engaged.