Cruise Control: Description and Operation

The speed control system is composed of On-Off, Set-Acc, Coast and Resume (if equipped) switches. The system contains vacuum hoses, servo (throttle actuator) assembly, speed sensor, amplifier, check valve assembly, and depending on model and year, a clutch switch, stop light switch or vacuum dump valve. To operate speed control system, engine must be running and vehicle speed must exceed 30 m.p.h. When ``On-Off'' switch is actuated, the system is ready to accept a set speed signal. When vehicle speed stabilizes (exceeds 30 m.p.h.), and the ``On'' switch is engaged, the operator may depress or release the ``Set-Acc'' button. This speed will be maintained until a new speed has been set, brake pedal has been depressed, or the system is turned off.



The speedometer sends speed information to the inputs of the speed control amplifier and tripminder. The signal is DC coupled and bipolar. When the ignition switch is in the RUN or ACC positions the signal on this line will be either less than -3 volts or more than +3 volts. When the vehicle is not moving and the ignition switch is turned from OFF to the RUN or ACC position, the signal will be at the negative voltage level. On every pulse from the encoder wheel, occurring every 4 inches of vehicle motion, the signal will change to the opposite voltage level.