Cruise Control: Description and Operation

The speed control system is operated by means of five switches on the steering wheel. The functions are:







The control unit provides signals to the stepper motor housed in the actuator. The stepper motor moves the throttle body cam by means of an internal geartrain and a cable linkage. The vehicle speed sensor generates the reference signal that the control unit compares to the speed setting selected by the driver. If a discrepancy exists the stepper motor will adjust the throttle body cam setting, correcting the vehicle's speed.

Any of the switches operated by the brake or clutch pedal will interrupt the speed control operation by releasing the speed control actuator cable and returning the throttle body cam to idle.







Speed Control Actuator
The speed control actuator is mounted on the right-hand inner fender behind the suspension unit top mount. The speed control actuator incorporates the following components:
^ The electronic speed control unit
^ The stepper motor and geartrain, electromagnetic coupling and reduction gearing







Speed Control Unit
The speed control unit evaluates incoming signals from the system sensors and switches. It actuates a stepper motor and cable linkage to adjust the throttle body cam, maintaining a constant vehicle road speed.

If the vehicles brake or the clutch pedal are depressed, the speed control unit interrupts the speed control operation.







Stepper Motor
When the speed control system is activated, the windings in the stepper motor are energized by the speed control unit ensuring accurate positioning of the throttle body cam. The vehicle road speed then settles to the speed selected by the driver.







Actuator Switches
When the ON switch is pressed and the vehicle is travelling at a speed greater than 25 mph the speed control system will accept speed inputs.







Pressing the SET/ACC switch at any speed in excess of 25 mph causes the vehicle to accelerate or maintain the present speed. The switch can be used in two ways.
^ Press the SET/ACC switch and hold it down until the vehicle reaches the desired speed. When released, the speed is stored in the memory and used to maintain the vehicle speed.
^ Press the SET/ACC switch repeatedly in order to increase the road speed in steps of approximately 1 mph.







The COAST switch is used to reduce the vehicle's road speed. The switch can be used in two ways:
^ Press and hold it down until the vehicle slows to the desired speed. When the switch is released, the speed is stored in the memory and used to maintain the vehicle speed.
^ Press repeatedly to reduce the vehicle road speed in steps of approximately 1 mph.







Pressing the RES switch automatically resumes control at the set speed.







Pressing the OFF switch deactivates the speed control system. The speed setting stored in the speed control unit memory will be erased.







Stop Lamp Switch, Brake Pedal
If the brakes are applied while the speed control system is active, the speed control unit receives a signal from the stop lamp switch. This causes the stepper motor to close the throttle body cam under stepper motor control.







Deactivator Switch, Brake Pedal
If the brakes are applied forcibly while the speed control system is active, the control unit receives a signal from the deactivator switch. This causes, the electromagnetic actuated coupling on the stepper motor to immediately disconnect the motor from the throttle body cam allowing, the cable and throttle body cam to close rapidly under throttle return spring control.







Clutch Pedal Position Switch
When the clutch pedal is depressed, the clutch pedal position switch causes the electromagnetic actuated coupling on the stepper motor to immediately disconnect the motor from the throttle body cam, allowing the cable and throttle body cam to close under throttle return spring control.