Principles of Operation

PRINCIPLES OF OPERATION

The speed control system is designed to maintain a selected vehicle speed between approximately 48 and 200 km/h (30 and 125 mph).

The electronic stepper motor (internal to the speed control servo) is controlled by turning the 3 phases of the motor on and off in sequence. The sequence determines the motor direction (open throttle or closed throttle based on vehicle speed).

Whenever the system is engaged and active, a speed control set indicator will be illuminated in the instrument cluster.

The brake pedal position (BPP) switch is a normally open switch. When the brake pedal is applied with the speed control system engaged, the BPP switch closes, putting the vehicle speed control in stand-by mode.

NOTE: The deactivator switch is provided as an additional safety feature.

Normally, when the brake pedal is pressed, the speed control servo will deactivate the speed control system. Under increased brake pedal effort, the deactivator switch, a normally closed switch, will open and remove power to the speed control servo clutch, releasing the throttle independent of the PCM.

The clockspring provides the electrical interface between the steering column wiring and the speed control switches in the steering wheel.

The inputs to the speed control servo are:
- vehicle speed signal
- speed control switches
- brake pedal position (BPP) switch
- deactivator switch

The outputs of the speed control servo are:
- speed control indicator
- speed control cable controlling the throttle position