Principles of Operation

WARNING: This page is about a different car, the 2005 Mercury Sable and 2005 Ford Taurus. However, it is still accessible from the selected car via links, so may be relevant.

The speed control system is designed to maintain vehicle a set speed above 48 km/h (30 mph). After the speed control ON switch is pressed, pressing the speed control switch SET/ACCEL will activate the speed control actuator. To increase a set speed, either press and hold for continuous acceleration, or momentarily tap the speed control switch SET/ACCEL for 1.6 km/h (1 mph) acceleration increments. To decrease a set speed, press and hold the speed control switch COAST until the target speed is reached, or momentarily tap the speed control switch COAST for 1.6 km/h (1 mph) deceleration increments. When the speed control system has been disabled by tapping the brake pedal, the speed control switch RESUME can be pressed and the vehicle will return to the original set speed if the vehicle is traveling over 48 km/h (30 mph) and the speed control switch OFF has not been pressed.

NOTE: The deactivator switch is provided as an additional safety feature. Normally, when the brake pedal is pressed, an electrical signal from the brake lamp circuit to the speed control actuator will deactivate the system. Under increased brake pedal effort, the deactivator switch will open and remove power to the speed control actuator, releasing the throttle independently of the speed control actuator.

NOTE: 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 actuator are:

vehicle speed signal
speed control switches
brake pedal position (BPP) switch
deactivator switch

The outputs of the speed control actuator are:

speed control indicator lamp
speed control actuator cable controlling the throttle position