Principles of Operation

WARNING: This page is about a different car, the 2003 Mercury Sable and 2003 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 speed above 48 km/h (30 mph). After the speed control actuator switch ON is depressed, depressing the speed control actuator switch SET/ACCEL will activate the speed control servo.

To increase a set speed, either depress and hold for continuous acceleration, or momentarily tap the speed control actuator switch SET/ACCEL for 1.6 km/h (1 mph) acceleration increments. To decrease a set speed, depress and hold the speed control actuator switch COAST until the target speed is reached, or momentarily tap the speed control actuator 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 actuator switch RESUME can be depressed 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 actuator switch OFF has not been depressed.

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

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

The inputs to the speed control servo are:

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

The outputs of the speed control servo are:

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