Cruise Control: Description and Operation

The speed control system consists of these components:
^ Speed control servo
^ Speed control actuator cable
^ Vehicle Speed Sensor (VSS)
^ Horn relay and bracket
^ Speed control actuator switch
^ Stoplight switch
^ Deactivator switch
^ Brake pressure control valve
^ Air bag sliding contact

The system operates independently of engine vacuum; therefore no vacuum lines are required.






The speed control servo:
^ Is mounted under the LH front fender, forward of the wheel.
^ Connects to the throttle linkage with a speed control cable.
^ Integrates system electronics, eliminating the need for any other speed control electronic modules in the vehicle.






The speed control switch:
^ Is mounted in the steering wheel.
^ LH buttons (ON, OFF).
^ RH buttons (RESUME, SET, ACCEL, COAST).
^ Necessary wiring.






The vehicle speed sensor (VSS):
^ Is mounted to the transmission.
^ Is a magnetic pickup driven by a gear which is driven by the transmission.
^ Sends a signal to the speed control servo proportional to vehicle speed.

The air bag sliding contact:
^ Is located at the center of steering wheel.
^ Transfers the electrical signals from the steering column wiring to these components:
- Driver side air bag module
- Horn blow switch
- Speed control actuator switch






The stoplight switch:
^ Is a normally open switch that closes when the brake pedal is applied.
^ Sends an electrical signal to the speed control servo when closed and disengages speed control system.
^ Returns to its open position when the brake pedal is released.






The deactivator switch:
^ Is a normally closed switch.
^ Replaces the speed control dump valve as a redundant safety feature in the system.
- Under normal conditions, when the brake pedal is applied, an electrical (brake on/off) signal from the stop lamp circuit to the speed control servo will disengage the system.
- Under increased brake pedal efforts (36-67 [9-15 lbs] engine running), the deactivator switch will open and remove power to the speed control servo, releasing the throttle from servo control.
^ Is located at the front RH frame rail to the rear of the air suspension compressor.