Introduction
This page provides a factory-style overview of Ford Bronco II cruise control systems, including vacuum-operated and electronic cruise control designs used on 1984–1990 Bronco II models. It explains how each system functions, identifies major components, and includes diagrams to assist with diagnosis, troubleshooting, and repair.
Topics covered include cruise control servos, throttle actuators, control switches, speed sensors, brake and clutch deactivation switches, vacuum dump valves, and amplifier/control modules. Troubleshooting flowcharts and wiring diagrams are included to help identify common cruise control failures such as inoperative systems, failure to hold speed, or disengagement when driving.
Vacuum Systems
The vacuum-controlled cruise control system consists of the following components:
- Control switches
- Servo (throttle actuator)
- Speed sensor
- Clutch switch (manual transmissions)
- Stop lamp switch
- Vacuum dump valve
- Amplifier assembly
The throttle actuator is mounted in the engine compartment and is connected to the throttle linkage with an actuator cable. The speed control amplifier regulates the throttle actuator to keep the requested speed. When the brake pedal is depressed, an electrical signal from the stop lamp switch returns the system to stand-by mode. The vacuum dump valve also mechanically releases the vacuum in the throttle actuator, thus releasing the throttle independently of the amplifier control. This feature is used as a safety backup.
Fig. 1: Vacuum controlled cruise control system components
Electrical Systems
The electronic cruise control system consists of the following components:
- Control switches
- Servo/control unit (throttle actuator)
- Speed sensor
- Stop lamp and deactivator switches
The throttle actuator/control unit is mounted in the engine compartment and is connected to the throttle linkage with an actuator cable. The control unit regulates the throttle actuator to keep the requested speed. When the brake pedal is depressed, an electrical signal from the stop lamp and deactivator switches return the system to stand-by mode. This system operates independently of engine vacuum; therefore, no vacuum lines are required.
Fig. 2: Electronic cruise control system components
Cruise Control Troubleshooting
Wiring Diagrams:
Here are (2) wiring diagrams that may help as well:
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About The Author
Jim Oaks is a longtime Ford truck and SUV enthusiast and the founder of The Ranger Station and Bronco II Corral. With decades of hands-on experience, he writes both technical and non-technical articles covering the Ford Bronco II, including mechanical systems, factory engineering, common upgrades, and detailed feature vehicle write-ups.
In addition to technical content, Jim documents Bronco II history, rare factory and aftermarket models, production details, and original Ford marketing materials. His work is based on firsthand experience, original documentation, and long-term involvement in the Ford enthusiast community.
Through his sites, Jim has built comprehensive reference libraries that serve owners, builders, restorers, collectors, and historians, helping preserve the Bronco II’s technical knowledge and historical significance.