What is the Speed Control Assembly?
Cruise control, or speed control, is used to keep a speed when driving at highway speeds. It not only relieves the driver from constantly pressing on the accelerator, but improves fuel economy thanks to less throttle fluctuation. The speed control assembly is a servo that works to hold the throttle steadily open when the cruise control is set. It is a vacuum-operated part that has a chain or cable running between it and the throttle pivot. When the cruise control is set, the cable tightens to hold the accelerator position. Pressing the accelerate or coast buttons on the cruise control will either increase or decrease the about of pull the servo exerts. If the speed control assembly or servo is not working correctly, the cruise control may not set at all or have difficulty maintaining a constant speed.
Bear in mind:
- The speed control assembly is also refered to as the cruise control servo.
How it is done:
- The car battery is disconnected for safety
- The defective speed control assembly is taken out
- The new speed control assembly is mounted
- The battery is reconnected and any programming is done
- The car is road tested and speed control operation is checked
The speed control assembly does not require maintenance or servicing, and should last the lifetime of your vehicle. If something does cause the speed control assembly to fail, or you suspect the speed control assembly is the cause of your cruise control issues, have an expert mechanics diagnose and change it if necessary.
What common signs indicate you may need to replace the Speed Control Assembly?
- Cruise control does not set
- Speed control will not maintain a set speed
- Other vacuum-operated functions, such as heater controls, do not work correctly
How important is this service?
Cruise control is not a mandatory part on vehicles, and many are still manufactured today without speed control. As such, it is an accessory. If it does not work properly, it does not present a safety risk. Don’t use the cruise control until you have the speed control assembly changed.
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