How does cruise control work?

Cruise control is a convenient feature that is present in many modern vehicles. It allows you to maintain your current speed while driving without having to keep your foot on the accelerator. With most vehicles, it is controlled via a control lever that looks like your indicator lever on your  steering wheel. In some newer vehicles, cruise control can even maintain a certain following distance, increasing your safety. This is called adaptive cruise control.

In order to understand your cruise control system, it is important to know what type of cruise control system your car uses:

Fully electric cruise control – In newer cars, the cruise control system is controlled by the ECU (electronic control unit). The ECU detects and applies the necessary throttle power to keep your car at a constant speed. 

Electromechanical cruise control – Unlike fully electric, electromechanical cruise control doesn’t use the vehicle ECU. Instead, a vacuum actuator is attached to the accelerator. This allows the acceleration to adjust depending on the vacuum sent from the actuator. This cruise control system is used mainly in older vehicles.


Causes of failing cruise control:

Blown fuse – The cruise control system is controlled by a fuse. If this fuse blows, the system will not be able to receive power. 

Faulty speed sensor – The speed sensor determines how fast your car is going. If it is not functioning properly, your cruise control system may not be able to maintain a certain speed.

Brake problems – The brakes disengage the cruise control system, allowing the vehicle to slow down. If there are any problems in your car’s brake system, or brake light switch the cruise control may not engage or disengage correctly.

Damaged ECU – The ECU is an onboard computer that controls the cruise control system in newer vehicles. If it is damaged, your cruise control system may not work properly.

Dirty or damage throttle control – modern vehicles use a “drive by wire” system that uses two variable resistors (potentiometers) on the top of the accelerator pedal. Data from these accelerator pedal position sensors is then sent to the engine ECU which then controls a stepper motors to determine the amount throttle opening.

Poorly adjust throttle position sensor – if the throttle position sensor (TPS) is not adjusted correctly or is damaged, then the engine ECU won’t have the correct information to make the correct calculations for cruise control speed.

Damaged vacuum actuator – The vacuum actuator controls the cruise control system in older vehicles. If the actuator stops working, the cruise control will not be able to function. An actuator problem can be caused by the actuator cable or vacuum hoses.


How important is fixing your cruise control system?

A faulty cruise control system can make driving with cruise control dangerous. If you suspect there is a fault in your cruise control system, don’t use it. In most cases, your vehicle will still run fine.

In some cases, a malfunctioning cruise control system can point to other faults in your vehicle. If you believe there is a fault in your throttle or braking system, we recommend that you get your vehicle inspected and diagnosed from your trusted local garage as soon as possible. 


Cruise Control Inspection in Hamilton

At Grimmer Motors, we can thoroughly inspect your cruise control system and diagnose the cause of issues. From there, we can replace any faulty parts and get your cruise control system working correctly, so you your family and other road users are kept safe.

For fast, reliable cruise control inspections/replacements in Hamilton, contact Grimmer Motors today!


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