One of the most common and useful driver’s assistants is cruise control. With its help, you can drive hundreds of kilometers and stay awake.
We will tell you how cruise control works and how to use it correctly and safely.
What is Cruise Control
Cruise control is a system that allows the car to independently maintain the speed set by the driver.
The advanced version – adaptive cruise control – is able not only to maintain speed, but also to keep a safe distance, slow down the car independently if necessary, and then accelerate the vehicle back up to the set speed. Automatic speed maintenance saves the driver from controlling the accelerator pedal and makes a long trip less tiring.
The usefulness of cruise control is demonstrated by its very history. Ralph Titor, a mechanical engineer who was blinded at the age of 5, had the idea of automating the process of automobile gas control. The inventor’s lawyer, who was then acting as a driver, often involuntarily slowed down and accelerated the car and could not maintain a constant speed.
Soon Ralph’s invention, which was given several names at once – Speedostat, Conrolmatic, Pressomatic, Touchomatic – quickly found application in the automobile industry. The first car with cruise control was the Chrysler Imperial of 1958, and the “cruise” itself was named Auto-pilot. Already in the 60s of the XX century, the system became really mass.
How Does Cruise Control Works
Essentially, “cruise” is a conventional servo drive with negative feedback. When the driver activates the system, it memorizes the accelerator pedal position and the current speed.
If the speed starts to drop for some reason (for example, when driving uphill), the electronics give a command to a special servo and increase the gas supply. When the speed on the contrary becomes high (for example, on a downhill slope), the electronics gives a command to reduce the gas supply until the fuel-air mixture is completely shut off – engine braking takes place.
Ralph Titor’s device to maintain a constant speed of movement tracked the speed of rotation of the cardan shaft of the car and the speed of rotation of the speedometer cable. A special electric motor, guided by the received data, adjusted the position of the throttle valve and thus provided a constant speed for the car. In many modern cars for opening and closing the throttle valve is used vacuum system with electronic control.
From a technical point of view, any car can be equipped with cruise control, but in the absolute majority of cases, this operation is carried out at the stage of vehicle assembly on the assembly line.
In addition to its main function (maintaining the set speed), cruise control perfectly fulfills another task – it saves fuel. Unlike a human, electronics doses the fuel supply more competently and smoothly, thereby reducing consumption by 4-7%.
Cruise control systems can be used both on cars with manual transmission and on models with automatic.
On an automatic
In cars with any type of automatic transmission, gear shifting is performed without the driver’s involvement, which greatly simplifies the operation of the cruise control system. It can operate without human intervention in difficult road conditions.
For example, when driving uphill, the car will shift down one or more gears on its own to maintain speed. The same will happen on a downhill slope when simply closing the throttle will not be enough to effectively slow down to a given speed.
On a manual
The manual transmission limits the operation of the cruise control system. Since the motorist has to be directly involved in the process of changing gears, the car can not always independently realize the possibilities of acceleration or deceleration in automatic mode.
For example, the cruise control may not be able to pull the car up a steep hill in high gear – this would require the driver to shift the transmission down. When driving downhill, another effect occurs: the system closes the throttle completely when the set speed is exceeded, but the car does not slow down efficiently enough. To further reduce the speed, the driver has to apply the brake himself or shift down a gear. However, when manipulating the pedals and gearbox, the cruise control system is deactivated.
How to use Cruise Control
Modern car cruise control is an electronic system controlled by buttons on the steering wheel or individual paddle switches. Regardless of the make and model of the vehicle, the system functions and controls similarly, although nuances are possible. To activate the system, you usually need to perform the following sequence of actions:
- Find the button on the steering wheel, paddle shifter, or console responsible for activating “cruise” and turn the system on (ON/OFF buttons). It is usually disabled by default. Information about the cruise control operation is displayed on the instrument panel.
- Accelerate the car to the speed you want to drive. Note that in most cases, cruises cannot operate at speeds below 40 km/h.
- Start the system by pressing the button or lever labeled SET/- or simply SET (depending on the model, the name may vary).
- Release the accelerator pedal – the car will begin to maintain speed without your participation.
The operation of the cruise control system may have individual peculiarities, which you should familiarize yourself with in the operating instructions. It is not uncommon for the manufacturer to include many features in the system.
For example, you can increase or decrease the set speed directly from the steering wheel. With a short press on the “+” the speed increases by 1 km / h, with a longer press – by 5 km / h. Similarly, the “-” button can be used to decelerate the vehicle. By pressing the Resume button, the system can be reset to the previously set value.
To switch on “cruise” on the car and start using it is only half a job. It’s also important to understand how to turn it off.
How to Turn off Cruise Control
Cruise control is usually turned off by:
- Pressing the brake or clutch pedal (if the car has an automatic transmission).
- Pressing the “pause” button.
- Activation of ESP or ASR systems.
- Shifting the automatic transmission selector to the N position.
When using cruise control, the driver can at any time exceed the programmed speed by pressing the accelerator pedal. For example, for overtaking. In this case, the “cruise” speed value on the display will start flashing. When the driver releases the accelerator pedal, the system will return to maintaining the previously set speed.
Types of cruise control
Cruise control systems are usually divided into two types – passive (PCC) and adaptive, aka active (ACC). They differ greatly in their capabilities.
Passive
About the principles of operation and capabilities of passive cruise control, we have already told above. This system has been operated for more than half a century on a variety of vehicles, but its abilities by modern standards are quite modest. In fact, such a “cruise” just maintains the speed regardless of external factors. It will not switch itself off if there is an obstacle in front of the car. Adaptive cruise is a different matter.
Adaptive
Active or adaptive cruise is a much smarter and more sophisticated system. This type of cruise control not only maintains the set speed but also tracks the speed of the car ahead, keeping a safe distance from it. In fact – chases the car-leader, estimating the distance to it and analyzing the speed of convergence and distance.
Unlike conventional “cruise”, adaptive cruise can engage the braking system to slow down or warn the driver of such a need (only up to 40% of braking power is used automatically, the remaining 60% is the driver’s prerogative).
A special digital radar and processor allows the car to select the speed and lag of the vehicle ahead. If a slower vehicle appears in front of the car, the speed is automatically adjusted to it. When the road becomes clear again, the car returns to the previously selected speed.
Advanced systems of adaptive “cruise” not only track the distance to another car but also control the correctness of the car’s movement relative to the road markings. The main advantage of such a system – increased safety.
How to Check the Cruise Control
Like any other system, cruise control can break down. In this case, the corresponding orange-colored icon lights up on the dashboard.
You should start looking for the cause of cruise control failure in any modern car by connecting a diagnostic scanner. Having read and decoded the error codes, you can understand which sensor and which electrical circuit need to be checked.
Also, experts recommend performing the following actions:
- Check the integrity of the fuse responsible for the operation of cruise control.
- Check if the vacuum system is in good working order.
- Evaluate the integrity of the wires going to the buttons or the cruise control lever.
- Clean the contacts on the controls (if possible).
- Check the serviceability of the limit switch on the brake pedal.
In most cases, cruise control failure is caused by mechanical damage to the wiring or vacuum system.
On some models, the cruise control performance can be checked using the self-diagnostic system.
On Honda CR-V the process is carried out as follows:
- After turning on the ignition, the Cruise Control system is activated by pressing the ON button.
- The system’s indicator light on the dashboard should illuminate. If it does not light up, the bulb must be replaced.
- Next, press the Resume Accel button and hold it for 3 seconds.
- If there are no breakdowns, the corresponding light should illuminate for 3 seconds and then go out for 2 seconds.
- If faults are detected, the light will begin to give their light codes.
- You can reset the self-diagnostic mode by accelerating to 16 km/h or turning off the cruise control by pressing the OFF button.
Refer to the reference literature and the owner’s manual for help in deciphering the trouble codes. It is important to remember that there are no universal methods of checking the Cruise Control system. The most correct thing to do when problems are detected is to contact a dealer or specialized specialists.
When it is not Allowed to use Cruise Control
Cruise control does not relieve the motorist of the need to control the traffic situation. Moreover, in conditions where it is impossible to maintain a constant speed due to dense or jagged traffic, its use is almost completely excluded.
It is explicitly stated in car manuals that cruise control must not be activated:
- When traffic is too dense.
- On emergency road sections.
- On roads with poor traction.
- In all difficult road conditions.
- When visibility is poor (at night, rain, snow, fog).
- On winding roads.
- On exits and access roads.
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