Anti-lock Braking System (Expert Guide)

The anti-lock braking system is also commonly called ABS or anti-skid braking system. While its history doesn’t go as far back as automobiles, it’s quite relevant to modern vehicles. A French pioneer, Gabriel Voisin, developed the very first ABS in the 1920s. He built it to supplement braking on airplanes. The anti-lock braking system would be used for this purpose for the next few decades.

anti-clock braking system

In the 1970s, however, car manufacturers adopted ABS and introduce it to vehicles. It didn't take long for it to become a common feature in modern-day cars, buses, and even motorcycles. Now, the anti-lock braking system is a standard feature on nearly all new vehicles to supplement steering and traction controls while braking.

What is the anti-lock braking system?

ABS is a piece of automatic safety device designed in vehicles to work using threshold and cadence braking principles. It functions to prevent their wheels from locking up under tasking braking conditions like an emergency or panic. Virtually all modern two- and four-wheelers come fitted with an anti-skid braking system. This is in adherence to prevailing safety regulations for automobiles.

Car tires may immediately lose traction with the road surface when you suddenly step down on the brake pedal. This can cause the tires to skid, often uncontrollably, making the situation worse.

As is usually the case, the car continues in motion as the loss of traction consequently causes the driver to lose control over the steering wheel. A more drastic turn of events would lead to an accident or even death. But car manufacturers built the anti-lock braking system can forestall this mishap.

anti lock brake

Generally, ABS provides advanced automobile capabilities and can control stopping distances on any available surface. Since its introduction in cars, the anti-lock braking system has seen continuous advancement to become a really effective car component.

It has gone by different names over time, some of which include a traction control system, electronic brake-force distribution, emergency brake assist, and electronic stability control (ESC). There’s no telling what it can advance to become in the future or what new name it will be called.

How does an anti-lock braking system work?

ABS gets to work when you release and then reapply the brake of your car in a sudden, heavy braking situation. Wheel speed sensors are mounted on the wheels. These sensors are designed to monitor the speed of each wheel. So, when your car wheel locks up, stops moving, or/and starts to skid, the sensors pick it up and send it to the electronic control unit (ECU).

ABS Sensor

In turn, the ECU transmits the signal to the valves of the various wheels. The valves then reduce the brake and close. Afterward, the wheels resume acceleration and the sensors notice the change and send the information to the ECU again.

The ECU, again, sends the signal for the valves to reopen and increase brake pressure, therefore, applying the brakes. The process repeats until brake application becomes normal.

To put it simply, ABS pumps the brakes the moment a wheel lock-up is detected at the incredible rate of 100's of times a second. This application prevents the car wheels from skidding, as well as helping the driver maintain control of the steering wheel. Anti-lock braking systems essentially works in three stages:

  1. Foot presses down on the brake pedal
  2. Wheel sensors detect skidding or wheel lock-up
  3. ABS pumps the brakes


Components of ABS

Every automobile component is made up of subcomponents. The anti-lock braking system basically comprises five primary components: speed sensors, valves, a pump, brake fluid, and a controller.

Speed sensors

Speed sensors are mounted on the car wheels to monitor how fast they are rotating. They typically consist of toothed rings and magnets encased in a coil.

The rings make calibrated contact with the magnets to induce electric fields, thereby generating a signal. It’s this signal that the sensors send to ECU. The speed sensor is a crucial component of the anti-lock braking system and the general car braking system.


abs pump

ABS pump in an engine[/caption]ABS pumps are employed to restore the pressure released by the valves to the hydraulic brakes.  Filled with hydraulic fluids, they basically apply pressure to the brake drums or calipers as needed. The status of the pump influences the amount of pressure to be produced and how the ABS functions. The ABS controller determines the status.  


Valves in the ABS line function to control brake pressure by taking three different positions; open, close, and release positions. First, the open position will let the pressure go through the brakes. While the close position blocks any extra pressure, limiting the pressure on the brake.

Lastly, the release position helps to dissipate the pressure stored on the brake. When you press your foot on the brake pedal hard, the valves reduce the pressure on the brakes. A faulty valve will disrupt the smooth functioning of the ABS. It will hinder the anti-skid braking system from controlling the brake pressure.

Brake fluid

It’s a good time to remind you that we are discussing the hydraulic brake fluid system. Here, the brake fluid is the primary applicator of the brakes. It transfers force from the hydraulic lines to the braking device situated close to the wheel.

Car brakes generate a lot of heat during operation. But the high boiling point of the brake fluid facilitates smooth functioning. Also, the fluid guides against corrosion of contacting materials.


ECU in a car

Controller is the electronic control unit (ECU). The controller is to ABS what the brain is to the human body. It collects data from the speed sensors, processes it at an incredibly fast rate, and determines what functions to perform.

For instance, the controller can get a signal from the sensor and relay it to the pressure modulator. This seemingly simple process controls the ABS valve, and by extension, the respective speed of the wheels.

Functions of the anti-lock braking system

The primary function of the anti-lock braking system is to prevent the skidding of vehicles when the brake is applied suddenly. It can also come in handy when cars are on slippery road surfaces. Generally, it prevents car wheels from locking up and offers better control over car brakes.

The car slows down even as the tires maintain a grip on the road. Meanwhile, the obtainable traction lets the driver handle the steering wheel well. ABS works using the threshold braking principles. Normally, these principles are used by skillful, competitive drivers to stop their cars from skidding. Now, it’s available in virtually all modern cars.

Benefits of ABS

The anti-skid braking system supplements normal brakes and offers some significant benefits.

  • ABS considerably prevents the likelihood of your car wheels from locking up and skidding. This is especially useful in slippery conditions or under severe braking conditions. Often, the ABS can be a lifesaving mechanism in dangerous scenarios.
  • Since ABS lowers the risk of accidents, it can help you keep down your vehicle insurance payments. You will be saving money.
  • It increases the efficiency of tires by up to 30% by reducing the friction of car wheels on the road. ABS makes car tires to be resistant to wear.
  • By effectively controlling the steering, ABS prevents overturning of vehicles. It makes for easy steering.
  • There is a faster response to braking, making for a short brake-path.

Can ABS get bad?

Yes, it can and it often does. And when this happens, incidents like traction loss, hydroplaning, and skidding may occur under heavy braking situations.

What causes ABS damage?

Anti-lock systems are designed in such a way that they give several warnings when it’s faulty. It’s crucial to be aware of these warning signs and deal with them as soon as they arise. They are as follows:

The pedal may become unresponsive

Car pedals

The fault is quite easy to spot. The brake pedals of most vehicles may become unresponsive when ABS starts to fail. Such brake pedals won't be able to stop a car, at least, not effectively. This fault develops over time.  

As a rule, the brake pedal should respond easily if all braking system components are functioning optimally. A brake pedal should press down seamlessly and cause the vehicle to slow down. If this is not the case, then something may be wrong with your ABS.

Wheels may lock up

As you know, the ABS, if it’s working correctly, is supposed to prevent wheels from locking up during heavy braking. However, a bad ABS can stand in the way of this.

Speedometer can malfunction

This is a rare case. A faulty ABS can cause the car’s speedometer to stop working. It’s usually one of two outcomes; it will either display incorrect speed or the needle will remain at 0 mph.

The ABS light comes on

This is, by far, the most common sign of anti-lock braking system failure. The amber-colored ABS Light is similar to Check Engine Light, except it precisely signifies a problem with the ABS. Whenever the ABS Light comes on, take it as a sign to take your car to an ACE-certified mechanic for repair.

ABS light

What can cause your ABS light to come on?

Clearly, something is wrong with your anti-lock braking system if the ABS Light comes in your dashboard's instrument cluster. Below are some of the reasons it may come on:

Faulty ABS controller

A damaged module will cause your ABS Light to come on. This is often due to wire corrosion which can cause delay or hinder communication between stepped sensors and the ABS. Even a little corrosion can result in significant damage. You may have to replace the computer in the module.

Low brake fluid

Low brake fluid

Check your brake fluid reservoir[/caption]First, your brake system is hydraulic. Here's what it means: the power of the cylinder presses against a fluid, closing your brake pad and stopping your vehicle. So, you need to maintain a certain fluid level to keep your brake system working in optimal condition. Your ABS Light will come on if the brake fluid is low.

Broken wheel speed sensor

The anti-lock braking system depends on the signals from the speed sensor to function. If the ABS module detects something wrong with it, the ABS Light will come on. Other reasons include unresponsive valves, block pumps, a blown fuse, or a turned-off system.

Some common questions about ABS from car users

How can you turn off the ABS light?

To turn it off, you will have to fix whatever is wrong with your ABS. You can use a diagnostic tool to figure out what. If nothing is wrong, you may have to reset the whole ABS equipment.

How can you reset the ABS using a diagnostic tool?

Using an OBD scanner

Using an OBD scanner[/caption]Plug your OBD scanner into your vehicle's computer. It will return any error code it detects in the system. The error code will tell exactly what's wrong with your ABS (you can check online to decipher meaning). Once you repair the damage, move on to input the provided clear code into the OBD scanner. This will reset your ABS Light and consequently turn it off.

Can ABS lock your break?

When it's in good condition, the ABS is built to precisely prevent car wheels from locking up under heavy braking. So, no. However, a broken ABS can cause your car brakes to lock up even under normal driving conditions.

Can low brake fluid cause ABS light to come on?

Yes, it can. The ABS light comes on whenever your car detects a problem In your anti-lock braking system.

Can you drive your car with the ABS light on?

Yes, you can since it does not stop your car from moving. Nevertheless, it's not safe as your car brake may not be effective when you need it.

Is it safe to disable the ABS?

No, it's not safe. When you disable your anti-lock braking system, your brake begins to function as non-ABS. And this will drastically reduce the effectiveness of your car's braking system.


Everything we have discussed in this article points to the fact that ABS is a crucial component in vehicles. It supplements the effort of the main braking system. And like all devices, it can become faulty. Ensure to watch out for the signs listed in the article to promptly repair it when due.

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