How ABS System Can Save Your Life

What Is The Purpose Of ABS In A Vehicle? Why Do You Need ABS?

When brakes are applied by the driver, the rotation of the wheels is stopped, but the vehicle remains in momentum which causes the vehicle to continue moving even after the wheels have stopped. This is because of the inertia of the vehicle that causes the vehicle to continue moving  forward despite the locked wheels due to braking action.  This results in the car sliding or skidding instead of coming to a smooth stop. A locked-up wheel starts skidding and has no traction (grip of the tires with the road) as compared to a non-skidding wheel since the skidding wheel simply glides over the ground surface. 

This is really dangerous since high-speed braking can cause loss of traction and the driver can lose steering control over the vehicle. Hence, it becomes imperative to maintain traction while braking and gaining control over the vehicle. This can be done by employing a system called Anti-Lock Braking System (ABS) which prevents the locking up of the wheels and retains control over the vehicle during braking.

What Are The ABS System Parts?

The ABS is designed to prevent wheel lock-up and maintain steering control and traction between the tires and road surface. The ABS is especially beneficial on both dry and slippery surfaces as it reduces the stopping distance. It does so by monitoring the speed of the wheels and adjusting the brake pressure applied at the wheels to effectively stop them along with the vehicle and avoid wheel slippage and vehicle skidding. 

The ABS mainly consists of four elements - Sensors, Valves, ECU, and HCU.

  • Sensors: Wheel speed sensors continuously monitor the real-time speed of the wheels. This enables the sensors to detect any sudden changes in wheel speed, whether it's rapid deceleration or acceleration. They also monitor the rate at which deceleration occurs.
  • Valves: They control the amount of hydraulic pressure applied to the brake unit. There are three different positions for these valves. In the first position, the brake valve is open, allowing the pressure from the master cylinder to be transferred to the brakes. In the second position, the brake valve remains closed, restricting the flow of pressure from the master cylinder to the brakes. In the third position, the valve releases a portion of the pressure to the brakes.
  • ECU: This is an Electronic Control Unit that operates the ABS system. The data collected from the sensors is analyzed by the ECU which then calculates the rotational speed and acceleration/deceleration of each wheel. Based on this information, the ECU adjusts the brake pressure through the Hydraulic Control Unit (HCU).
  • HCU: The hydraulic control unit (HCU) consists of a pump and accumulators. It receives signals from the ECU to alter the brake pressure applied to the brakes. In case of low pressure, the pump is actuated to apply the required pressure to maintain effective braking.

How Does ABS Work?

The ABS works by monitoring the speed of each wheel compared to other wheels and also the rate at which deceleration of each wheel takes place. While braking, the speed of the wheel is different from that of the vehicle. That causes the wheels to drag, skid or slide across the road instead of rolling and thus, results in loss of control of the vehicle.

When the brake pedal is depressed by the driver, the wheels receive hydraulic pressure through the ABS valves which are then transmitted to the brakes. The valve consists of solenoids that are connected to the ABS ECU. This allows the ECU to actuate the valve and control the flow of the pressure. The ABS sensor continuously monitors the speed of the wheel as well as the rate of deceleration. It uses this information to  determine if the wheels are on the verge of locking up. When such a situation is detected, the ABS system releases the brake pressure by cutting off the supply through the valve. 

Then it monitors the acceleration of the wheel and reapplies the brakes using the hydraulic pump pressure. This process of releasing and reapplying the brakes occurs rapidly, cycling approximately 15 times per second.  This procedure allows the wheel to retain its grip on the ground by maintaining the wheel in a position where the braking effect is maximum (which is right before the wheel locks up). Doing this allows the driver to steer the vehicle since the traction is still present at the tires and allows control over the vehicle. The stopping distance of the vehicle is also reduced since skidding is prevented.

How Does ABS System Save Your Life?

The ABS system is designed to stop the vehicle from skidding and losing control of the vehicle while braking. When braking in a non-ABS vehicle, all the wheels are stopped immediately as the brakes are applied. This causes the driver to lose control over the vehicle, causing it to skid, swerve, and roll. The driver also loses steering control while braking since the wheels are skidding and not rolling. ABS system helps maintain steering control and traction so that the driver can stop the vehicle in any situation without worrying about losing control. Having the ABS system in your vehicle can help avoid accidents caused due to loss of vehicle control.

Most older cars have been equipped with ABS as standard since the early 1980s, and it has been mandatory for all North American cars since 2012. Therefore, you do not have to worry whether your car has ABS or not. However, is it important that you make sure that the ABS system in your car works properly.

How To Inspect The ABS?

To inspect the ABS, follow these steps: 

  • First, start the vehicle and check the ABS warning light. If the light does not illuminate, it may indicate a problem with the system. 

  • Next, perform a visual inspection of the ABS components for any signs of damage or wear. 

  • Check the brake fluid level and ensure it is within the recommended range. 

  • Finally, test the ABS system by performing a controlled stop on a safe, dry surface. 

If the brakes do not engage properly or there is a delay in stopping, it may indicate a problem with the ABS.

What Are The Symptoms Of ABS System Failure?

The ABS system on most modern cars combines hydraulics, electronics, and mechanical components and so the likelihood of failure is quite high. The most commonly replaced ABS system parts include wheel speed sensors, ABS valves, and hydraulic pumps.

ABS Warning Light

The first and most obvious sign of ABS failure is a warning light on the dashboard. ABS warning lights usually occur when there is an electrical issue with the system, like a broken wheel speed sensor or faulty ABS control module. A diagnostic tool can help you determine the underlying problem. However, older vehicles equipped with ABS systems typically lack a dedicated ABS warning light. Instead, they share the "Check Engine" light. This means that if there is a malfunction or issue with the ABS system, the "Check Engine" light might illuminate to indicate a problem. It is always wise to investigate an ABS warning light, since the issue can be a simple wiring problem or trouble with the ABS module.

Unresponsive Brake Pedal

If depressing the brake pedal yields no result, then there is a definite issue with either the ABS or brake system. This issue usually develops over time and you might notice a gradual decrease in braking response that eventually ceases completely and results in an unresponsive brake pedal. The problem may arise due to clogged ABS hydraulic valves, broken brake lines, faulty brake master cylinder, or a leak in the brake hydraulics. Have your vehicle's ABS and brake system inspected immediately before the damage gets worse.

Increased Brake Pedal Effort

The brake pedal is supposed to feel firm, but the braking response should also be immediate and constant. A variation in the brake pedal feel or a noticeable increase in the amount of force required to brake can be a sign of ABS failure. This can be caused by either a malfunctioning ABS module or a failing ABS pump. If left unchecked, the brakes in the vehicle can be completely compromised. It is  recommended you get your vehicle inspected as soon as possible.

Brakes Locking

The ABS system is intended to prevent wheel and brake locking up and so in the event of its failure, you can expect those issues to occur. Wheel locking causes the vehicle to skid and diminishes traction of the tires with the ground surface. This means the vehicle will take significantly longer to stop and the driver will also have no steering control while braking. If your ABS system is acting up, then you may notice the vehicle takes much longer to stop and the brakes lock up even during normal driving conditions. These issues can occur due to a bad ABS control module or ECU. Also, inspect the brake calipers and brake pads for any sticking issues. 

The ABS system in your vehicle is extremely important safety equipment that needs to be kept in proper working condition for safe and efficient driving and braking experience. In case you notice issues with the ABS system, then have it inspected and replace any faulty components to restore the system to its factory state. You can actively take measures to ensure the ABS and brake system components last longer.

How To Maintain The ABS?

To maintain the ABS system, it is important to follow the manufacturer's recommended maintenance schedule. This typically includes regular brake fluid flushes, inspections of the brake lines and hoses, and replacement of any worn or damaged components. It is also important to drive cautiously and avoid sudden stops or aggressive driving, which can put additional stress on the ABS system. Regularly checking the ABS warning light and addressing any issues promptly can also help to prevent any serious problems from developing. By following these steps, you can help ensure that the ABS system is functioning properly, thereby enhancing safety while driving.


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ABS is a critical safety feature. Driving with ABS disabled can significantly reduce the braking performance of the vehicle, especially during high-speed braking. The vehicle also becomes susceptible to hydroplaning on wet surfaces and the possibility of skidding is much higher. The bottom line is that driving with ABS disabled is highly discouraged and there is a definite reason why it is installed by manufacturers and even mandated by law (as standard equipment) in certain countries.

When the ABS is working properly, the driver can notice a certain pulsation action from the brake pedal while braking. This can also be accomplished by grinding and buzzing noises, which simply means the ABS system parts are at work. The brake pedal pulsates as the hydraulic pressure within the brake lines is moderated by the ABS system. If you feel this happening, then do not let go of the brake pedal as it only means the ABS is working.

While ABS is not vital for breaking, it still is a significant safety feature that is standard on most vehicles today. The brakes can still be applied without ABS functioning, but in such cases, you will experience a loss of control over the vehicle during heavy braking scenarios. The wheels will lock up, causing the vehicle to skid, which leads to increased stopping distances and disables steering.

The ABS only works when braking from speeds above 25 km/p (12 - 15 mph). At lower speeds, the wheels do not suffer locking and so ABS functionality becomes redundant.

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John Framigllia
Technical Writer
Our technical writer is known for simplifying automotive parts and services. Intuitive with various vehicles and manufacturers, he knows how to simplify complicated problems.