Have you ever slammed on your brakes to avoid a collision? Whether a car stopped suddenly in front of your or a green traffic light seemed to turn straight to red, there are many situations where a driver suddenly applies a significant amount of brake pressure. When this happens, you probably felt your brakes pulse. This is caused by your anti-lock braking system, or ABS. What is ABS? Learn more about this helpful safety feature, why it’s important and what to do if it isn’t working properly.

Understanding Your Anti-Lock Braking System

Applying a large amount of braking pressure even in perfect driving conditions will more than likely lead to a lock-up of the brakes, which locks the tires, and creates a loss of stability. What’s important to understand in the physics of driving is that a straight-line stop, even with tires in full lock-up is not where most of the dangers are presented. In fact, in most cases of a straight-line stop, a car will simply skid perfectly straight to a stop. When your brakes and tires are locked and not spinning, however, your car cannot steer, and herein lies the problem. In order for your car to properly steer and actually change directions, your tires have to be moving. Whether this is in perfect driving conditions, or wet, or snow – a panic stop is usually always coupled with another action – steering your vehicle to avoid what is in the road. When your tires are in full lock, you cannot steer, your car simply plows forward.

To prevent this very issue, vehicles today are equipped with an ABS. Since the 1970s, with Ford and Chrysler leading the way, car manufacturers have begun including ABS on all their vehicles.

This system uses a number of sensors to detect the motion of your wheels. When brake pressure is applied, sensors determine the exact moment that the wheel/tire is near lock-up. Before it locks up, the sensor transmits a signal to your ABS module, or controller, which then sends a signal to your ABS modulator, or individual ABS valves to systematically pump and regulate your brake pressure, meaning that even the harder you push, you cannot lock up the brakes. The timing of ABS brakes is carefully calculated to provide you with maximum stopping power while still preventing your tires from locking up completely. By doing this, you can apply maximum brake pressure and still steer at the same time.

When your ABS is activated , you’ll feel a vibration as you step down on your brakes. Some vehicles have an ABS light that illuminates to let you know the system is activated. Even if you hold down on the brake pedal, you’ll experience your brakes pulsing as your vehicle comes to a stop. Folks driving in winter conditions usually become far more acquainted to the ABS working, as during snow and ice it becomes very easy to trigger the ABS even with casual braking. Remember that while this may appear annoying, it is far, far better in a panic situation, because this still allows you to steer and avoid something in the road. You may not stop as quickly as if you’d locked out your brakes, but you’re also less likely to slide out of control. If your car lost traction, it could slide, and likely wouldn’t stop until it hit something.

ABS and Stability Control

The same sensors used to determine when to use your ABS are also used in many vehicles stability and traction control. Since 2012, vehicles are required to come equipped with traction and stability control. These innovative features are designed to keep your wheels on the road and avoid tipping when navigating sharp curves and other dangerous features. They work by precisely applying brake pressure to certain corners of the car and can help counter a dangerous spin-out.

Benefits of ABS

Anti-lock braking offers you a number of advantages, although the system is far from perfect. When equipped in a vehicle, an ABS reduces the chances of the following situations:

  • Being involved in a fatal crash
  • Sliding off the road
  • Frontal collision

In many of these instances, drivers attempted to lock out their brakes. Doing so would have caused their vehicle to slide out of control and potentially experience a life-threatening collision.

Potential Disadvantages of ABS

While ABS technology has come a long way since the early systems of the 70’s and 80’s, the system still has some disadvantages. For instance, ABS can in some cases increase the stopping distance of your vehicle. It decreases the risk of skidding, but it could cause a collision when you would otherwise have time to come to a complete stop.

An ABS system adds a myriad of parts that can also fail. These parts, especially the ABS modulator, can be costly to repair.

An ABS system can be rather annoying on gravel, icy or snowy roads as many times even light braking can trigger the ABS. While this can hinder stopping in a straight line, remember the physics discussed earlier of attempting to steer and brake at the same time – you cannot accomplish this well without ABS and therefore can be quite valuable in winter or icy driving.

Understanding Your ABS Warning Light

Most vehicles are equipped with an ABS warning light on their gauge cluster. This light is linked to a series of sensors that monitors your system and warns you of any performance issues. This light may mean that your system isn’t working properly.

When you see this yellow, orange or yellow ABS warning light, something in the braking system is suspect. This system, as well as your stability control and traction control, aren’t working properly anymore and in most cases, all of these systems will be disabled when the ABS light is on.

If you see a red brake light, however, do not confuse this with your ABS light. This could be something as simple as the emergency brake activated, low brake fluid, or a pad-wear sensor. Some vehicles do also have a red ABS light, or blinking light, so it’s good to read your owners manual and get familiar with each light and exactly what it means.

Common Repairs

Luckily, there is one very simple common fix for an ABS light, and that is your brake lights themselves. Many vehicles are wired so that a brake light bulb, even the high-mount brake light bulbs, are wired to trigger the ABS light if one of them is out. This is the quickest option to check. If all brake lights check out, the car will need to be further examined to determine the cause. Many code scanners have the ability to read ABS lights, which can be done at home to help pinpoint what’s wrong. If you do not have a scanner capable of checking ABS codes, you can also check our local preferred shops in your area, who can help assist with any brake issues. Remember, that operating your vehicle without an ABS could put you at risk of losing control of your vehicle in a panic situation, so it’s best to tend to the problem. Aside from the common brake light bulb, these main components of the ABS system can also cause problems:

  • ABS modulating unit – (this unit is under the hood, where the brake lines feed into it. It controls the function of regulating the pressure to the brakes). Some vehicles are also equipped with ABS valves that do this same purpose, one for each wheel of the car, rather than an all-in-one unit.
  • Wheel-speed sensors – these sensors are a magnetic pickup that reacts to a cog wheel, either located on the brake rotor or axle/CV axle. While they can fail, they can also become clogged with brake dust, rotor dust, or road grime and sometimes need to be cleaned.
  • ABS Control Module – This unit is a micro-processor, similar to a vehicle’s ECU that receives and directs the signals from the wheel speed sensors. Sometimes, this is located within the Body Control Module, the ECU itself, or is a separate unit.
  • Wiring between controller and sensors
  • ABS fuse

Whether you’re confident in a DIY electrical repair project or would prefer to take it to a reliable mechanic, it’s important to fix the issue. Some issues, like damaged wiring or brake pad and rotor replacement, are quick and inexpensive. Others, like a new ABS modulator, can be very expensive just for the part. Either way, prompt repair work can restore power to your ABS and keep your vehicle safe from collision and skidding.

These components can be either damaged, clogged, or loose. As mentioned before, ABS sensors can easily be covered in dirt and other grime, which prevents them from working effectively. The normal jostling of your vehicle could loosen wiring connectors, causing them to unplug from your controller or sensors. These issues don’t require any new parts purchases, but will need to be solved before your ABS is operational.

Keep Your Vehicle Braking Safely

While you’re checking out your anti-lock braking system, it’s a good idea to inspect your brake system. Worn-out brake pads, sticking calipers or low brake fluid could all prevent your vehicle from braking effectively when you need it most.

Now that you know what does ABS mean in a car, it’s time to solve your ABS warning light issue. Check out these common repairs or stop by your a mechanic to have an inspection.

Advice, how-to guides, and car care information featured on and AutoZone Advice & How-To’s are presented as helpful resources for general maintenance and automotive repairs from a general perspective only and should be used at your own risk. Information is accurate and true to the best of AutoZone’s knowledge, however, there may be omissions, errors or mistakes.

Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.

FREE Loan-A-Tool® program requires returnable deposit. Please note that the tool that you receive after placing an online order may be in a used but operable condition due to the nature of the Loan-A-Tool® program.

Related Posts