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Understanding Your Vehicle’s ABS (Anti-Lock Braking System)


ABS stands for anti-lock braking system, and it’s one of the most important safety components on your vehicle. Almost every modern car or truck built after the mid ’90s came with this feature as standard equipment, and it’s easy to see why. By limiting the chances that one of your automobile’s wheels could lock up under heavy braking, it makes it much easier to keep control in an emergency situation, especially on wet or slippery roads.

Let’s consider the components anti-lock brakes require to get the job done.

Wheel Speed Sensors

The most important part of an ABS design is the wheel speed sensor, which monitors and feeds the rate of travel of each of your car’s four wheels to the central computer system that controls the anti-lock braking function. By keeping an eye on wheel speed, you can determine which wheels are on the verge of locking up, and which ones can have more braking force applied to them without having to worry about skidding.

Pump and Valves

To selectively distribute braking force to each wheel, integrating a valve into the ABS system’s individual brake lines is required. The valves open and close to send pressure to the brake itself. That pressure is generated by the brake pump, which keeps the brake fluid in the system pressurized after an open valve has released pressure from one or more brakes.

Computer Controller

For your vehicle’s ABS to process all of this information — wheel speed, brake pressure, valve control — software runs in the brain of a central controller to constantly monitor the status of the braking system and keep everything primed and ready for instant intervention. It’s the controller that intervenes just before a wheel locks up to call on the valve to release pressure from the brake caliper, and it’s that same computer that analyzes how quickly a wheel is reducing speed to determine whether it’s at risk of locking or if more pressure can be applied.

You can actually observe the controller in action during hard braking by way of a pulsating sensation in the brake pedal itself. What you are feeling through your foot are the brake valves cycling open and closed in order to avoid lockup, which can occur many, many times per second. With ABS in action, there’s no need to pump the brakes yourself like on older automotive designs, as the controller takes care of that for you much more effectively.

Check out all the brake system products available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on ABS, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Morguefile.

Benjamin Hunting View All

Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States. Over ten years of racing, restoring, and obsessing over automobiles lead me to balance science writing and automotive journalism full time.  I currently contribute as an editor to several online and print automotive publications, and I also write and consult for the pharmaceutical and medical device industry.

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