What is an Anti-Lock Braking System (ABS)?

What are Anti-Lock Brakes?

Applying a large amount of braking pressure can lead to a lock-up of the brakes, which locks the tires, making the car difficult to control. 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 need 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 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.

What Do Anti-Lock Brakes Do?

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 no matter how hard 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 ABS is activated, you’ll feel a vibration as you step down on the brakes. Some vehicles have an ABS light that lights up when 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 it probably 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 systems. 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.

What are the 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.

What Does the ABS Light Mean?

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.

How to Fix ABS Light Problems

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 these codes, you can also check our local preferred shops in your area, who can help assist with diagnosing any brake issues. Remember, that operating your vehicle that’s not working properly 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 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

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 the controller or sensors. These issues don’t require any new parts purchases, but will need to be solved before the system is operational.

Whether you’re confident in your DIY electrical repair skills 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 keep your vehicle safe from collision and skidding.

Keep Your Vehicle Stopping 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.