Considering your brakes are the most important safety feature on your car, it stands to reason that you might be a bit concerned when a brake warning light shows up on your dashboard. But is there really cause for consternation? Should you pull off to the side of the road and call for help? What does a brake system warning light mean?
A Tale of Two Lights – Or Maybe More
Before delving into what a brake warning light means for you and your car, it is important to clear up what might lead to a bit of confusion. When we talk about a brake warning light, we need to understand that there can be multiple dashboard warning lights that pertain to the brake system. Each light has a different purpose. A different meaning. So, the question is, to which light are we referring?
Back in the day, cars had one brake light. It would signal a driver if there was a problem with the brake system. Over time, brake systems became more complex and required a more sophisticated means of notifying a driver of an issue. Today, there are up to four different kinds of brake lights that can illuminate a dashboard display to tell of trouble with specific parts of the system.
The BRAKE light
The simplest (and oldest) light on your dashboard – the one most people refer to when they mention a brake system warning light – is the BRAKE light. When this light comes on, it means one of two things. Either the hydraulic fluid (brake fluid) in the master cylinder is low, or the parking brake is engaged.
Your brakes are comprised of a network of brake lines, tubes filled with hydraulic oil. At one end of the network is a pump called a master cylinder. When you press on the brake pedal, you actuate the master cylinder and put pressure on the fluid in the brake lines. At the other end of the network of lines (at each corner of your car) are the brake calipers. The calipers are hydraulic clamping mechanisms that force the brake pads against spinning metal discs (the brake rotors), creating friction to slow and stop your car.
If the system springs a leak, the fluid level will drop. A leak can cause your brakes to fail. And that’s bad. So, inserted into the master cylinder is a sensor that triggers the BRAKE light when the level gets low.
On many vehicles, especially older ones, the same BRAKE light also signals a driver that the emergency/parking brake is engaged. That way, the vehicle is not driven with the parking brake on (a potentially damaging or even dangerous situation).
The parking brake light
The parking brake is a device that is incorporated in but separate from, the rest of the brake system. The parking brake (sometimes called an “emergency brake”) is often actuated by a cable rather than with the hydraulics. That way, if the hydraulic system fails (i.e. the pump breaks or a severe leak develops), a backup system is in place.
While the BRAKE light on some vehicles serves two purposes, low fluid and “parking brake is on” duties, on other vehicles the parking brake has its own warning light. Actually, it is more of a reminder light. If this light is on, simply disengage the parking brake. If you cannot disengage it, there might be a mechanical or electrical problem that disallows the brake from releasing.
The ABS warning light
The Anti-Lock Brake System (or ABS) integrates with the rest of the braking system to help you maintain control when you drive on wet, slippery, or uneven surfaces. The ABS prevents your brakes from locking up in the event that your tires lose traction with the ground when you step on the pedal. This comes in extremely handy on snowy surfaces when driving on loose sand or gravel.
The goal of ABS is not so much to help you stop sooner (although that is the case sometimes), but rather to allow you to maintain control of your steering while you brake. By making sure your wheels are still rolling even when your tires are slipping, the ABS ensures that steering is still possible, even if it takes a bit longer to stop. In an urgent situation, control of your steering is important.
To do this, wheel speed sensors detect how fast your wheels are rotating. The information from the sensors is transmitted to a computer, the ABS module, where it is constantly monitored. If one or more of your tires stops spinning or locks up because you hit a slippery patch, the computer detects the lack of rotation. Then the computer engages the ABS actuator (a hydraulic pump that communicates with the ABS module) to prevent the wheel from locking up and skidding. The actuator pump squeezes and releases the brakes in rapid-fire succession, rather than simply grabbing and holding on. This way, the wheel slows down, but the tire does not skid.
The ABS warning light comes on to tell you of a problem specifically with the ABS. If the light is on, you will still have brakes, but not anti-lock brakes.
The brake pad wear indicator light
The youngest member of the brake warning light family is the brake pad wear indicator light. Many late-model vehicles come equipped with this feature. This self-explanatory signal alerts you (if your car is so equipped) that it is time to have your brake pads replaced. Brake pads contain friction material that grabs the rotors when you press on the brake pedal. That friction material wears away in time. Tiny sensors detect when your brake pads are nearing their minimum thickness and trip the dash light to let you know the time for a brake job has come.
If you notice any of these brake system warning lights on your dashboard, make sure to seek service soon. A brake pad wear indicator light and a parking brake most likely are not urgent but should be attended to. A BRAKE light or an ABS warning light, on the other hand, each reveals a potential problem with your brakes and should be taken care of as soon as possible.
Columbia Auto Care & Car Wash | Author: Mike Ales | Copyright December 2019
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