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Welcome to Brain Stuff from howstuffworks.com, where smart happens.

Marshall Brain

Hi, I’m Marshall Brain with today’s question, what do the brake warning lights mean in my car? Most cars have one or two brake warning lights on the dashboard. When you first start the car, all the lights on the dashboard should light up. This is the bulb check. They should go out in a few seconds. If a light doesn’t go out, then your car is trying to tell you that there’s a problem. If a light does not light during the bulb check, it tells you that you need to replace the bulb.

Your car illuminates the brake light to indicate one of two things. Either your emergency brake is on and you release it to solve the problem, or that you’ve lost brake pressure in half of the brake system. The brake system is divided into two parts, each part controlling two wheels. The goal is to lower the risk of a complete brake failure. If one half of the brake system loses pressure, the light comes on. Releasing your emergency brake is easy enough, but what should you do if you’ve lost brake pressure? You should slowly and calmly pull over and stop

If the brake system has completely failed, you’ll have to use the emergency brake for braking. If the light stays on, it means that the pressure on that one side of the brake system is lower than on the other. There are a couple of reasons why this could happen. There could be a leak in one part of the system, making it impossible for one part of the system to hold any pressure. Or the hydraulic fluid could be low, probably because of a leak. In either case, you should have the car repaired before you try driving it again.

Cars with antilock brakes have an amber or yellow warning light which usually says ABS. If this light stays illuminated after the bulb check, it means that there’s a problem with the antilock braking system. The ABS controller, which is a computer, will disable the system and your brakes should function as if you don’t have ABS. In other words, they’ll work fine but you won’t have the anti-skid properties. In this case, you can safely drive the car to a mechanic for service.

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