Most cars have one or two brake warning lights on the dashboard. When you first start your car, all of 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 alerting you of 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 (see below) to indicate one of two things:

  • that your emergency brake is on. Release it to solve the problem.
  • that you have lost brake pressure in half of the brake system (see How a Combination Valve Works for details).

Brake warning light

In the second case, you should slowly and calmly pull over and stop. If the brake system has completely failed, you will have to use the emergency brake for braking. If the light stays on, it means that the pressure on one side of the brake system is lower than on the other.

There are a couple reasons this could happen:

  • There could be a leak in one part of the system, making it impossible to hold pressure
  • The hydraulic fluid could be low
In either case, your braking performance will be impaired and you should have the car repaired before driving it again.

ABS warning light

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 indicates a problem with the antilock braking system. The ABS controller will disable the system and your brakes should function as if you don't have ABS. In this case, you can safely drive the car to a mechanic for service.

Here are several interesting links: