In emergency braking situations -- called “panic stopping” in some parts of the United States -- wheels can come to a complete stop while the vehicle is still moving, especially on wet or otherwise slippery road surfaces. Such skidding markedly reduces driver control. The National Highway Traffic Safety Administration describes anti-lock brakes as “Keep(ing) your wheels from locking up, so your car maintains directional control around hazards if you can’t make a complete stop in time.” A fault with this system, as indicated by the ABS light illuminating, should be addressed immediately.
Harsh braking that involves full application usually leads to skidding, with which most drivers are not trained to cope. The driver of a car that does not have an ABS system has to pump the brakes on and off, rapidly and regularly, to prevent wheel lock-up. It is particularly difficult to concentrate on this in an emergency situation. ABS performs this function automatically through the use of an electronic control unit -- effectively, a dedicated onboard computer -- and motors that alter the pressure of the brake fluid delivered to each wheel, keeping them as fully applied as possible without allowing them to stop rotating.
On vehicles fitted with an anti-lock braking system, the brake warning light is separate from the ABS light. The brake warning light is invariably a red symbol that displays on the dash, and it indicates a problem with the mechanical condition of the system. This light could indicate that pads and/or rotors are worn below a safe level, that brake fluid is low in the reservoir or that air has entered the hydraulic system and it is no longer functioning optimally. While these are not ABS issues, the vehicle should not be driven until they are addressed.
The ABS light will illuminate briefly on most cars when they are first started; this is to assure the driver that the system has been checked and is working properly. When the ABS light remains illuminated it indicates the computer has sensed a fault in the anti-lock braking system, with the ABS control module or one or more of the mechanical components. Although most vehicles can still be driven when the ABS light is illuminated, safe braking in emergency situations is likely to be negatively affected. The issue should be addressed immediately. According to GreatAutoHelp.com, traction control systems are also likely to cease operation when the ABS system is experiencing issues.
A properly programmed scanner must be used to display the fault code or codes. Trained technicians can interpret these codes, specify the problems and fix them. It is not recommended that anyone but the most competent of do-it-yourself mechanics attempt to work on a vehicle’s braking system.
