Special to Car Care Council Spring/Summer 1999 Supplement
Knowing Your ABS Braking System Helps During Unplanned Stops
Today's drivers are fortunate that advances in technology have increased development of automotive safety features. ABS, or anti-lock braking systems, is among the most popular and effective safety features today. In fact, ABS is the second most popular safety feature car buyers seek, second only to safety belts, according to a nationwide survey conducted by the ABS Education Alliance.
While more and more drivers are becoming aware that braking with ABS is different from braking with conventional brakes, many drivers do not realize that there are two kinds of ABS.
Also, some drivers mistakenly believe that ABS brakes are in use every time a vehicle is stopped. In planned stopping situations, the vehicle's conventional, or platform, brakes are used - only in unplanned emergency stopping situations are the ABS brakes used.
It's important that all drivers recognize the features and benefits of each type of brake and practice their use so they will feel comfortable in case of emergency while operating any vehicle.
The following tips from the ABS Education Alliance will help your understanding of your vehicle's ABS:
Know the two types of ABS
There are two types of anti-lock brake systems - four-wheel and rear-wheel. All ABS systems on passenger cars are four-wheel ABS. Some sport utility vehicles (SUV), vans, and light trucks may have four-wheel ABS, but other SUVs, vans, and light trucks are equipped with rear-wheel ABS, also known as RWAL.
To determine whether the vehicle you're driving is equipped with an ABS system, look for a lighted dashboard symbol when you start the vehicle. All ABS-equipped vehicles have an ABS icon, or words indicating an anti-lock braking system, that lights upon ignition. You can also check the vehicle's owner manual to verify which system you own.
Four-wheel ABS
When properly used, four-wheel ABS improves vehicle steerability, stability, and stopping capability in emergency situations. When learning to drive, most drivers were taught to pump the conventional brakes to prevent skidding or sliding in making an emergency or panic stop. During an emergency stop with ABS-equipped cars, four-wheel ABS does the pumping for the driver automatically, at a rate as fast as 18 times per second, whenever a sensor detects the start of lock on one or more of the vehicle's wheels.
To engage four-wheel ABS, place firm and continuous pressure on the brake pedal. Keep the brake pedal down while steering clear of any hazards. Do not take your foot off the brake pedal or pump the brake, as either action will disengage the anti-lock system.
Rear-wheel ABS, or RWAL
Rear-wheel ABS, found on some sport utility vehicles, vans, and light trucks, requires a different braking technique from four-wheel ABS. Rear-wheel ABS is designed to maintain directional stability and prevent the vehicle from skidding sideways in emergencies. Rear-wheel ABS prevents the wheel lock of the vehicle's back wheels only. The vehicle's front wheels can still lock up, as with conventional brakes. Should this happen, ease up on the brake pedal, decreasing pressure just enough to allow the front wheels to roll again, then reapply firm pressure and steer away from any hazards.
Troubleshooting with ABS
Drivers will know that their ABS system is not working if the ABS symbol stays lighted on the dashboard long after the car is started or if it lights while the vehicle is in operation. Your conventional brakes will still work, but the anti-lock sensors will not. If this happens, drivers should follow the traditional lessons they learned for emergency braking or stopping situations with conventional brakes. As soon as possible, be sure to have the vehicle checked by a dealer or qualified mechanic to correct any problem with the anti-lock braking system and reactivate this important safety feature.
In some ABS-equipped vehicles, the driver may hear a mechanical sound, feel vibrations, or find it harder to push the brake pedal when ABS is engaged or "turned on." These sensations are perfectly normal with ABS and are not cause for alarm.
Practice Makes for Effective ABS Use
The ABS Education Alliance recommends that all drivers practice using ABS in an empty parking lot or on a driver education range to become familiar with anti-lock braking and the sounds and sensations which may occur when in use. Additional dos and don'ts for driving with ABS are below. Remember, always "Brake and Steer" to safety.
DO
- DO keep your foot on the brake while making a panic or sudden stop. Maintain firm and continuous pressure on the brake while steering to enable four-wheel ABS to work properly
- DO allow enough distance to stop. Follow three seconds or more behind vehicles when driving in good conditions, more time if conditions are hazardous.
- DO practice driving with ABS in an empty parking lot or other open space. Become accustomed to the noise and/or pulsations that occur in the brake pedal when ABS is activated.
- DO consult the owner's manual for additional driving instructions on anti-lock brake systems.
- DON'T drive an ABS-equipped vehicle more aggressively than vehicles without ABS. Driving around curves faster, changing lanes abruptly or performing other aggressive steering maneuvers is neither appropriate nor safe with any vehicle.
- DON'T pump the brakes when making an emergency stop. ABS pumps the brakes for you automatically, at a much faster rate, and allows better steering control.
- DON'T forget to steer to safety. Four-wheel ABS will not lock up; it enables drivers to steer in emergency braking situations, but the system itself will not steer.
- DON'T be alarmed by mechanical noises and/or slight pedal pulsations while applying the brake in an ABS-equipped vehicle. These conditions are normal and indicate that ABS is working properly.
