Braking action involves perception time and reaction time.

First, you have to decide to push on the brake pedal. That is perception time. Then you have to bring up your foot and do it. That is reaction time.

Average reaction time is about 3/4 of a second. But that is only an average. It might be less with one driver and as long as two or three seconds or more with another. Age, physical condition, alertness, coordination and eyesight all play a part. So do alcohol, drugs and frustration. But even in 3/4 of a second, a vehicle moving at 60 mph (100 km/h) travels 66 feet (20 m). That could be a lot of distance in an emergency, so keeping enough space between your vehicle and others is important.

And, of course, actual stopping distances vary greatly with the surface of the road (whether it is pavement or gravel); the condition of the road (wet, dry, icy); tire tread; the condition of your brakes; the weight of the vehicle and the amount of brake force applied.

Avoid needless heavy braking. Some people drive in spurts -- heavy acceleration followed by heavy braking -- rather than keeping pace with traffic. This is a mistake. Your brakes may not have time to cool between hard stops. Your brakes will wear out much faster if you do a lot of heavy braking. If you keep pace with the traffic and allow realistic following distances, you will eliminate a lot of unnecessary braking. That means better braking and longer brake life.

If your engine ever stops while you are driving, brake normally but do not pump your brakes. If you do, the pedal may get harder to push down. If your engine stops, you will still have some power brake assist. But you will use it when you brake. Once the power assist is used up, it may take longer to stop and the brake pedal will be harder to push.

Your vehicle has anti-lock brakes. ABS is an advanced electronic braking system that will help prevent a braking skid.

When you start your engine and begin to drive away, your anti-lock brake system will check itself. You may hear a momentary motor or clicking noise while this test is going on. This is normal.

If there is a problem with the anti-lock brake system, this warning light will stay on. See Antilock Brake System (ABS) Warning Light .

Along with ABS, your vehicle has a Dynamic Rear Proportioning (DRP) system. If there is a DRP problem, both the brake and ABS warning lights will come on accompanied by a 10-second chime. The lights and chime will come on each time the ignition is turned on until the problem is repaired. See your dealer for service.

Let us say the road is wet and you are driving safely. Suddenly, an animal jumps out in front of you. You slam on the brakes and continue braking. Here's what happens with ABS:

A computer senses that wheels are slowing down. If one of the wheels is about to stop rolling, the computer will separately work the brakes at each front wheel and at both rear wheels.

The anti-lock system can change the brake pressure faster than any driver could. The computer is programmed to make the most of available tire and road conditions. This can help you steer around the obstacle while braking hard.

As you brake, your computer keeps receiving updates on wheel speed and controls braking pressure accordingly.

Remember: Anti-lock does not change the time you need to get your foot up to the brake pedal or always decrease stopping distance. If you get too close to the vehicle in front of you, you will not have time to apply your brakes if that vehicle suddenly slows or stops. Always leave enough room up ahead to stop, even though you have anti-lock brakes.

Using Anti-Lock

Do not pump the brakes. Just hold the brake pedal down firmly and let anti-lock work for you. You may feel the brakes vibrate, or you may notice some noise, but this is normal.

With anti-lock, you can steer and brake at the same time. In many emergencies, steering can help you more than even the very best braking.

If your vehicle has vacuum assist power brakes, it is also equipped with a supplemental brake assist system that supplies additional vacuum to the vacuum brake booster if engine vacuum is reduced. Under certain conditions, the supplemental brake assist system may run briefly after starting your vehicle or when you apply and release the brake pedal and it may continue to run even after you have removed your foot from the brake pedal. When the supplemental brake assist system is operating, you may hear a motor running or feel a slight vibration in the steering wheel or brake pedal. This indicates that the supplemental brake assist system is working to supply additional vacuum for your vacuum assist power brakes. This is a normal operation of your brake system and does not require that the brake system be serviced.

Each time you start your vehicle and accelerate to 10 mph, the supplemental brake assist system will perform a self-diagnostic check of the system and you may hear or feel the supplemental brake assist motor run briefly. While you are driving your vehicle, the supplemental brake assist system monitors itself to ensure that it is operating properly. If there is a problem with the supplemental brake assist system, the SERVICE BRAKE BOOSTER message will be displayed on the Driver Information Center. See DIC Warnings and Messages .

If your supplemental brake assist system runs every time you apply and release the brake pedal or you notice that the brake pedal has suddenly become much harder to push and the vehicle takes longer to stop, you should have your vehicle serviced as soon as possible.