Most passenger vehicles are coming out with ABS, otherwise known as Antilock brakes. Let's take a look at their design and function. ABS uses wheel speed sensors, a hydraulic control unit, and a computerized electronic control module, which is the "brain" of the system. When the brake pedal is applied, the electronic control module monitors the speed of the wheels through the wheel speed sensors. If the control module detects that one or more wheels are about to lock up, the module signals the hydraulic unit to control hydraulic pressure to that wheel(s). This varying of pressure is much like "pumping" the brake, only with the ABS system the wheel that is locking up (causing a potential loss of control) is the only one being controlled, the rest of the wheels are free to roll. This maximizes vehicle steer-ability.
Aside from the addition of these components, the braking system pretty much remains the same in design and operation. Replacement of friction materials, such as brake shoes and pads, is the same. As with any new product, "bugs or gremlins" usually show up in the form of little nuisances during the first few years. In the case of ABS brakes, it's the annoying little dash light that comes on and says either "Brake" or "Antilock" or 'ABS". "The brakes work fine but the light is on", you say. Vehicle manufacturers are well aware of this and, as we speak, are working on a solution to this annoying problem. It seems that when moisture and road salt find their way into the wiring harness, either through cracked wire insulation or worn or loose electrical plugs, the light will be tripped because of high resistance sensed by the system. I'm sure they will come up with a way to waterproof the wiring harnesses effectively. In the meantime, all the computer knows is that it senses a problem in the system and must alert the driver via the dash light.
Am I saying to ignore the ASB warning light? Absolutely not! We're talking about you and your family's safety here! Get it checked out! Traveling down a steep grade at 65mph, coming up on the back of a loaded gasoline tanker truck is not the time to find out that your brakes don't work!
Here are a few things you may notice if you've never used antilock brakes:
- When the pedal is applied and ABS is activated, the pedal may feel harder than usual, this is normal.
- The pedal may seem to ratchet or pulsate (vibrate) or there could be a combination of these sensations, this is also normal.
- Finally, you may hear a noise that sounds like a motor boat engine; this is the hydraulic control unit operating, again normal.
Remember two important things when driving a car with ABS brakes:
- Maintain the same safe stopping distance from the vehicle ahead as with conventional brakes. ABS will not make the vehicle "stop on a dime."
- Do not pump the brake. Just apply firm, constant pressure and let ABS do the work for you. You may feel a slight vibration or hear noise as the hydraulic control unit functions. Be ready to push the pedal further if it travels closer to the floor.
Following these tips will help you adjust to using ABS brakes and will increase your confidence and appreciation of them!
'Til next time ... keep rollin'