Anti-lock brakes is an option that is added onto the regular brakes. When the light comes on, the computer has detected a problem with a wheel speed sensor or something in the hydraulic unit, so it shuts the system down. You are left with standard brakes just like any other car.
There are a few systems that get their power assist from the anti-lock system pump. If that's the case, you will have to push much harder on the brake pedal to stop.
Since you're not familiar with how these systems work, it should be pointed out that anti-lock brakes are not meant to make the car stop in a shorter distance, even though most Chrysler products do. Their purpose is to prevent loss of steering control. A skidding tire can not be steered.
The light is supposed to come on when you start the engine and stay on for about five seconds while the system performs a self test. If it stays on after you start the engine, suspect a problem with the hydraulic control unit or wheel speed sensors. If the light comes on after driving a few hundred feet to a mile or more, cracked tone rings by the wheels are a common cause. The sensor picks up the crack while monitoring wheel speed. It turns the system off because it knows it can't rely on that cracked ring for an accurate reading.
Cracked tone rings are more common on older cars, and in northern states. Water gets under the ring, freezes and expands cracking it.
Once the light has come on, a diagnostic fault code has been memorized by the computer. Your mechanic will plug in a hand-held computer called a scanner to read the code number or description which will help to lead him to the problem.
Monday, March 30th, 2009 AT 2:05 AM