QuestionQUESTION: Hello, I have a 2006 Chevy Malibu and everytime i brake the ABS doesnt engage (no pulsation in brake pedal) In fact, i have tried going 30-40 mph down a straight road and slamming on brakes produces a "fish-tail" brake lock everytime. I just recently had my brakes done in the front, but not the back. Could this be the problem? Any help would be awesome!! thanks
ANSWER: If you are getting lockup of the rear brakes, then the anti-lock is definitely not working. I would go back to the shop that did your brakes and ask them "WTF?" They may have messed with the sensors when they were working on the brakes. When you first turn on the car, the ABS light should come on as the car does a self-diagnostic, and then go out by itself. If you trigger the ABS while driving, the light should come on and stay on until the next time you turn the car off. If the ABS light wasn't coming on at startup before the brake job, then something was already wrong. The ABS module has its own diagnostics and any good shop should be able to run down the problem with a scanner.
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QUESTION: thanks for the reply! How many ABS sensors does my car have? Do I have 2 ABS modules for the front or does every wheel have an ABS sensor? Like I said, I only had my front brakes done, and nothing done to the rear brakes? Could this be the problem? (the rear brakes)
Answer There is a sensor at each wheel, front and rear. The computer that operates the ABS looks at the speed signal from each wheel, and then modulates brake pressure to each wheel to try and keep the speed of each wheel the same. If all wheels are turning at the same speed, then you have complete control through all four wheels. If one wheel locks up, or starts to lock up, the computer releases some of the hydraulic pressure to that wheel, allowing it to return to the same speed as the other wheels. The reason that you feel the pulsing in the pedal is that the initial pressure to the wheels is supplied by your foot pressing on the pedal. The computer modulates that pressure many times each second as it fights lockup. Front wheel drive cars are prone to locking the back wheels anyway, so ABS is an especially good idea for them. Now, the mechanic shouldn't have had to touch any of the anti-lock gear in order to do a brake job. If a sensor was disabled or damaged, it was probably purely by accident. Still, the best way to diagnose this problem would be with a scanner.
