YESTERDAY, I HAD HARDLY ANY BRAKING POWER. THE BRAKE WAS TO THE FLOOR, AND I STILL COUILD NOT STOP THE CAR COMPLETELY. I HAVE NOT NOTICED ANYTHING WRONG WITH THE BRAKES ON THIS CAR. THE CAR KEPT ACCELERATING BY ITSELF. WHEN I TRIED TAKING MY FOOT OFF THE BRAKE, THE SPEEDOMETER KEPT GOING HIGHER AND HIGHER. THE CAR NEEDS A NEW RACK AND PINION, BUT WHAT HAPPENED YESTERDAY WAS SOMETHING OTHER THAN A RACK AND PINION PROBLEM. NO WARNING LIGHTS CAME ON. THE CAR FELT OUT OF CONTROL, AND IT WAS ALMOST IMPOSSIBLE TO TRY AND STOP / PARK IT. WHEN I DID PARK IT, THE CAR JOLTED/ ROCKED. I SMELT SMOKE / BURNING COMING FROM THE HOOD. COULD A DEFECTIVE VACUUM LINE BE THE CAUSE OF SOME OF THIS? THIS IS A 1999 GRAND AM. THANK YOU.

Did they no what they were doing,? Replace the master cylinder for the brakes, End check the lines going to the Brake perporshener that they are not leaking,

First, check your brake fluid levels, if it is low then that enplanes your problem. Also, when was the last time you had the brakes changed? if the are worn down, then this will also cause a low fluid level. if the brakes are fine and the fluid level is good and you still have the same issue, then your problem is probably your master cylinder. Brake boosters hardly ever go bad.

You have a failed brake master cylinder, you need to have it replaced and then the system bled of air. This requires special tools for the ABS brake system hydraulic control module.

A bad wheel bearing can make the abs light come on.

Well this is very serious I hope you deal with it right away. You mentioned that sometimes the pedal was hard,do you mean that its all the way up and it doesnt feel like you have power brakes?? If so have you noticed any sounds like air escaping (swoosh sound when brakes applied)? Failure of the power booster causes pedal to become very hard and could possibly be your problem for hard pedal if I understood you correctly. check to make sure that vacuum to the booster is conected properly and hose not kinked..Now for the solution for the pedal fading to the floor... You either have air in your brake system, A bypassing master cylinder , or a hydraulic leak...Were your brakes serviced recently?? if so try bleeding your brake system first...That would be the first step if still the problem persist I would isolate exactly where the problem was coming from.. To do this you would start at the passenger rear wheel and line clamp the brake hose to make that part of your brake sytem inoperable...when clamped try your brakes and note if brakes improved or had know affect on system (when testing obviously im not suggesting you drive to determine results of test procedure)repeat test for each wheel you have isolated the problem when brakes feel normal with one wheel clamped,which ever it may be.. This isnt as hard as it might soun and if you are confused at all dont hesitate to ask questions... Remember the only dumb question is the one you fail to ask I would hate for you to get into an accident ... Good luck!!!

Do you still have the problem ? If so, try disabling the ABS completely (electrically) by disconnecting the 50 amp breaker and remove the ABS controller. You should have brake power restored and be careful as the brakes will lock now if you apply too much foot pedal pressure. I hope this helps.

i really know anything about a powerbooster