interesting braking problem. Once in a while when I go to brake while driving at low speed, the pedal will go half way down, like it's suppose to, then I feel a release of pressure and it goes to the floor. When it goes to the floor, it doesn't stop the vehicle. I usually fix this issue with pump once the brakes right away, it's back to normal. It's almost like ABS kicked in, but it does it on dry pavement, too kinda feel like the car slip on wet pavement. while this happenes i hear a noise come from where the brake booster/master cyinder area? NO check engine light, ABS light, or VDC/Slip light come on while this happeneds too?

 

Have your brakes checked.

 

Definitely check the fluid level and pad wear. Consider bleeding the system in case there is air in the lines or MC.

What kind of noise do you hear? It's probably the ABS pump.

With the car turned off, what happens when you pump the brake pedal a few times? Does it stay hard or does it sink to the floor too? If it only happens when the car is running, you might have a vacuum leak to the brake booster.

 

^+1 .... sounds like air

 

I agree that it's probably air so don't rush out and buy a master cylinder; but, if it isn't air there is a chance that your master cyl is pooched.

 

Yea I've done that pump the brake pedal it ok hard! When it happened the pedal just sink to the floor! Yea I was thinking too it the ABS pump kick ON I've check the fluid level and pads they all ok normal wear no signs of leaks fluid leak! I'm gonna check or vaccum leaks hopefully that's it

 

I think I might have the same issue, it happens usually when there is a weird dip in the road or something. The sound is unlike any other though, kind of like a pinging metallic sound. Brakes seem to be fine otherwise, and I couldn't replicate it if I tried. Wierd.

 

If it's ABS you should feel it in the pedal as well as hear it.

 

Wait........................................................ .......


What????

 

sorry was at work so i didnt have time to spell check! id check my brake fluid it ok and my brake pads are good. while i was checking the pads i seen no leaks what so ever, so i check for vaccum leaks nothing. But i notice where the master cyinder and brake booster bolt the Black paint front the booster looks blubbly like if kinda like if you spray paint striper. but this is only around the the brake cyinder? and the pedal is hard!

 

Brake fluid eats paint so there is likely a leak right where the paint is messed up.
Or, someone spilled some brake fluid onto the booster during a top up.

 

^interesting. didn't know that could cause the booster to fail.

 

I'm not sure when I said that a brake fluid leak caused his booster to fail. I don't think anyone has figured out if his booster is even the problem. But, if the paint is damaged at the base of the master cyl, there is probably a leak there.

 

sorry for the confusion i just assumed the possible overflow of brake fluid might have erroded some of the paint causing a leak which in turn MIGHT have resulted in a brake booster malfunction. but hopefully OP can properly diagnose it and find the source to this problem.