Thread: 04 Brake Problem

Problem started about 2 mo. ago. When backing out of the driveway brake pedal would go down further than normal. Problem starting occuring more often when driving as well. Had a brake fluid leak in the rear passenger tire so I replaced both rear calipers, turned rotors, and new set of Wagner pads (semi-metallic front, ceramic rear). Had local mechanic do the work but the pedal is still going down occasionally (scares the hell out of me). Mechanic said he bled the lines and thinks it's an eletronic issue. In fact, he didn't want me to drive the car home as he feels it is a safety issue. The car has approx. 117K miles on it and my 18yo son is the primary driver so I don't feel comfortable letting him drive the car until I know the problem is fixed for sure. Another note, when I bought the car I used to be able to push the traction button and the icon would show up but it hasn't displayed in a couple of years. I don't know if this has anything to do with the brake issue. Please help!

Does it make a groaning noise when it happens? Maybe you can feel something like a buzz or vibration in the brake pedal?

Since I bought the car it has always made a groaning/rubbing noise when backing out of the driveway or after the car had been turned off. I just had the worked on last Wednesday so I don't know if it's still there.

Just spoke to the wife and I asked her what exactly happened yesterday. We've been careful with the braking since we got the car back so I asked her to start braking earlier than usual during normal stops. She was coming up to a stop and she started applying the brakes and she felt resistance on the pedal and then all of a sudden the brake pedal went down to the floorboard. Scared the crap out of her!

May very well be an ABS sensor issue. If the TC light doesn't come on, it may be because the ABS is malfunctioning (not sure how the lights work in '04+), as ABS controls TC. Start the car, when you first turn the key to the run position, (when all the lights light up and things start ding-donging and such), and check to make sure that the ABS light comes on momentarily. If you didn't know, to check that the various indicator lights are working is the purpose of them all coming on at startup.

The car may be sensing a skid due to malfunctioning ABS sensors; in an effort to correct it, the computer severely limits your braking power in order to regain traction.

This is how this works to my understanding, there are guys on here who spend more time under their cars than I do, so maybe some of them will chime in.

Thanks for the info. At least I'll have something to tell the mechanic.

I bought the master cylinder ,just in case, but wouldn't the brakes be acting up all the time and not just sporadically?

Didn't have the car that long after I got it back from the mechanic so I can't answer your question about the leak. My wife dropped it off yesterday so he can look at it tomorrow. I just thought of another weird issue. I just bought a new set of tires for the car because two of the previous tires had worn down completely. The previous tires were BF Goodrich Precept that were supposed to be good for 70K but I only got 44k out of two of them. The rear tires were still ok but the front tires were damn near bald. I rotated the tires every 5k miles so I find it weird that not all four wore out evenly.

It's been years since I saw a master cylinder starting to fail like this, but I too think it's the MC. If you pump the brake peddle does it immediately firm back up? It seems that gently pushing down on the peddle allows the fluid to leak by in the MC, and a quick jab at the peddle doesn't, when the MC is pitted inside.

It's not common at all for a master cylinder to do that in a modern vehicle, however, definitely take it into consideration because it would cause your issue. And if you say you never hear "pump/groaning" noise when it happens, the MC is likely leaking.

The pedal definitely firms up after pumping. I'm having the MC changed out right now. Thanks for all the help and advise.

Received the car late Tuesday and drove the car most of the day yesterday. Looks like the problem is fixed. Thanks again for all the help.