Need help with weird brake problem
 

I have a 2004 Mazda 3. a few months ago I went over a bump in the road and my brake pedal dropped low. But while i continued to drive home it was restored to normal. I check the fluid and it was fine. It happened again a few weeks later and I went to my mechanic but he did not see anything wrong. then it happened a 3rd time and this time the pedal did not recover. so when I took it to the mechanic he said it was the brake master cylinder. so we changed that. it is about a month later and it has started again. it always happens when I go over a bump and then it recoves to normal. Help! Please!

I assume you need to be pressing the brake when going over the bump for this to happen...?

If you hit a bump with the brakes applied, the ABS will probably activate, and I'd be the ABS pump is not repressurizing the system properly after an ABS event. I am not too familiar with the valving setup, but I know that the system can alter the pedal position a little bit. This car also has brake assist (or at least later models do), though that would actually be applying the brakes, it could be part of the system issue as well.

Good luck, let us know what you find out.

Hey thank you very much. what you suggest makes sense. I will discuss this with my mechanic. will let you know how it goes.

now mid august and I just became a member, from what I read you say you hit a bump and then had the brake problem - I am wondering the condition of the wheel bearing(s), if you have a bearing that is loose striking a bump may cause movement on the rotor causing the piston to be forced inward, this may cause a low pedal. Without having the bump clue I would think the master cylinder was bypassing :)
Scott

Mazda 3 wierd brake problem
 

Thanks a lot for your response. I am still struggling with the problem.. My mechanic is not sure but he is leaning to replacement of the ABS pump. however that is quite expensive. I will give him your take on it.

Hi there!!! I have the same problem!!
 

I have the same problem!!! How did you got it solved? Thank you!!! Jean

hi. I have a 2006 mazda3 and the horn and brake lights stoped working so I went to the garage and they fix then but 10 min. later the brake seize up.they got then working again but after driving a while they started to seize up again so I stopped a while and they on seize.how can I fix this. thanks mike