Brakes issue

[jjcsnlynn]

My 04 has a brake issue that I don't know how to diagnose. The brakes work fine, but if I press on the pedal quicker than normal, it feels like the ABS is kicking in for split second. Once I needed to use the ABS and it worked fine and felt the same as they do when I hit them quickly.

If really feels like it's one ABS cycle before the pedal feels normal. Last year I drained, purges and replaced the power steering fluid and it seemed to happen shortly after that. Not sure it is related.

[DmaxMaverick]

Did the brake system seem affected by the "activation", other than the feel the system becoming active?

It is normal in some circumstances for the ABS system to enter a ready state when rapid and/or hard pedal pressure is applied. It should not, however, interfere with braking friction unless there is a real condition of traction loss detection.

[jjcsnlynn]

No, braking did not seem to be affected. The thing is, I didn't really push that hard. I pushed with the same pressure and speed that I push on my VW Passat. I don't recall the brakes being like that before I flushed the power steering. When I flushed it, I ran the engine and circulated it until the fluid was clear. I wonder if I did something to the master cylinder or the booser.

[DmaxMaverick]

Flushing the power steering system properly should not have any affect on braking, as they don't share fluid, only a mechanical connection from the HB output to the MC input. It is possible that air in the system may have caused a valve to hammer, which can cause the "panic" brake condition perceived by the ABS control. This would be temporary, and shouldn't repeat once the air is bled. The system is self-bleeding.

[More Power]

I was talking to forum moderator Robyn recently, and heard about an intermittent ABS problem that was eventually traced to a failing front unit wheel bearing assembly. Seems the wheel sensor had a problem sensing the notches when just slightly out of alignment (like in a hard braking situation).

So, jack up each front wheel and get a sense of wheel bearing condition...

Jim