issue with brakes

[stevemay09]

I drive a 1998 buick regal gs w/ supercharged 3.8. The issue I am having is with the brake pedal "dropping" about 2 inches when pressed. This activates the brake lights, and I have to pull the pedal back up with my toe. There is an audible click both when it falls and when I pull it back up. I should mention that now I also have to use the shift release button on the console to release the shifter from park. Are these two issues related? Normally you have to step on the brake, and push down the button on the shifter to get out of park. When I push the button I can hear a click down somewhere near the brake pedal. Initially the brakes start to apply at the top of the pedal travel, but it "pops", and drops about 2 inches when I reach a couple of pounds of pressure. It doesn't seem to affect the braking of the car, I still have pretty good brakes. There is an ABS code though, as the ABS light comes on when I do this. I'd like to find out if this is a booster issue, an ABS unit issue, or a master cylinder issue. I don't think it'll pass inspection, and i'd like to get it back on the road. I haven't found anyone yet who recognizes these symptoms, and hope one of you guys will have some advice. Thanks in advance.

 

[SwitchPitch]

Back to the top. I'm interested in a fix for this as well, since it doesn't sound like anything I've ever experienced with a car before.
The problems might be related, but it almost sounds like more than one part is failing.

Have you ever replaced the fluid in the system? Not sure how the anti lock feature controls the brake modulation, but perhaps some old contaminated fluid and rusty parts are having their way with things.
Not sure about the booster, but the pedal falling two inches could be the booster or some sort of anti-lock modulation.

Have you had the code scanned to see what it's trying to tell you?

Paul

 

[stevemay09]

OK, thought I'd post what the actual problem was...the booster actually still worked, but the metal pin that goes through the firewall had become loose and was popping out of the booster. Also, the plastic switch that turns the brake lights on and off had somehow been pushed back out of adjustment, so the lights would stay on. I replaced the booster, and adjusted the switch and all is now good again. I thought I'd mention that when replacing the booster, the manual calls for a "gear tension relief procedure" to be done using a scanning device...I didn't have one handy, and didn't do it. Everything seems to work fine though...I think maybe that's if you separate the ABS and the master cylinder? Any-hoo, all codes are cleared, and it's running smooth and cool again (I also replaced the A/C)...now if I can just get rid of the tick (should have let a pro rebuild the heads)

 

[stevemay09]

Oh yeah, I didn't mention the problem with the shifter. I did rent a scanner, which read a code that said something was up with the shift position sensor. Since I had the console out, I cheated and put a couple of o-rings on the pin that keeps the shifter from coming out of park. The codes have been cleared and have not shown back up, so I don't know if the problem has been resolved somehow or not. I did notice that now since there are no codes, my traction control works once again, yea!