Vibrations in brake pedal

So lately I have been noticing that occasionally when braking while going down hill I feel some vibrations in the brake pedal, I'm assuming it has something to do with the ABS system but since im am new to ABS I have no idea where to start looking, any suggestions?

Your rotors could be warped or your wheels could be out of balance.find a wet road and jam on the brakes,if you feel the brakes pulsing through the peddle and you come to a halting stop,then your abs is working,in which case you would be looking else where

vibrating brake pedal with no shaking of the steering wheel? Sounds like your rear rotors may be warped.

The discs may or may not be warped, but it's complicated to explain the science behind it. Depending on your comfort level with driving, you can try engaging the parking brake at speed to determine if the judder is coming from the front or rear. The red brake lamp will illuminate, and you will hear a chime while the pedal is depressed. This is normal, and will go off when you release the pedal. Do this on a quiet, straight portion of road at ~ 50 mph - if you feel the pulse, you know it's the rears. If not, you know it's the fronts.

Easiest fix is a brake job, replacing pads/rotors on the offending wheels. There are ways to 'scrub' the rotor clean if the problem is just beginning, but if in an advanced stage the rotors may be warped. Using a dial indicator, you may be able to rotate the rotors for less run-out. It depends on the level of experimenting you are up for.

If this were an ABS issue, your ABS lamp would likely be illuminated.

I really dont think it's a rotor issue, Im well aware of what warped rotors feel like through the pedal and it's not the same thing. I should have done a better job at explaining it but the vibrating is more of a violent fast vibrating, and it only happens a few times a week but lately it seems to have gotten slowly worse. I know that with warped rotors the pulses through the pedal are in direct relation to your speed but the vibrations im feeling is always the same, even when barley rolling its a fast vibrating and if I let off the brake and then re-apply it goes away.

Then you probably have a wheel speed sensor going bad and causing unwanted ABS engagement.

Strange the ABS lamp hasn't come on. I think in time if this gets worse, you'll notice the lamp will come on until you restart the car.

Yeah, if it's totally intermittent, the ABS lamp won't come on.....until it becomes more constant of a problem. You can drive with a scan tool and monitor wheel speed to see which one is dropping, usually to 0 mph, which is why the ABS engages.

Taking a test drive with a scan tool (preferably the GM Tech II) is a great idea, take a driving log and monitor the ABS. I don't remember if CarCode will watch the ABS for logging (it will log any emission sensor, it *should* do brakes too I just don't recall).

Be aware that the ABS will engage every so many stops as part of the system self-test.

My "money" is on a wheel sensor problem although this is not the usual failure pattern.

I think you could use a factory manual.

Albertj

Does the brake pedal kick back at you at any time when you hit the brakes? I know in the winter when I get the ABS going off the brake pedal kicks back and I can hear the abs system working.