1998 Grand AM Chatter when braking

[wegri4]

I hear a chatter that sounds like the abs valve is trying to do its thing while braking. The brakes work fine only the noise is a little disconcerining......any Idea's?

[Tech II]

Does this happen EVERYTIME you brake?

Your ABS will activate, even on dry pavement, if you come to a stop and your left wheels are on dry pavement, and the passenger wheels are in dirt.....or if you stop and one side goes through a puddle or something that is wet....

You are not talking about a pulsation which you feel in the steering wheel, but a noise from the ABS system?

Do you know what an ABS stop sounds like? Come to a stop off an off ramp, by letting the left side tires stay on the pavement, and let the right side stop on the grassy edge(do this safely with no one behind you, at about 20-30 mph, hit brakes hard).....this will definitely activate the ABS, and make an ABS sound......

If there are no ABS codes, and the ABS is activating, then the first thing I would do is check the tires and the brakes components......If you have mix and match tires with different design tire treads or size, this can cause an ABS activation.....if you have a tire that is bald, and the others have much more tread, this could cause an activation.......if one side has a pad in front that has much more wear, and does not grab as well as the other side, same thing.....if one rotor is not as smooth as the other side, same problem....If a caliper has been replaced on one side, it could possibly have more or less braking power than the other side.....if a rear wheel cylinder leaks on a set of shoes on one side, once again you will have unequal braking and the ABS will activate.....ANYTHING that can cause unequal braking can cause an activation....

[wegri4]

Thank you Tech II, Yes it happens all the time, during normal braking and no there is no pulsing in the steering wheel. I really don't feel much of anything, just hear the anti lock valve starting to activate. It only goes in short bursts. I pulled the abs fuse and went for a test drive and the noise went away, so I am certain it is the abs valve that I am hearing.

I appreciate all your input and will check the brakes for uneven braking as the tires are all the same and in good shape, the front brakes are fairly new but I have not touched the rear brakes so maybe there may lie the problem.