I had this Jimmy for about 6 months and only in the last couple weeks when it rains the brakes feel like they are skipping on the rotors because the Pedal Pops up when I apply . There pressure feels normal but the pedal pop back up like a pulse only stronger when starting to apply pressure. If I apply hard pressure it seems like it pops back less.

Are you use to an ABS application on a brake pedal? If it only happens when raining, this could be normal......

Only TSB I've seen similar to this, is ABS activating when slowly coming to a stop......this is caused by corrosion build up between the sensor and the knuckle....

It has not happened behavior before raining or otherwise, so I don't beleive it is normal. I have had a simular action feel with traction control on my malibu but not with the brake pedal. This scares the crap out of me when it slips like that and I turn it off.

You comment about the TBS seems quite relevent, can I take a wirebrush and clean up the sensors, or would I have to replace them? I don't have any engine codes.

What the TSB states, is remove the front sensors, clean the mating surface of the knuckle, by removing any rust build up, lightly coat with a rust inhibitor on knuckle surface, clean sensors(just remove dirt or metal shavings) and then reinstall the sensors....

I agree with tech2. Another thing watch for is a loose hub bearing. My wifes blazer would do the same thing only at low speeds. Found a loose hub bearing causing the sensor too drop out at times.

That'* a great tip on checking loose hub bearing.

Pull the ABS fuse and see if the problem goes away. It won't fix the problem but it might tell you whether or not it is ABS related.