Hello all from south texas,

i bought a 2004 GM and as soon as i back out or take of straight, i get this little 1 or 2 second brrr noise and vibration in the pedal and on the floor, its driving me nuts trying to figure it out.....some freinds have said it may be the trac control but it does it even if i turn it off, and its every time i turn the car off and start it back up and take off.....its probly just a anti-lock motor or the trac control but i'd like to know for sure cause its fairly noticable any info would be greatly appreciated ya'll oh, its an ls version with all the options