Brakes grabbing when backing up.....

What is your question?

Maybe once or twice a week, according to how much i drive the car, when i put the car in reverse the brakes grab for a minute then release..... when this happens the message board says "traction control active"... then it goes off until it does it again.... no code lights up and it only does every once in a while when i put the car into reverse... going forward everything is normal!!!