Has anybody heard a rattling noise coming from under their H2 Hummer? I am trying to find where this noise is coming from. It rattles at low revs especially when the vehicle is first started. The auto trans does not change into 3rd or higher gears. I have to manually change from 1st into 2nd--could this be connected to the rattling noise?. Please respond if you have any suggestions. I am an 80 year old and cannot get under the vehicle to check this problem. Many thanks.