2003 suburban makes a buz...

Check your transmission fluid, make sure it's at the proper level and that the fluid is bright red and not dark like burgundy. Also make sure the fluid is not foaming up, that could be a sign of the transmission oil filter has fallen or the pump is failing. The other thing to is dirty may be gumming up the pressure line servo. Best thing to do is have the transmission serviced and have them do a pressure line test and if they have to, have them raise the line pressure. That can be done with a tech 2 scanner so call around for a good transmission shop who can do this and not take your wallet for simple things do to keep your transmission from dropping. Good luck and keep me posted, be glad to help.