99 suburban dies when starting

I've got a 99' 2500 suburban (4wd, vortec 454). I got it pre-owned a year ago with 56 K miles. I didn't have any problems until around december. I was heading home from my aunt's christmas party and when I went to start it, the electrical system died as soon as I turned the key to start the engine, (I put the key in and turned it so that the heater, radio, and lights were turned on, and everything was fine, but as soon as I tried to start it everything died. I opened the hood got out and wiggled the cables to the battery and everything came back on and it started. This has gotten progressivly worse, I've tried tightening the T-post on the positive terminal and it seems to work, but w/in a week the problem reccures. I replaced the T post yesterday and took a wire brush to the terminal and wire leads. It is starting normally right now, but I'm not sure if the problem has been solved. Any Advice?

Good job
you solved the problem

Yes... you found a well know GM problem. The sideposts on the battery go bad. I am surprised it didn't break right off when you moved it. You should not have any more problems.

I was having the same problem with my 99 burb. We had just gotten back from dinner and the kids wnated to rent some movies. I went into the garage and the truck wouldn't start. The lights came on and radio. So the following day I clean the 2 cables that come up to the battery post. It worked fine for the day and then again the same problem. I ended up replacing the battery and then the starter myself. The problem still was persistant, I spoke with a friend who restores classic cars, he said to cut away the rubber boot/sheathing around the rings where the cables come together and mount to the battery post. That was it problem solved...after spending around $250 for new battery/starter.