rear doors won't lock

Help Please. 2003 Tahoe fully loaded. Intermittently, (50 to 60% of the time) when I lock the vehicle electrically, using either front door buttons, or key fob, the 2 front doors lock, but both rear passenger and hatch and hatch glass don't lock. Alarm is set, so if you open the doors or glass, it will go off and have to be silenced. Don't know if anyone can help.

I am having the same exact problem in my 04. Did anyone ever respond to this post? Can anyone help?

Hello:
No one ever replied. Guess it's not that common. It was still under warrenty for me, so I guess the dealer was trying to do the job cheap to save GM money or it was just misdiagnosed. Dealer replaced drivers door control panel of switches, then on a second visit said it just needed to be reprogrammed and on a third visit replaced a wire harness in drivers door. Each time it worked when I picked it up, but only for a day or two. Went to a second dealer and he said it was a "body control module". He replaced it to the tune of about 7 or 8 hundred dollars if not for warrenty (didn't cost me a penny) and it has worked PERFECTLY ever since. I think, but am not certain that the module in question is actually located in the rear quarter panel on the passenger side, but PLEASE check on this from a reliable source since my memory is not that great after 2 years since I had the problem.