If you are sure that your doors are closed and all the interior light switches are off, then it may that your interior light module is 'sticking' on. You can scan the interior lights by scanning the body control module and seeing what the module is commanding. ( You may need a pretty savy tech to do this ) You can also check that your door switches are really working, meaning they are actually turning off the interior lights with a good scan tool. Also, check your rear tailgate door. Make sure it is really closed. Hope this gets you going in the right direction.