I think I have the answer to many of your problems. I have learned by researching that the BCM module on the Monte Carlos is causing many electrical problems to alternate on and off. The BCM module is a computer controlled cluster that controls everything from temperature gauges, to windshield wipers, to the fan, to the security system... many things. The unit tends to vibrate itself apart causing many things to go on and off or rather work sometimes and not work other times. Just letting you know! Fixed mine and things are great again!

 

did they fix it or replace it?