I am totally stumped and so are the dealers.
My wife was driving to work one day last month and lost all her lights, then the car just stopped. I had i towed home and thought perhaps a new battery would fix it. My son in law discovered the starter was gone so I picked up a re-man and he installed it--voila! It seemed to fix it...but after it had run for 15 -20 minutes a loud screeching sound began which he eventually traced to the starter. It seems that all by itself the starter would re-engage (or perhaps not disengage) and it pretty well cooked it. We took it back and exchanged it for a new one and thought we had solved the problem but after 20 min or so it began to do it again.
Next we replaced the ignition switch as suggested but that didn't solve it either. We tried an new switch but that didn't change anything either. We have also checked and changed the relay.
We have searched to see if someone had installed a remote starter but there is none. His code reader doesn't show
The GM folks have no idea what the problem is and say they've never heard of such a thing.
Meanwhile the car sits in the driveway... The only other source of power to the starter is the the instrument cluster per the schematic. CAN ANYONE HELP PLEASE!