I had looked into removing the OnStar unit in my first gen Chevy Volt when I bought it a few years ago. I had found the same information, if I removed it the car would have all kinds of weird behavior.
Unrelated to removing telematics, but I've also had it go completely insane when the 12V battery us even slightly low. Chevy puts their cars into a battery saver mode that disables a bunch of systems, then it throws error messages for all the disabled systems needing service.
Makes me really appreciate my 1980s pickup truck. The last owner had the dealership clean out the gas tank and their mechanic forgot to reattach the fuel pump's ground. It was happy, but even that didn't stop it from running.
Unrelated to removing telematics, but I've also had it go completely insane when the 12V battery us even slightly low. Chevy puts their cars into a battery saver mode that disables a bunch of systems, then it throws error messages for all the disabled systems needing service.
Makes me really appreciate my 1980s pickup truck. The last owner had the dealership clean out the gas tank and their mechanic forgot to reattach the fuel pump's ground. It was happy, but even that didn't stop it from running.