Just to clearify here. Onstar DOES have GPS. Onstar was originally Analog, But all Current systems are Digital and older systems in use have been upgraded to digital as analog is no longer supported. (I did several of these upgrades myself).Onstar may very well have memory of your locations as they can track a stolen car.On stars brains are not in the ECM(engine control module)but in the Onstar module itself.I beleive they probably could listen in on an inactive onstar system if they so desired as 911 capability is usually available on inactive cell phones.
OK ,, I can believe most of what you say... my “hands on” OnStar knowledge is a bit old ... I’m quite sure they have converted to CDMA/TDMA or GSM for their cellular service as analog towers no longer give adequate coverage.
If OnStar indeed has GPS why does GM advertise that you get driving directions from a live person... someone on the phone has to tell you when to turn and on what roads ... Do they install GPS positioning (to give the OnStar operator your position) but fail to install a simple 4.3” lcd screen?
You’re right about the brains of OnStar ,, they used to be in the “body” computer (most post 1996/OBD2 cars have 3 computers) .. The engine computer handles the engine and drivetrain ,, the body computer handles the electronic component diag for the body and also the airbags/seatbelt pretensioners and the final computer handles the anti-lock brake system and stability control (if installed).