[HUMTECH]

What sometimes happens is when your onstar is not activated it may wake the module up and search for a signal. When the onstar module wakes up it can draw between 250mA to 400mA which at that rate of 400mA would take approx 1 and a half days to drain a battery enough to cause a no start. Also there is typically around 35 to 50 mA draw from all other components which could take your total draw to 450mA. Now add in a remote start or other aftermarket devices and you may get up over 500mA or more. That can drain a battery overnight.