A method to prevent parasitic current drain of a vehicle battery includes shutting off the vehicle ignition to initiate a power down sequence of electronic control units, and detecting an excessive current draw condition from the vehicle battery after the vehicle ignition is shut off for a predetermined period of time. After verifying that an excessive current draw condition exists by analyzing data collected from the vehicle, the method continues with powering up the electronic control units on a vehicle communications network and broadcasting a system state equals run, and broadcasting a system state equals off on the vehicle communications network after the electronic control units have reached steady state operation.