If an individual has his ECM programmed and they have to unhook the batteries to change them out or the alternator or for some other reason, and they were unhooked for an hour. Would that set the ECM back to stock? This is for all 3 diesel trucks.

 

Nope. There is still power being stored just for the backup systems. If you un-plug your computer at home even for weeks, when you turn it back on it's all still magically there. Just like your truck computer. can't explain the technicals of how it does it but it does save the last program.

 

Got nothing to worry about now.