I remember an old post that explained the different modes of operation. I went back through all the pages but could not find it. Wondering if someone has a breakdown of what each mode references for its operation. Modes 1-5 to be exact. Mode 5 is Normal Mode. We need this mode means everything is working correctly and the emissions system is not in any other state. This is when the ECM will use your tune file correctly. For example what about Mode 1: Flow control mode? What does this mode relate to and why does the truck use it? Many of us know the basics as in when the truck is regening and so forth but any extra insight to these modes would greatly be appreciated.