10. Since the 4L80E is an electronically controlled transmission, it needs a controller. HGM Electronics makes the Compushift II automatic transmission control system. It controls when to shift, how hard to shift, when the torque converter should lock up, when the overdrive should engage, and multiple other transmission functions. The beauty of using the Compushift II controller over some factory ECU ripped out of a junkyard is that you have complete control and adjustability via a handheld adjustment display. Multiple modes allow for programming for smooth, soft shifting around town (mode A) and more responsive and firmer shifts in a second mode (mode B).