@davesmopar has had a thread going here about repairing one of his vehicle’s ECT. So he knows firsthand of which he speaks. An auto-trans has internal tubes filled w/hydraulic fluid pumped to very high pressures. To effect a gear shift a valve in one of those tubes opens and allows the hydraulic pressure to cause an actuator to move. In an electronically controlled transmission the valve is a simple electro-magnet that moves from closed to open by a magnetic force generated by electrons moving along a coil of wire, termed a solenoid. As I recall @davesmopar wasn’t sure if his trans problem was caused by an internal solenoid or another external part. He was hoping it was the latter, b/c the internal solenoids are very time consuming to access.
By contrast my older Ford truck’s auto transmission, the internal valves are small pistons that move in bores the same diameter as the piston, and a spring holds them in one position unless hydraulic fluid overcomes the force of the spring. There’s dozens of internal tubes that form a sort of hydraulic computer called the “valve body” , and the routing of these internal tubes and the valves is what makes the shifting decisions. For example
DMP may well know the purpose for each of those valve body pathways.