Ever sense the automatic trans. has been made there has been a mechanism incorporated into them that allowed the driver to down shift the trans from out of a higher gear into a lower gear with the use of a cable or switch so the driver wouldn't have to take his hands off off the steering wheel every time he needed to do this. most trans. use a cable, but a few use a switch. its called a detent cable or detent solenoid. about the only reason you would need to downshift into a lower gear while driving down the road would be to pass another car on a 2 lane rd (thats all we had in my day). so over the yrs. this cable/sol. came to be called a detent cable/sol.,a kick-down cable/sol., and most of the time in my part of the world it was called a Passing gear cable/sol. some body says there is no such a thing as a passing gear, but I believe there is, and a passing gear cable/ sol. makes it work. thats my story and i'm sticking to it. .