Dumb quwstion

[t8ter]

I was driving in last night when I noticed something strange.I was hauling some jugs of diesel in my bed.I tapped my brake, to light up the bed.Checking to see if any jugs had fell over.When I tapped the brake the truck geared down.Tapped it again and it geared up.Then I tried it going down a hill.It was like the truck dropped into neutral.Are these truck susposed to do this?By the way my truck has a rebuilt tranny with a h/d tc.And it shifts like crap.Way to hard for me.

[TurboSevenThree]

Yes. It actually shuts off the injectors (or some of them) I believe (if it's an auto)I'm not sure HOW it does it, I'm anxious to know. If you hit the brake and let go you're coasting then if you slow down more it will drop back to idle eventually. It does it on it's own if it coasts far enough, around 1000rpms it'll drop to 680-650(idle speed). If you are going fast (55 or over ... ish) and break hard it'll kinda go like "brup... brupbrup...brup... brumbrumbrumrbrum" back to idle. OR if you slow down fast and then get on it a lil again (say someone decides to STOP and then you go around them) it'll have shifted down so it sounds kinda like "woooOOOOOOOMM" like it neeeeds to shift, and it will when the rpms kick up for it.
It's part of the engine braking. I love it, I think it's awesome.