Hey guys I did an LS swap on my 1994 chevy crew cab I got a psi harness for the 4l80 and everything. But now when I drive it. It won't shift by its self I have to shift it. If you put it in a gear it stays in the gear no shifting. It also has no passing gear. I'm just so lost and don't know where to start I've tryed everything. Yes I have power at the trans I've replaced the harness in the trans because if was leaking out the plug. Replaced speed sensors and still no change I just need some kind of help please and thank you