Cant perform case learn WHY????

[3800cavalier]

Ok, Im trying to do a case learn on my 99 gtp with an hp tunner vcm. It says began than rev the car to limiter. I do and nothing happens. So i tryed it on a 2004 gt2 and it works fine. So than i try a 2003 silverado and it works. So i try it on another 99 gtp and it works. So now im pissed and i take it to the gm dealer and get them to do a case learn on their tac 2. The tac 2 says it cant perform acase learn because the car is not in P or N. So they check the range switch andc it says its in p or n. So im stumped WTF. Someone help please.

[FreemenGMTech]

Originally Posted by 3800cavalier

Ok, Im trying to do a case learn on my 99 gtp with an hp tunner vcm. It says began than rev the car to limiter. I do and nothing happens. So i tryed it on a 2004 gt2 and it works fine. So than i try a 2003 silverado and it works. So i try it on another 99 gtp and it works. So now im pissed and i take it to the gm dealer and get them to do a case learn on their tac 2. The tac 2 says it cant perform acase learn because the car is not in P or N. So they check the range switch andc it says its in p or n. So im stumped WTF. Someone help please.

[sighs]
sounds like to me the shift position sensor information is not being learned/told to the scanner by your high buck ecm. you do know that the ecm also holds your trans controller. is it programed to accept your transmission information.

some transmissions in that year had external shift position sensors... others had internal ones, each would be using a different calibration of the transmission software to "see" what PRNDL is.

were you very specific with the supplier as to what you had?