Recently my 2002 GT has been shifting pretty hard. I first noticed a few hard shifts when shifting from 2nd to 3rd before christmas. I got the transmission fluid and filter changed last week and the problem seemed to all but go away. Today when I was driving it the shifts from 2nd to 3rd and 3rd to forth were really hard (you could feel the tranny engage gear). The car seemed to only shift into 4th once or twice and didn't seem to shift when i decelerated and returned to about 95km/hr.
From what I have read in other threads there should be a code thrown if the transmission goes to max pressure causing a hard shift. I am thinking of taking it to check for codes and then take it to a local transmission shop to have the pan looked at for shavings and such.
Any suggestions on what could be done to fix this problem? I found a used transmission for 500 from the same year grand prix, but it has about 3000 kms more than mine and could have the same problems. Thanks.