im havin same issue, but if i push the lil button on the the colum by the key. the key moves to lock, but the shift problem would still be there. i reset the pcm (more than once) it will start in 1st gear. mine says a low voltage code was present. i checked all fuses, it has a new ingtion switch, and the neutral safety switch is working, if u dont press on the brake it will not move out of park, so thats workin, ive checked the plug at the trans its tight, checked the pcm plugs they are tight, just hope we can figure this out, please help if u can thanks

 

as far asi know mine doesnt have the button under the column mines a 05 zr2 ill have to take cover off to see if there is one. what are pcm plugs ? i now cant get back into acc either

 

my truck had a old o2 fault code, i replaced the sensor, i havint had the limp home mod come back, yet. pcm plugs is the main plugs on the pcm. still sometimes the key will not rock back to off, so all i do is push in on the lil button and rock the key back at the same time.

 

up date
figured out that the igntion switch i had bought was not a ac delco so it went bad. cause the trans fuse no to be hot, so i jump it with a 12v igntion wire. work but not rite, so i got a ac delco switch now all is good.