Trying to help a buddy of mine out with a ls swap into his 89 chevy truck. 2002 engine and trans (4L60e) and 0411 PCM. Someone else tuned it for him and he's been driving it for a few weeks now, but the trans starts in 2nd gear in low 1 and D, and you have to manually shift it to get it in 4th. No first or third. You cannot get 1st or 3rd gear no matter where you move the shifter. It doesn't "appear" to be in limp mode. The trans was working fine in the donor tahoe. But this is a different PCM.
Aside from checking for 12v+ at the required locations,and checking the wiring on the harness, what are some things in the tune I can look for verify are correct for proper operation, such as VSS setting and such? What is the PCM looking for from the trans for it to properly control it?