The PCM does control the trans shift points, so that problem also points back to the PCM.
The new PCM may very well cure the problem, but then again, it could be something else. If it were mine, I think I would pay the dealership the charges to scan the PCM, it may only need an upgraded flash to get everything back to normal. Once you buy a new PCM, no returns on electronics......so if it isn't the PCM, you're gonna be out the $800.
If your mech has the same diagnostic tools as the dealer has (somewhat doubtful in my mind) and has failed to reflash, then the dealer would most likely run into the same problem and you would still need the new PCM.
Choices, choices.... isn't life challenging!
