Trying to troubleshoot why a GMPP LS3 and T42 cannot communicate properly to make the trans shift. I cannot read the trans cal from OB2 port. Assume I'll need to use the cord and GM software to make updates.
What should I be checking? Assume the MPH and RPM are going into the ECM.
Here is a download I found about it.
https://www.chevrolet.com/content/da...r-10302410.pdf