2003 Chevy Silverado 2500HD/4L60E Automatic Transmission

After replacing a cracked flywheel, the truck will shift into gear but the transmission won't engage. We have checked the torque converter allignment, all electrical shift controls and everything looks good.

Does anyone have any idea what could cause this problem? Everything was running fine prior to replacing the flywheel, so it's pretty clear it's something we did.

Any help is greatly appreciated! Thank you!!

 

Did you unhook battery, when you took wiring loose. Might need too clear codes if you did not.