5r55e trans replacement question

[Johnnyb83]

So I recently have attempted to replace my transmission with what looked like a good one from a junkyard. After installing it throws no codes but will not engage any gear I shift into. Do I need to install it into my computer and if so how. Thanks guys

 

[imp]

So I recently have attempted to replace my transmission with what looked like a good one from a junkyard. After installing it throws no codes but will not engage any gear I shift into. Do I need to install it into my computer and if so how. Thanks guys

In general, PCM cares not at all about the trans itself, just works with it's electronics. For "no gear" position engagement:
Did this condition exist with old transmission?
Did old trans engage any gear?
Was Transmission Range Sensor installed properly, and adjusted?
Check for presence of hydraulic pressure.
Possibly pump problem/install jammed torque converter tight against pump (not engaged, can't turn).