trying to get the plug into the TCM on the transmission, pin #2 (ground) broke. Anyone have recommendations to fix it rather than buying a new one? ^^^Top left pin

 

is it broken off flush? Maybe drill it out and secure with a conductive epoxy. Seems to me I have heard of a "silver epoxy" maybe from Radio Shack??

 

Unfortunately it is completely broken off. From the electrically diagram, PIN number 2 is ground (LMM or LGH any idea what that means?

 

try to solder it back on.

 

LMM is a 2008-2010, and the LGH is a 2011-2016 Duramax Diesel engines.
L20 and L96 are 4.8 and 6.0 gasoline engines.
Seems like your vehicle doesn't even use that Pin 2. Easiest way to verify is to look on the vehicle side of the connector to see if there's a wire coming in.