2017 buick regal can bus intermittent short to ground.

Been dealing with intermittent no crank no start with multiple U codes on all high side modules for better part of a year.  Finally connected bob to dlc and found pin 6 (can hi) shorted to pin 5 and 4.  I cut network in half by disconnecting x115 engine harness and short went away. Re connected it and short returned then disconnected transmission and short on can hi still present.   The only thing between x115 engine harness and transmission is the power steering control module (PSCM).  The short comes and goes while sitting still and car off without any obvious triggers.  I have done physical inspection and dont see any apparent problems with harness but since pscm is under vehicle mounted to the rack motor it's hard to really get to connectors.  Also, as a side note a couple times can low was shorted.

Should i be leaning toward a faulty pscm since its the only module where short is present?  Thanks for any insight! 

You could try bypassing the can lines around the pscm and see if the issue goes away

Yeah i think i can accomplish that once i figure out the x201 connector (pscm extension 12 pin) by the knee bolster. Appreciate the reply Noah.