As it turns out, the loose ground wire was in fact the issue causing my power steering to cut out randomly. After the dealer (supposedly) followed the loose ground wire service bulletin my car continued to have the problem so I took it back to the dealer. Because the issue was not resolved, the GM technical advisor recommended a replacement of the power steering gear, electric motor, and control module. Even after those were replaced my problem persisted. Because the dealer seemed unable to resolve the issue I took it upon myself to look into the problem. Through a family member that is a GM engineer, I got the original service bulletin for the loose ground wire and followed the instructions. That particular bulletin did not correctly identify the engine ground location so I looked around the engine block until I found the bolt that held down the ground wire on the front driver side of the engine block. Sure enough the bolt was barely finger tight and once I torqued it to spec my problems have not come back. I've attached a photo to show what the bolt looked like.
