After you pay to have it done and it does not fix the problem. Best advice is probably to let a GM shop diagnose & repair. They usually charge 1 hour labor for TechII work.

You might want to find out what the stealer will charge for the part. Then find out their labor charge. See if you save anything. You can get the GM price (what your stealer will charge) from gmpartsdirect.com or any of the other online gm parts places, as well as your "online" price.