RepairPal Certified shops can diagnose and repair your 2000 GMC Yukon. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
Check your Brake switch, make SURE that it is working by having someone look at your Brake Lights while you press on the Brake pedal. that is the first step I always take when I take when I deal with a shift lock issue.