Hello! I'm sorry you are having problems starting your Yukon! Unfortunately, not much to interpret here, since there is no way to know all the details of what is going on with your vehicle. You'll need to find a skilled local technician to help determine what is wrong. Check this link to find someone near you: http://repairpal.com/gmc-within-10-miles-of-piedmont-south-carolina-29673
RepairPal Certified shops can diagnose and repair your 2000 GMC Yukon XL 1500. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.